Dissertations / Theses on the topic 'Epilepsy and sleep'

Il termine epilessia notturna del lobo frontale (NFLE) descrive un ampio gruppo di epilessie parziali presentanti origine eterogenea. Gli attacchi originano a livello del lobo frontale, solitamente durante la fase 2 del sonno, e sono caratterizzati da complessi cluster ipercinetici stereotipati. Circa il 12% dei soggetti affetti dalla forma autosomica dominante di questa patologia (ADNFLE) presentano mutazioni nei geni codificanti le subunità dei recettori nicotinici neuronali (nAChRs) eteromerici. Oltre a promuovere direttamente l’eccitabilità neuronale in un network neuronale maturo, nAChRs mutanti possono contribuire alla patogenesi di questo disturbo durante lo sviluppo del SNC, influenzando il rimodellamento sinaptico. Un’alterata trasmissione colinergica potrebbe perciò condurre ad uno sbilancio tra input eccitatori ed inibitori a livello della corteccia prefrontale (PFC) facilitando così l’insorgenza di accessi epilettici. Abbiamo preso in considerazione gli effetti di una mutazione della subunità β2 associata a un fenotipo ADNFLE (β2-V287L) in fasi precoci dello sviluppo cerebrale. L’espressione della mutazione durante le prime due settimane di vita postnatale risulta necessaria per l’instaurarsi del fenotipo epilettico. Sfruttando un modello murino condizionale abbiamo analizzato come nAChRs mutanti contribuiscano a alterare il bilancio tra eccitazione ed inibizione nel cervello. Abbiamo dapprima analizzato come la mutazione β2-V287L influenzi lo sviluppo del sistema GABAergico. Registrazioni di patch-clamp evidenziano che la mutazione non influenza lo switch eccitatorio/inibitorio della trasmissione GABAergica (il quale presenta un ruolo chiave nel remodelling sinaptico), né influenza l’espressione dei recettori GABAA. Abbiamo quindi considerato il contributo della mutazione a carico del sistema glutamatergico. I risultati evidenziano che i nAChRs eteromerici iniziano ad esercitare il loro effetto verso la fine della prima settimana di vita postnatale in topo. Non sono state osservate correnti somatiche nicotiniche in questo stadio né in fasi più avanzate in neuroni piramidali: tale dato suggerisce che i nAChRs eteromerici sono siti principalmente a livello presinaptico, dove la loro attivazione promuove il rilascio di neurotrasmettitore. L’analisi dei mutanti mutazione mette in luce una più alta frequenza delle EPSCs sia in condizioni di controllo che in seguito a somministrazione di nicotina, rispetto al gruppo di controllo. L’analisi della distribuzione delle ampiezze delle EPSC mette in luce un incremento delle stesse tra P7-9 e P10-12 più pronunciato nei topi transgenici. Il nostro lavoro ha inoltre messo in luce come anche mutazioni loss-of-function possono condurre ad un fenotipo NFLE: abbiamo considerato l’effetto patogenico di una mutazione a carico della subunità α2 (Ile297Phe) identificato in una coorte di pazienti affetti da ADNFLE e NFLE. nAChRs ipofunzionali potrebbero limitare la capacità degli interneuroni inibitori di contenere la propagazione degli accessi epilettici, favorendo perciò l’insorgenza degli attacchi. Risulta quindi chiaro che mutazioni in geni codificanti per nAChRs eteromerici possono contribuire ad un fenotipo epilettico a diversi livelli, promuovendo l’eccitabilità in una rete neuronale adulta (che è ancora suscettibile al rimodellamento) o influenzando lo sviluppo di una rete neuronale funzionale, o entrambi. L’ADNFLE risulta perciò non classificabile semplicemente come una canalopatia, ma come un disturbo più complesso dello sviluppo. Il nostro obiettivo è comprendere meglio il ruolo dei nAChRs nello sviluppo del SNC ed il loro contributo nella nella epileptogenesi, oltre che il loro ruolo nella corteccia prefrontale matura. Speriamo così di identificare una finestra temporale precoce per approntare una terapia farmacologica che impedisca l’insorgenza della ADNFLE.<br>The nocturnal frontal lobe epilepsy (NFLE) comprises a large group of partial epilepsies with heterogeneous origin. Approximately 12% of the families affected by the autosomal dominant form of NFLE (ADNFLE) carry mutations on genes coding for subunits of the heteromeric neuronal nicotinic receptors (nAChRs). Attacks arise in the frontal lobe, usually during stage 2 of sleep, and are characterized by clusters of complex and stereotyped hyperkinetic seizures.This is consistent with the widespread expression of nAChRs, and particularly α4β2, in the mammalian brain.Besides directly promoting hyperexcitability in mature networks through cell depolarization and/or altered neurotransmitter release, mutant nAChRs could determine the pathogenetic process during early developmental phases, by affecting synaptic remodeling. Cholinergic signaling has been recently found to affect the development of both GABAergic and glutamatergic systems. . Aberrant cholinergic transmission can lead to an unbalance between excitatory and inhibitory transmission in prefrontal cortex (PFC), therefore facilitating the epileptic fits.We investigated the effect of β2-V287L, a mutant nAChR subunit linked to ADNFLE, in early developmental stages, during which its expression is crucial for the epileptic phenotype to manifest. By using a murine strain which conditionally expresses β2-V287L, we analyzed how the mutant nAChR modifies the balance between excitation and inhibition in the adult brain, leading to the formation of a neuronal network susceptible to seizures. We first considered how β2-V287L (a gain-of-function mutation) affects the development of GABAergic system. By patch-clamp recordings, we observed that mutant nAChRs did not interphere with the GABAergic excitatory/inhibitory transition during early developmental stages (which is known to play a role in synaptic remodelling) nor influenced GABAA receptors’ expression.We then considered the contribute of the mutation to the development of glutamatergic signaling. Our findings revealed that heteromeric nAChRs start to exert their effect on glutamatergic transmission at the end of the first postnatal week in mice. No somatic nicotinic currents have been detected at this as well as at later developmental stages in pyramidal neurons, suggesting that heteromeric nAChRs are mainly located at synaptic level where they stimulate neurotransmitter release. Analysis of transgenic mice highlighted an increase in EPSC frequency both in control condition and following nicotine exposure, compared to control littermates. Cumulative distribution of the EPSC amplitudes showed a larger increase in EPSC amplitude between P7-9 and P10-12 in transgenic mice compared to controls.In our work we also showed how loss of function mutations can lead to a NFLE-like phenotype: in particular, we considered the pathogenic effect of an α2 subunit mutation (Ile297Phe) identified in a cohort including ADNFLE and NFLE patients. A hypofunctional nAChR could hinder the ability of inhibitory interneurons to contain seizure propagation, therefore contributing to seizures.It appears clear that mutations in genes coding for heteromeric nAChRs can contribute to an epileptic phenotype at different levels, promoting excitability in adult neuronal networks (which are still susceptible to remodelling), or affecting the development of a functional cortical circuitry, or both. ADNFLE appears therefore not only to be a channelopaty but a more complex developmental disease.Our aim is to shed new light on the nAChR contribution to brain development and its role in the establishment of an epileptic phenotype, besides its direct effect on excitability in mature prefrontal networks. In this way, we should be able to identify a temporal window for early pharmacological treatment during the pathogenetic process in order to prevent the establishment of ADNFLE

Epilepsy is a neurological disorder characterized by recurrent seizures. Sleep problems can cooccur with epilepsy, and adversely affect seizure diagnosis and treatment. In fact, the relationship between sleep and seizures in individuals with epilepsy is a complex one. Seizures disturb sleep and sleep deprivation aggravates seizures. Antiepileptic drugs may also impair sleep quality at the cost of controlling seizures. In general, particular vigilance states may inhibit or facilitate seizure generation, and changes in vigilance state can affect the predictability of seizures. A clear understanding of sleep-seizure interactions will therefore benefit epilepsy care providers and improve quality of life in patients. Notable progress in neuroscience research—and particularly sleep and epilepsy—has been achieved through experimentation on animals. Experimental models of epilepsy provide us with the opportunity to explore or even manipulate the sleep-seizure relationship in order to decipher different aspects of their interactions. Important in this process is the development of techniques for modeling and tracking sleep dynamics using electrophysiological measurements. In this dissertation experimental and computational approaches are proposed for modeling vigilance dynamics and their utility demonstrated in nonepileptic control mice. The general framework of hidden Markov models is used to automatically model and track sleep state and dynamics from electrophysiological as well as novel motion measurements. In addition, a closed-loop sensory stimulation technique is proposed that, in conjunction with this model, provides the means to concurrently track and modulate 3 vigilance dynamics in animals. The feasibility of the proposed techniques for modeling and altering sleep are demonstrated for experimental applications related to epilepsy. Finally, preliminary data from a mouse model of temporal lobe epilepsy are employed to suggest applications of these techniques and directions for future research. The methodologies developed here have clear implications the design of intelligent neuromodulation strategies for clinical epilepsy therapy.

INTRODUCTION: Dopamine is a catecholaminergic neurotransmitter. A variety of sleep disorders implicate a dysfunction in the dopaminergic system, particularly REM Behaviour Disorder (RBD), Restless Leg Syndrome (RLS) and Periodic Limb Movements during Sleep (PLMS). PLMS involve stereotyped, rhythmic extension movements of the big toe and dorsiflexion of the foot during sleep. PLMS is particularly frequent in Restless Legs Syndrome (RLS) and other sleep disorders. Few studies have documented a pathological PLMS index in patients with Epilepsy. AIMS: The aims of this study were to evaluate the possibility of an association between Epilepsy and PLMS and to define the polysomnographic characteristics of PLMS. Given the dopaminergic nature of PLMS, the association between PLMS and Epilepsy might have represented an additional, indirect evidence of the involvement of dopamine in the pathogenesis of Epilepsy. Another aim was to evaluate the influence of some dopamine agonists commonly used in the treatment of PLMS on the PLMS pattern of some of the patients constituting our sample, as well as any impact these might have on epileptiform discharges. MATERIALS AND METHOD: We selected all patients referred to our neurological clinic from 2008 to 2012, who had previously been diagnosed with epilepsy based on the ILAE criteria, who showed no signs of Sleep Apnea, RLS, RBD and other degenerative neurologic conditions and who were not being treated with antidopaminergic and/or antidepressant drugs. All patients underwent nocturnal video-polisomnographic recordings . We selected patients who had a PLM index considered as pathological (PLMI>5). Subsequently, 5 patients were randomly selected among those with Epilepsy who had a PLMS index > 5. All 5 patients underwent other two nocturnal video-polisomnographic recordings (before and after administration of a dopamine agonist drug, Pramipexole 0.18 mg). In both recordings, PLMS and epileptiform discharges were also counted and analysed. RESULTS: Eighty-five patients who had been previously diagnosed with Epilepsy met the inclusion criteria for this study. Of these, 17/85 (20%) patients had a pathological PLM index (> 5). Of the 85 patients in our sample, 12/17 (70.6%), were diagnosed with Temporal Lobe Epilepsy, 2/17 (11.8%) with Frontal Lobe Epilepsy and 3/17 (17.6%) with Juvenile Myoclonic Epilepsy. PLMS registered in all 17 patients exhibited a mean PLMS index of 18.78 corresponding to the presence of a periodic nocturnal myoclonus of medium entity. In 58.8% PLMS appeared to be mainly distributed during the first half of the night and in 66.7% PLMS occurred during N2. The analysis of the 5 patients who underwent two VPSG (before and after administration of a dopamine agonist drug) showed a close to 50% reduction of epileptiform discharges in patients with PLMS and Epilepsy after administration of a dopamine agonist, namely Pramipexole. CONCLUSIONS: The study confirms the presence of PLMS in patients with Epilepsy. In our sample, the frequency of PLMS episodes stood at 23%. These movements mainly occurred during the first half of the night, in connection with the N2 stage, with a severity ranging from mild to moderate. They therefore had characteristics and distributions which made them more similar to the PLMS described during RLS than to those associated to neurodegenerative conditions. In addition, the PLMS in our sample were more frequent in patients with Temporal Lobe Epilepsy. Finally, considering the dopaminergic nature of PLMS, their occurrence in association with Epilepsy may serve to strengthen the role of dopamine in the pathophysiology of this disorder. This could have significant repercussions even in the therapeutic field, opening up new possibilities through the employment of dopamine agonists which may well find use in the treatment of some forms of Epilepsy.

Good quality sleep is essential for mental and physical health. Inadequate sleep impacts memory consolidation, learning and cognition, immune function, autonomic regulation, physical performance, and other vital functions. In many neurological disorders that are associated with sleep problems such as epilepsy and Alzheimer’s disease, changes in brain circuitry affect sleep-wake regulation mechanisms; this is reflected in anomalous sleep-wake architecture and usually accompanied by poor sleep depth. Thus, over many years, many approaches have been tried in humans and animal models with the goal of improving sleep quality. Unfortunately, each of those approaches comes with limitations or side effects. Thus, there is a need for a natural, safe, and low cost approach that overcomes many limitations to improve sleep and eventually the lives of individuals with sleep problems. Environmental temperature is one of the most important factors that affect sleep in humans and other animals. Studies have shown that the part of the brain governing thermoregulation is also involved in sleep-wake regulation. Even a mild change in environmental temperature can produce a significant effect on sleep. Thus, a better understanding of the sleep-thermoregulation interaction could lead to novel ways for treating many sleep disorders. As a first step on the translational pathway, experiments in animal models of disease conditions with disordered sleep are needed for investigating sleep–thermoregulation interactions and for devising and validating related approaches to enhance sleep quality before conducting them on humans. This dissertation explores and assesses the effect of changes in ambient temperature on sleep-wake architecture in control mice and epileptic mice, the latter from a model of temporal lobe epilepsy as an example of a disease model with disordered sleep. Then, based on the results of temperature effects on sleep in control and epileptic mice, different strategies are proposed and tested to modulate sleep through ambient temperature regulation in closed loop to improve sleep depth and regulate the timing of the sleep-wake cycle. The results presented in this dissertation demonstrate the feasibility of sleep enhancement and regulation of its timing and duration through manipulation of ambient temperature using closed-loop control systems. Similar approaches could foreseeably be used as more natural means for enhancing deep sleep in patients with epilepsy, Alzheimer’s, or Parkinson’s disease in which poor sleep is common and associated with adverse outcomes.

Introdução: O Padrão Alternante Cíclico (“CAP”, do inglês - Cyclic Alternating Pattern) é um ritmo fisiológico do sono NREM, que corresponde aos períodos de ativação cíclica expressos por eventos fásicos do sono. O aumento na expressão de taxa do CAP tem sido considerado uma medida de instabilidade e fragmentação do sono. O CAP representa uma condição favorável para a ocorrência de descargas interictais e/ou ictais. A modulação do CAP em pacientes com Epilepsia do Lobo Temporal (ELT) não está bem definida. Objetivos: Analisar a expressão do CAP em pacientes com ELT e comparar com o grupo de controle. Selecionar o grupo de pacientes sem distúrbios do sono que possam influenciar a organização do sono. Métodos: Foi realizado estudo transversal com grupo de controle de comparação. A seleção foi pareada em sexo e idade entre pacientes com ELT e o grupo de controle, obedecendo aos critérios de inclusão e exclusão. Os parâmetros do sono e CAP foram analisados em 13 pacientes com ELT (6 do sexo masculino e 7 do sexo feminino; idade média: 33,8 ± 8,5 anos) e 13 indivíduos sadios (8 do sexo masculino e 5 do sexo feminino; idade média: 26,1 ± 9,2 anos), os quais não apresentaram distúrbios do sono. A comparação dos dois grupos foi realizada através do “teste t” de Student e confirmada pelo “teste U” de Mann-Whitney. Resultados: Os pacientes com ELT apresentaram aumento na taxa de CAP (44,02 ± 5,23 % versus 31,83 ± 3 %; p<0,001) e maior duração do tempo de CAP (133,77 ± 15,56 min. versus 99,38 ± 9,6 min.; p<0,001) em relação aos indivíduos sadios. Não houve diferença na média da duração da fase A (9,27 ± 1,15 seg. versus 8,7 ± 0,61 seg.; p<0,131), e a média da duração da fase B não atingiu diferença significativa (22,92 ± 1,71 seg. versus 21,54 ± 1,78 seg.; p<0,054) entre os dois grupos. A comparação dos parâmetros de sono e de CAP dentro de cada grupo, mostrou não haver diferença entre os gêneros. A análise estatística dos parâmetros do sono em pacientes com ELT evidenciou uma diferença significativa das seguintes variáveis: menor latência ao sono (5,8 ± 2,4 min. versus 14,2 ± 7,6 min.; p=0,002); aumento do número da troca de estágios com média de 91,1 ± 25,7 versus 68,2 ± 12,8; p=0,008; menor duração de estágio IV (30,8 ± 14,8 min. versus 51,4 ± 12,5 min.; p=0,001); maior percentual do estágio III (7,7 ± 2,8% versus 5,7 ± 1,7%; p=0,035); menor percentual do estágio IV (7,9 ± 4% versus 12,9 ± 3,3%; p=0,002) em pacientes com ELT, comparando com o grupo de controle. A análise dos despertares breves demonstrou em pacientes com ELT: maior número de despertares breves em sono (66,5 ± 20 versus 41,8 ± 9; p=0,001); maior número de despertares breves em sono NREM (52,9 ± 19,6 versus 31 ± 9,5; p=0,002); maior duração total de despertares breves em sono (549,1 ± 170,3 seg. versus 357,2 ± 88,5 seg.; p=0,002); maior duração total de despertares breves em sono NREM (436,8 ± 165,7 seg. versus 271,9 ± 95,2 seg.; p=0,006); aumento do índice de despertar breve em sono (10,2 ± 2,9 versus 6,3 ± 1,7; p=0,001); aumento do índice de despertar breve em sono NREM (10,3 ± 3,4 versus 6 ± 2; p=0,001). Não houve diferença significativa de número (13,6 ± 5,6 versus 10,8 ± 3,7; p=0,149), duração total (112,3 ± 48,3 seg. versus 85,3 ± 25,2 seg.; p=0,091) e índice de despertar breve (9,7 ± 3,8 versus 7,4 ± 2,4; p=0,075) em sono REM entre os dois grupos. Todos os pacientes comELT tiveram uma eficiência do sono normal e similar ao grupo de controle (90,4 ± 2,9 % versus 90,6 ± 2,9 %). Conclusões: Os pacientes com ELT apresentam aumento da taxa de CAP e da duração de tempo de CAP em relação ao grupo controle, demonstrando um aumento na instabilidade e fragmentação do sono. O aumento na expressão da taxa de CAP, alterações nos parâmetros de fragmentação e descontinuidade do sono, expressos pelo aumento de número, duração e índice de despertares breves em sono NREM e o número de mudanças de estágios, associados à eficiência normal do sono em nosso grupo de pacientes com ELT, podem sugerir que o CAP tem um papel na modulação do sono. A fragmentação e a instabilidade do sono em pacientes com ELT, provavelmente, ocorrem devido à própria epilepsia e podem refletir a interação do foco epiléptico com os sistemas responsáveis pela manutenção e estabilidade de sono.<br>Introduction: Cyclic Alternating Pattern (“CAP”) is a NREM sleep physiological rhythm corresponding to periods of cyclical activation expressed by phasic events of sleep. The increase in the CAP rate expression has been considered a measure for sleep instability and fragmentation. CAP offers a favorable condition for interictal and/or ictal discharges. The CAP modulation in patients with Temporal Lobe Epilepsy (TLE) is not well defined. Objectives: Analyze the CAP expression in patients with TLE comparing it with a control group. Select the group of patients without sleep disorders which may interfere with sleep organization. Methods: A transversal study was conducted with a comparing control group. The selection was paired on gender and age between patients with TLE and the control group, in accordance with inclusion and exclusion criteria. The sleep parameters and CAP were analyzed in 13 patients (6 males and 7 females; mean age: 33,8 ± 8,5 years) and 13 healthy individuals (8 males and 5 females; mean age: 26,1 ± 9,2 years) who did not present sleep disorders. The comparison of the two groups was made through Student’s t-test and was confirmed by the Mann-Whitney U test. Results: Patients with TLE showed an increase in the CAP rate (44,02 ± 5,23% versus 31,83 ± 3%; p<0,001) and CAP time was longer (133,77 ± 15,56 min. versus 99,38 ± 9,6 min.; p<0,001) as compared to healthy individuals. There was no difference in the duration average of stage A (9,27 ± 1,15 sec. versus 8,7 ± 0,61 sec.; p<0,131), and the duration average of stage B did not show a significant difference (22,92 ± 1,71 sec. versus 21,54 ± 1,78 sec.; p<0,054) between both groups. The comparison of sleep parameters and CAP within the group showed that there is no difference between the genders. The statistical analysis of sleep parameters in patients with TLE showed a significant difference in the following variables: lower sleep latency (5,8 ± 2,4 min. versus 14,2 ± 7,6 min.; p=0,002); increase in the number of stage shifts with an average of (91,1 ± 25,7 versus 68,2 ± 12,8; p=0,008); lower duration of the stage IV (30,8 ± 14,8 min. versus 51,4 ± 12,5 min.; p=0,001); higher percentage of the stage III (7,7 ± 2,8% versus 5,7 ± 1,7%; p=0,035); lower percentage of the stage IV (7,9 ± 4% versus 12,9 ± 3,3%; p=0,002) in patients with TLE as compared to the control group. The analysis of arousals in patients with TLE showed: a higher number of arousals during sleep (66,5 ± 20 versus 41,8 ± 9; p=0,001); a higher number of arousals during NREM sleep (52,9 ± 19,6 versus 31 ± 9,5; p=0,002); a longer total duration of arousals during sleep (549,1 ± 170,3 sec. versus 357,2 ± 88,5 sec.; p=0,002); a longer total duration of arousals during NREM sleep (436,8 ± 165,7 sec. versus 271,9 ± 95,2 sec.; p=0,006); an increase of arousal index during sleep (10,2 ± 2,9 versus 6,3 ± 1,7; p=0,001); an increase of arousal index during NREM sleep (10,3 ± 3,4 versus 6 ± 2; p=0,001). There was not a significant difference in number (13,6 ± 5,6 versus 10,8 ± 3,7; p=0,149), total duration (112,3 ± 48,3 sec. versus 85,3 ± 25,2 sec.; p=0,091) and arousal index (9,7 ± 3,8 versus 7,4 ± 2,4; p=0,075) during REM sleep between the two groups. All patients with TLE showed a sleep efficiency that is normal and similar to the control group (90,4 ± 2,9% versus 90,6 ± 2,9%).Conclusions: Patients with TLE showed an increase in CAP rate and a longer CAP duration in relation to the control group, demonstrating an increase in the instability and fragmentation of sleep. The increase in the CAP rate expression, alterations in the parameters of sleep fragmentation and discontinuity that as expressed by increase in the number, duration, arousal index during NREM sleep and number of stage shifts, associated with normal sleep efficiency in our group of patients with TLE may suggest that CAP may have influence in the modulation of sleep. Sleep fragmentation and instability in patients with TLE may occur probably due to epilepsy itself, reflecting the interaction of the epileptic foci with the systems responsible for the maintenance and stability of sleep.

Substance abuse and mental health disorders are a leading source of years lost to disability from medical causes worldwide. Unfortunately, for most neurological disorders it is unclear how underlying genetic predispositions govern behavioral response to environmental stressors. Owing to their convenience, genetic tractability, and small brains, the fruit fly, Drosophila melanogaster, has become an invaluable model in which to dissect the neurological basis of conserved complex behaviors. Here, I characterized the respective roles of two genes in alcohol response and sleep behavior. Steroid hormones profoundly influence behavioral response to alcohol, yet the role of unconventional non-genomic steroid signaling in this process is unknown. I discovered that Drosophila DopEcR, a G-protein coupled receptor (GPCR) activated by dopamine or the major insect steroid hormone ecdysone, plays a critical role in ethanol-induced behaviors. DopEcR mutants took longer to sedate when exposed to ethanol vapor, and post-eclosion expression of DopEcR-RNAi phenocopied mutant resistance. DopEcR was necessary in particular neuronal subsets, including cholinergic and peptidergic neurons, and promoted ethanol sedation by suppressing epidermal growth factor/extracellular signal-regulated kinase signaling. In adult flies, ecdysone negatively regulated DopEcR-mediated ethanol-induced sedation. We also found that DopEcR inhibits ethanol-induced locomotion, a conserved dopaminergic behavior. Together, these findings provide novel insight into how an unconventional steroid GPCR interacts with multiple downstream signaling cascades to fine tune behavioral response to alcohol. Despite an established link between epilepsy and sleep behavior, it remains unclear how epileptogenic mutations affect sleep and seizure susceptibility. To address this, I examined the rest/wake behavior of two fly models of epilepsy with paralytic voltage-gated sodium channel mutations known to cause human generalized epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS). GEFS+ and DS flies display heat-induced seizure susceptibility, but at normal temperatures I found that both mutants had exaggerated nighttime sleep behavior. GEFS+ sleep was more resistant to pharmacologic and genetic reduction of GABA transmission as compared to control’s response. This finding is consistent with augmented GABAergic suppression of wake-promoting pigment-dispersing factor (PDF) neurons in GEFS+ mutants. Contrastingly, DS sleep was almost completely resistant to pharmacologic GABA reduction, suggesting that PDF neurons are incapable of functioning despite disinhibition. The sleep of both GEFS+ and DS flies was largely suppressed, but not eliminated, by scotophase light, highlighting the importance of light stimulus and circadian signals in the manifestation of their phenotypes. Following sleep deprivation, GEFS+ and DS mutants failed show to homeostatic rebound. Sleep loss also unexpectedly reduced the seizure susceptibility of GEFS+ flies. This study revealed the sleep architecture of Drosophila voltage-gated sodium channel mutants and provides a unique platform in which to further study the sleep/epilepsy relationship.

Epileptic syndromes with continuous spikes and waves during slow sleep (CSWS) are age-related epileptic encephalopathy characterized by the development of various psychomotor regressions in close temporal concordance with the appearance of the electroencephalogram (EEG) pattern of CSWS (Tassinari et al. 2000). This EEG pattern consists in sleep-related activation and diffusion of spike-wave discharges during usually more than 85% of non-rapid eye movement (non-REM) sleep (Tassinari et al. 2000). <p>A minority of the CSWS cases has been associated to cortical or thalamic lesions (symptomatic cases), while in the other cases, the aetiology is unknown. We reported two families combining benign childhood epilepsy with centro-temporal spikes (BCECS), which is the most common form of idiopathic epilepsy in childhood, and cryptogenic epilepsy with CSWS in first-degree relatives. As idiopathic epilepsies are by definition epilepsies related to a genetic predisposition, these data suggests the existence of a continuum ranging from asymptomatic carriers of centro-temporal spikes to cryptogenic epilepsies with CSWS. This hypothesis is further supported by common clinical characteristics between BCECS and epilepsies with CSWS (Fejerman et al. 2000).<p>Epileptic syndromes with CSWS are characterized by an acute phase defined by the emergence of psychomotor deficits, various types of seizures and CSWS activity at around three to eight years of age (Holmes and Lenck-Santini, 2006; Veggiotti et al. 2001). This acute phase is followed by a recovery phase in which patients’ clinical condition improves together with the remission of CSWS pattern, which spontaneously occur at around 15 years of age but may be prompted by using antiepileptic drugs (AED) including corticosteroids (Holmes and Lenck-Santini, 2006; Veggiotti et al. 2001). This biphasic evolution suggests that CSWS activity largely contributes to the psychomotor deficits observed in these patients (Holmes and Lenck-Santini, 2006; Van Bogaert et al. 2006). However, some authors still consider CSWS activity as an epiphenomenon reflecting the underlying brain pathology, rather than the direct cause of the psychomotor regression (Aldenkamp and Arends, 2004). The pathophysiological mechanisms of how CSWS activity could actually lead to psychomotor regression are still poorly understood.<p>Functional cerebral imaging techniques such as positron emission tomography (PET) or functional magnetic resonance imaging (fMRI), represent unique ways to non-invasively study the impact of epileptic activity on normal brain function. The PET technique using [18F]-fluorodeoxyglucose (FDG) gives information about the regional neuronal glucose consumption via the neurometabolic coupling while the fMRI technique studies the regional perfusional changes directly related to specific events of interest via the neurovascular coupling. We applied both FDG-PET and EEG combined with fMRI (EEG-fMRI) techniques to epileptic children with CSWS to better approach the functional repercussions of CSWS activity on neurophysiological functions and to determine the potential pathophysiological link between CSWS activity and psychomotor regression.<p>In a first FDG-PET study, we determined the regional cerebral glucose metabolic patterns at the acute phase of CSWS in 18 children. We found three types of metabolic patterns: the association of focal hypermetabolism with distinct hypometabolism in 10 patients, focal hypometabolism without any associated area of increased metabolism in five children, and the absence of any significant metabolic abnormality in three patients. The hypermetabolic brain areas were anatomically related to an EEG focus. This anatomical relationship was clearly less consistent for hypometabolic regions. The metabolic abnormalities involved mainly the associative cortices. The metabolic heterogeneity found in these children could be due to the use of corticosteroids before PET as it was significantly associated with the absence of focal hypermetabolism. At the group level, patients with at least one hypermetabolic brain areas showed significant increased metabolism in the right parietal region that was associated to significant hypometabolism in the prefrontal cortex. This finding was interpreted as a phenomenon of remote inhibition of the frontal lobes by highly epileptogenic and hypermetabolic posterior cortex. This hypothesis was supported by effective connectivity analyses which demonstrated the existence of significant changes in the metabolic relationship between these brain areas in this group of children compared to the control group or to the group of children without any significant hypermetabolic brain area. <p>This remote inhibition hypothesis would be reinforced by the demonstration, at the recovery phase of CSWS, of a common resolution of hypermetabolism at the site of epileptic foci and hypometabolism in distant connected brain areas. We thus performed a second FDG-PET study to determine the evolution of cerebral metabolism in nine children recovering from CSWS. At the acute phase of CSWS, all children had a metabolic pattern characterized by the association of focal hypermetabolism with distinct focal hypometabolic areas. The evolution to CSWS recovery was characterized by a complete or almost complete regression of both hypermetabolic and hypometabolic abnormalities. At the group level, the altered effective connectivity found at the acute phase between focal hypermetabolism (centro-parietal regions and right fusiform gyrus) and widespread hypometabolism (prefrontal and orbito-frontal cortices, temporal lobes, left parietal cortex, precuneus and cerebellum) markedly regressed at recovery. These results were of particular interest because they strongly suggested that the metabolic abnormalities observed during the acute phase of CSWS were mainly related to the neurophysiological effects of CSWS activity and not to the underlying cause of the epileptic disease. Moreover, this study confirmed that phenomena of remote inhibition do occur in epileptic syndromes with CSWS. <p>EEG-fMRI is a functional cerebral imaging technique that allows non-invasive mapping of haemodynamic changes directly associated to epileptic activity. In a first EEG-fMRI study, we determined the clinical relevance of the perfusional changes linked to interictal epileptic discharges in a group of seven children with pharmacoresistant focal epilepsy. This study showed that the EEG-fMRI technique is a promising tool to non-invasively localize the epileptic focus and its repercussion on normal brain function in children with epilepsy. Then, to further demonstrate the involvement of CSWS activity in the neurophysiological changes detected by FDG-PET, we used the EEG-fMRI technique to study the perfusional changes directly related to the epileptic activity in an epileptic girl with CSWS. This patient developed a cognitive and behavioural regression in association with a major increase in frequency and diffusion of the spike-wave discharges during the awake state (spike index: 50-75%) and non-REM sleep (spike index: 85-90%). The patient’s neuropsychological profile was dominated by executive dysfunction and memory impairment. During runs of secondarily generalized spike-wave discharges, EEG-fMRI demonstrated deactivations in the lateral and medial fronto-parietal cortices, posterior cingulate gyrus and cerebellum together with focal relative activations in the right frontal, parietal and temporal cortices. These results suggested that the neuropsychological impairment in this case could be related to specific cortical dysfunction secondary to the spread of the epileptic activity from focal hypermetabolic foci. <p>Taken together, both FDG-PET and EEG-fMRI investigations performed in epileptic children with CSWS have shown increases in metabolism/perfusion at the site of the epileptic focus that were associated to decreases in metabolism/perfusion in distinct connected brain areas. These data highly suggest that the neurophysiological effects of CSWS activity are not restricted to the epileptic focus but spread to connected brain areas via a possible mechanism of surrounding and/or remote inhibition. This mechanism is characterised by an epilepsy-induced inhibition of neurons that surround or are remote from the epileptic focus and connected with it via cortico-cortical or polysynaptic pathways (Witte and Bruehl, 1999). The existence of surrounding and remote inhibition phenomena have been well documented in different types of animal models of focal epilepsy using various functional cerebral imaging methods such as autoradiography or optical imaging (Bruehl et al. 1998; Bruehl and Witte, 1995; Witte et al. 1994). Their occurrence in human epilepsy have also been suspected in temporal or extra-temporal lobe epilepsies using FDG-PET, EEG-fMRI or single photon emission computed tomography (SPECT) (Blumenfeld et al. 2004; Schwartz and Bonhoeffer, 2001; Van Paesschen et al. 2003; Van Paesschen et al. 2007). Moreover, the demonstration of the regression of distant hypometabolic areas after surgical resection or disconnection of the epileptic focus further suggest that such inhibition mechanism do occur in epilepsy (Bruehl et al. 1998; Jokeit et al. 1997). On a clinical point of view, the demonstration of the existence of such inhibition mechanisms in epilepsies with CSWS brings new important insights for the understanding of the pathophysiological mechanisms involved in the psychomotor regression observed in these conditions. Indeed, these data highly suggest that the psychomotor regression is not only related to the neurophysiological impairment at the site of the epileptic foci but also to epilepsy-induced neurophysiological changes in distant connected brain areas. <p><p><br>Doctorat en Sciences médicales<br>info:eu-repo/semantics/nonPublished

Background: good sleep architecture, particularly of the NREM phase, is fundamental for the development and maintenance of various cognitive functions. A fragmentation in this specific phase could be responsible for the reported cognitive difficulties in patients with Sleep-related Hypermotor Epilepsy (SHE) as perception of non-restorative sleep, daytime sleepiness and negative impact on cognitive functions, showing the fundamental role of frontal lobe in structuring the subject's personality and its processes higher mental. Also NREM sleep Parasomias is characterezed by an instability in this phase which may be responsible for daytime symptoms reported by patients such as excessive daytime sleepiness and mood changes. In this case, cognitive functioning is generally conserved; although patients may report concentration difficulties and decreasing performances attention-demanding task. Our study has as objectives to evaluate the behavioral-cognitive functioning of patients with SHE and NREM Parasomnias and to study the possible role of pharmacological treatments on cognitive functioning in SHE patients. Participants: This cohort study was conducted in the Center for the Diagnosis and Treatment of Sleep Disorders at the University Hospital of Monserrato (Cagliari) between March 2016 and June 2019. We recruited 16 patients, (9 Male and 7 Female, average age 33.56 ± 12.23, average education 12.5 ± 3.10), with SHE video-PSG confirmed. To evaluate the possible role of pharmacological treatments on cognitive functioning, we identified 13 patients in drug treatment with SHE video-PSG confirmed between 2013-2015 (6 M and 7 F, average age 42 ± 14.96, average education 12.38 ± 3.45). We then recruited 11 patients, 3 males and 8 Females with NREM parasomnias video-PSG confirmed (average age 32, 91 ± 10.82, average education 13.55 ± 3.33). To verify statistic differences, we recruited a control group of healthy volunteers matched by age, sex and education with each patient. Materials and methods: a battery of standardized neuropsychological tests was used to explore the cognitive functions as attention, executive functions, visual-constructive and visuo-spatial skills, memory, language and logical reasoning skills. Subjective behavioral questionnaires were administered to evalue quality of night's sleep, daytime sleepiness, comorbidity with other sleep disorders, depressive symptoms and anxiety. Discussion: SHE patients show an implication in executive and memory functions with an inhibiting interference, cognitive flexibility, ability to recover informations based on effective research strategies, verbal and visuo-spatial episodic memory. Behavioral assessment shows an involvement of state anxiety on the initial performance which is reduced as the evaluation proceeds. The perception of “acting" during sleep and the unpleasant sensation in the lower limbs that inevitably affect the affective area, as demonstrated by the presence of depressive symptoms. Compared to the role of antiepileptic therapy on cognitive functioning in patients with SHE, results obtained show an involvement of the verbal episodic memory. Compared behavioral-cognitive NREM Parasomnia profile, in accordance with the literature, the subjects don’t show , an impairment of the cognitive functions investigated, despite the reported attentional difficulties, it was found that all patients with Parasonnie NREM had a positive outcome on the RBD test. Conclusions: results show an executive and memory implication in SHE patients. Presence of a mood deflection confirm the negative impact of nighttime crises on a relational and social level reported by patients. Antiepileptic therapy in SHE could induce positive effects on the cognitive functions, depending on the characteristics of the individual patient. Compared to NREM Parasomnias, it is not possible to assert a cognitive involvement.

Il sistema colinergico proietta in modo diffuso alla corteccia prefrontale (PFC) matura e sostiene l’attivazione corticale durante la veglia e il sonno REM. Il ruolo dei recettori nicotinici (nAChRs) nel mediare questi processi è sempre più riconosciuto. Inoltre, i nAChRs regolano anche lo sviluppo dei circuiti corticali durante le prime settimane di vita. Innanzitutto abbiamo studiato topi esprimenti β2-V287L, una subunità mutata del nAChR associata all’epilessia notturna autosomica dominante del lobo frontale (ADNFLE). β2-V287L svolge la sua azione epilettogenica alterando la stabilizzazione sinaptica durante le fasi critiche della maturazione circuitale, infatti, la sua espressione durante le prime due settimane di vita è necessaria per lo sviluppo del fenotipo epilettico nel topo adulto. Questa fase critica, inoltre, coincide con lo switch del GABA da eccitatorio a inibitorio, determinato dalla diminuzione progressiva del rapporto tra l’espressione del cotrasportatore-1 Na+/K+/Cl- (NKCC1) e del cotrasportatore-2 (KCC2) K+/Cl-. La regolazione di questi trasportatori nella PFC e nel talamo è ancora largamente sconosciuta. Abbiamo indagato la distribuzione di NKCC1 e KCC2 in topi wild-type (WT) durante lo sviluppo. I livelli di entrambi i trasportatori aumentano progressivamente durante le prime due settimane di vita sia nella PFC che nella corteccia somato-sensoriale. Alla nascita, KCC2 è localizzato principalmente nei corpi cellulari neuronali e in seguito migra verso le membrane somato-dendritiche. In topi esprimenti β2-V287L, i livelli di KCC2 nel V strato della PFC a 8 giorni (P8) sono inferiori rispetto ai topi controllo, ma raggiungono livelli di espressione maggiori a P60. Anche la tempistica dello switch del GABA, misurato tramite patch perforato, risulta ritardato nel V strato della PFC nei topi mutati. Al momento della nascita NKCC1 e KCC2 sono molto espressi nel neuropilo dei nuclei talamici, indipendentemente dal genotipo. Il loro livello d’espressione rimane alto nei nuclei sensoriali nell’adulto, mentre KCC2 diminuisce significativamente nel nucleo reticolare a P40. Tale riduzione è più pronunciata nei topi esprimenti β2-V287L. Questi risultati indicano che i nAChRs contenenti la subunità β2 interagiscono con KCC2 durante la sinaptogenesi e questo può contribuire alla patogenesi dell’ADNFLE. In secondo luogo, abbiamo esplorato alcuni aspetti della complessa interazione tra i principali neurotrasmettitori che partecipano all’attivazione corticale, ovvero acetilcolina (ACh), noradrenalina (NE) e oressina A (OrxA), allo scopo di caratterizzare il loro effetto sull’eccitabilità del V strato della PFC. In particolare, tramite patch-clamp in topi WT adulti, abbiamo indagato il loro ruolo nel modulare il rilascio di glutammato sui neuroni piramidali del V strato. La somministrazione tonica di ACh stimola il rilascio di glutammato, principalmente attraverso i nAChRs contenenti la subunità α4. Inoltre, l’OrxA è in grado di stimolare il rilascio di glutammato sui neuroni piramidali attivando i recettori 1 dell’Orx (OrxR1). Anche basse concentrazioni di NE (10 nM) sono efficaci nell’aumentare il rilascio di glutammato. Possiamo concludere che questi neuromodulatori cooperano nel regolare la trasmissione glutammatergica nella PFC. Tale interazione potrebbe essere cruciale nella regolazione dei meccanismi cellulari alla base delle funzioni cognitive ed esecutive svolte da questa regione. Questo avviene sia in condizioni normali che patologiche, le quali sono spesso accompagnate da alterazioni dei ritmi theta, generati da dinamiche proprie dei neuroni piramidali. Questi risultati possono aiutare a comprendere la complessa regolazione dei microcircuiti della PFC, e pongono le basi per ulteriori indagini sui meccanismi patogenetici responsabili di anomalie corticali, tipiche di alcuni disordini legati al sonno, come l’epilessia frontale e la narcolessia con cataplessia.<br>The cholinergic system extensively innervates mature prefrontal cortex (PFC) and is critical to sustain cortical activation during wakefulness and REM sleep. The implication of nicotinic receptors (nAChRs) in these processes is increasingly recognized. Moreover, nAChRs regulate developing cortical circuits during the first postnatal weeks. First, we studied mice expressing β2-V287L, a mutant subunit of the nAChR linked to Autosomal Dominant Nocturnal Frontal Lobe Epilepsy (ADNFLE). β2-V287L exerts the epileptogenic action by altering the synaptic stabilization during sensitive phases of network maturation, since its expression during the first two postnatal weeks is necessary to develop the epileptic phenotype. The peak of postnatal expression of nAChRs coincides with the excitatory to inhibitory GABAergic switch, which is determined by the progressive decrease in the ratio between the expression of the Na+/K+/Cl- cotransporter-1 (NKCC1) and the K+/Cl- cotransporter-2 (KCC2). How these transporters are regulated in PFC and thalamus is largely unknown. We first studied the distribution of NKCC1 and KCC2 in developing wild-type (WT) mice. The amount of NKCC1 and KCC2 in PFC and somatosensory cortex progressively increased during the first two postnatal weeks. NKCC1 was found in neurons as well as astrocytes. KCC2 was mainly localized in neuronal somata at birth, and subsequently migrated to the somatodendritic membranes. Next, in mice expressing β2-V287L, the KCC2 amount in PFC layer V was lower than in the control littermates at postnatal day 8 (P8), but reached higher amounts by P60. Consistently, the time course of the GABAergic switch was delayed in PFC layer V of mice carrying β2-V287L, as measured by perforated patch method. Irrespective of genotype, NKCC1 and KCC2 were highly expressed in the neuropil of thalamic nuclei at birth. Their amount remained high in the adult sensory nuclei, whereas a significant decrease of KCC2 was observed in the reticular nucleus by P40. Such a decrease was more pronounced in mice expressing β2-V287L. Our results indicate that β2-containing nAChRs interact with KCC2 during synaptogenesis as well as in mature circuits, which may contribute to the pathogenesis of ADNFLE. Second, we explored some aspects of the complex interplay between the main neurotransmitters involved in cortical arousal, i. e. acetylcholine (ACh), norepinephrine (NE) and orexin A (OrxA), in order to characterize their combined effect on the PFC layer V circuit. In particular, by patch-clamp methods, we investigated how these neurotransmitters regulate glutamate release onto pyramidal neurons in PFC layer V of adult wild-type mice. Tonic administration of ACh stimulated glutamate release, mainly through α4-containing nAChRs. Moreover, OrxA increased the glutamate release onto pyramidal neurons, through Orx Receptor 1 (OrxR1). Low concentrations of NE (10 nM) were also effective in increasing glutamatergic release. We conclude that these neuromodulators cooperate in regulating glutamatergic transmission in PFC. Such interaction may be crucial in the cellular mechanisms underlying the cognitive and executive functions in this area, in normal and pathological conditions, which are often accompanied by alterations in the theta rhythms, largely determined by pyramidal neurons dynamics. These results may yield new insights into the complex regulation of the PFC microcircuit and lay the basis for further investigations on the pathogenic mechanisms responsible of altered cortical activity in sleep-related disorders such as frontal epilepsy and narcolepsy with cataplexy.

Il sistema di regolazione ascendente è costituito da diversi nuclei situati nel tronco cerebrale, nel prosencefalo basale e nell'ipotalamo. Questi nuclei regolano l'eccitazione, gli stati attentivi e coscienti, nonché l’attivazione autonomica. Il sistema di regolazione ascendente agisce a tutte le scale temporali e questi livelli di controllo sono raggiunti attraverso una varietà di meccanismi d'azione dei neurotrasmettitori, con diversi tempi e durate. Qualsiasi alterazione del sistema modulatorio ascendente può influire sulla sua capacità di generare i ritmi e quindi influenzare la regolazione e la stabilità del sonno/veglia e gli stati comportamentali, così come la cognizione. Le due malattie che ho studiato sono: l'epilessia ipermotoria correlata al sonno autosomica dominante (ADSHE), spesso legata a disfunzione colinergica, e la narcolessia con cataplessia (NC), causata da carenza di oressina. Sia l'ADSHE che la narcolessia possono essere definite ritmopatie, poiché i loro sintomi distintivi sono disfunzioni del ritmo dell'attività cerebrale. In questa tesi, ho caratterizzato le alterazioni funzionali dei recettori nicotinici dell'acetilcolina (nAChR) contenenti subunità α2 mutanti legate all'ADSHE o all’epilessia del lobo temporale laterale autosomico dominante. Le mutazioni hanno causato una perdita di funzione del canale suggerendo che le mutazioni su CHRNA2 sono più comunemente legate a sindromi epilettiche di quanto si pensasse in precedenza. Abbiamo studiato le alterazioni morfo-funzionali nello strato V della corteccia prefrontale di topi che esprimono la subunità β2V287L legata all'ADSHE. La sua espressione era correlata ad alterazioni morfologiche nella ramificazione dendritica dei neuroni piramidali, nonché a una diminuzione del 10% circa dello spessore della corteccia. I topi mutanti hanno mostrato correnti nicotiniche somatiche più grandi negli interneuroni SOM+ regular spiking insensibili alla serotonina (in gran parte cellule di Martinotti). Ciò può spiegare perché le convulsioni possono essere facilitate dal basso tono colinergico tipico del sonno NREM e perché la somministrazione di nicotina può essere palliativa nei pazienti. Ho dimostrato l'efficace eliminazione di Ox2R nei topi Ox2R-Δ, creati da Anne Vassalli. Ho anche valutato se i topi Ox2R-flox avessero un Ox2R funzionalmente equivalente ai topi di controllo C57BL6/J. Le risposte agli agonisti Ox2R dei neuroni istaminergici del nucleo tuberomammillare dell'ipotalamo hanno confermato questo modello murino come uno strumento affidabile per sezionare la funzione specifica di Ox2R nei circuiti cerebrali. Abbiamo studiato la modulazione Orx del microcircuito in Fr2 e PFC mediale. Le EPSC sono stimolate da OrxA sui neuroni piramidali dello strato V. L'effetto è mediato da Ox1Rs e dipende da un meccanismo presinaptico che coinvolge meccanismi indipendenti e dipendenti dal canale CaV. OrxB esercita un effetto combinato su Ox2Rs e Ox1Rs, producendo un effetto inibitorio. Ox2R ha un distribuzione diffusa sui corpi cellulari e nel neuropilo, e l'analisi di colocalizzazione ha mostrato un'innervazione oressinergica più densa degli interneuroni SOM+ GABAergici, rispetto alle cellule PV+ e una maggiore espressione di Ox2R sui neuroni SOM+. Questi interneuroni contribuiscono alla generazione del ritmo θ nella neocorteccia e nell'ippocampo, quindi le oressine potrebbero regolare la ritmogenesi θ nella PFC. Infine, abbiamo studiato le ragioni dell'aumentata eccitabilità della via VTA-septo-ippocampale mostrata dai topi Ox2RDat-CKO. Ciò potrebbe essere dovuto a una specifica regolazione Ox2R-dipendente dei neuroni VTADA, probabilmente a valle di quelli VTADA: quando la sensibilità all'oressina Ox2R-dipendente dei neuroni VTADA è compromessa, le cellule VTADABA non sono più in grado di bloccare l’attività θ intrinseca in ippocampo, sia attraverso l'attivazione di VTADA che attraverso un altro meccanismo sconosciuto.<br>The brain ascending regulatory system is a complex of interconnected neuronal nuclei of different neurochemical nature, located in the brainstem, basal forebrain and hypothalamus. These nuclei regulate arousal, attentive and conscious states as well as in the autonomic state regulation. The brain ascending regulatory system acts at all scales in the brain and these levels of control are achieved through a variety of neurotransmitters’ mechanisms of action, having different time lags and durations. Any defect or alteration of the brain ascending modulatory system may impact on its ability to generate and sustain rhythms and thus affect the regulation and stability of sleep/wake and behavioural states, as well as cognition. The two diseases I have studied are of this kind: Autosomal Dominant Sleep-related Hypermotor Epilepsy (ADSHE), often linked to cholinergic dysfunction, and narcolepsy with cataplexy (NC), caused by orexin deficiency. Both ADSHE and narcolepsy can be defined as rhythmopaties, since their defining symptoms are dysfunctions of brain activity rhythm. In this thesis, I characterized the functional alterations of nicotinic acetylcholine receptors (nAChRs) containing mutant α2 subunits linked to ADSHE or Autosomal Dominant Lateral Temporal Lobe Epilepsy. The mutations caused a loss-of-function of the channel suggesting that CHRNA2-affecting mutations are more commonly linked to epileptic syndromes than previously thought, especially loss-of-function ones. We also studied the morpho-functional alterations in the prefrontal cortex layer V of mice conditionally expressing the ADSHE-linked β2V287L subunit. Its expression was correlated to minor morphological alterations in pyramidal neurons’ dendritic ramification, as well as to a ~10% decrease of prefrontal cortex thickness. Mutant mice showed larger somatic nicotinic currents in regular spiking SOM+ interneurons insensitive to serotonin (largely Martinotti cells). These results may explain why seizures may be facilitated by the low cholinergic tone typical of NREM sleep and why nicotine administration can be palliative in patients. I demonstrated the effective deletion of Ox2R in the Ox2R-Δ mice, created by Dr. Anne Vassalli. I also assessed if the Ox2R-flox mice had functionally equivalent Ox2R as C57BL6/J control mice. The responses to Ox2R agonists of the classical Ox2R-expressing neuronal type – the histaminergic neurons of the ventral tuberomammillary nucleus of the hypothalamus – confirmed this mouse model as a reliable tool to dissect the specific function of Ox2R in the cerebral circuits. We studied the Orx modulation of pyramidal and interneuronal microcircuits of Fr2 and medial PFC. OrxA stimulated EPSCs on layer V pyramidal neurons. The effect is mainly mediated by Ox1Rs and depends on a presynaptic mechanism involving CaV channel-dependent and independent mechanisms. OrxB exerts a combined effect on Ox2Rs and Ox1Rs, producing an inhibitory effect that is reverse compared to that of the activation of Ox2Rs or Ox1Rs alone. Immunocytochemistry showed a diffuse Ox2R distribution on both cell bodies and neuropil and colocalization analysis showed a denser orexinergic innervation of SOM+ GABAergic interneurons, as compared to PV+ cells; a higher expression of Ox2R on SOM+ neurons. These interneurons have been shown to contribute to the generation of θ band rhythm in the neocortex and hippocampus, so orexins could regulate θ rhytmogenesis in the PFC. Finally, we investigated the reasons of the increased excitability of the VTA-septo-hippocampal pathway shown by Ox2RDat-CKO mice. Our data suggest that it may be due to a specific Ox2R-dependent regulation of VTADA neurons, probably downstream of VTAGABA ones: when the Ox2R-dependent orexin sensitivity of VTADA neurons is impaired, the VTAGABA cells are no longer able to block the intrinsic θ-resonant hippocampal activity, either through VTADA activation or via another unknow mechanism.

Accelerated long-term forgetting (ALF) is a recently described memory impairment associated with epilepsy. Patients with ALF appear to learn and initially retain new information normally, but forget it at an accelerated rate over subsequent days. ALF can have a profound impact on the lives of the people who suffer from it, but it is also of theoretical interest. In particular, the study of this disorder may provide insight into the mechanisms of memory consolidation. ALF is especially prevalent in transient epileptic amnesia (TEA), an epileptic syndrome in which the seizure focus is thought to be the medial temporal lobes (MTL). The MTL house the hippocampus and a number of other structures critical for declarative memory function. The aims of this doctoral thesis were to investigate which aspects of memory function are disrupted in patients with TEA-associated ALF, and to shed light on the neural basis of the memory impairment. Slow wave sleep (i.e. deep sleep) is known to exacerbate epileptic activity. It is also thought to play a key role in the consolidation of declarative memory. The most commonly posited explanation of ALF is the disruption of sleep- dependent memory consolidation. However, it remains possible that ALF is caused by a subtle problem with encoding that usually goes undetected until delayed memory tests. The results of this thesis demonstrate that sleep can actually benefit memory retention in TEA ALF patients just as much as it does in healthy people, and that it is not necessary for the retention interval to contain sleep in order for ALF to be seen. However, the relationship between slow wave sleep and memory was found to be abnormal in these patients. The amount of slow wave sleep, and the power in the slow oscillation frequency range, during the post-learning night correlated negatively with the benefit of that night of sleep for memory retention. Furthermore, resting-state brain activity patterns thought to reflect post-encoding memory reprocessing were found to correlate negatively with subsequent memory performance in these patients. Another chapter of this thesis provides evidence that TEA ALF patients encode memories abnormally; these patients showed reduced activity in the left hippocampus while viewing stimuli that they went on to forget. Furthermore, this encoding-related brain activity correlated with their long-term forgetting. The final experimental chapter reports a correlation in these patients between grey matter in the left hippocampus and long-term forgetting, which cannot entirely account for the encoding-related brain activity results. The hippocampus and its surrounding structures are thought to be critical to our ability to discriminate between similar stimuli and events. An intriguing hypothesis consistent with the pattern of results in this thesis is that ALF is caused by a functional impairment of the MTL that results in a diminished capacity to distinguish between similar experiences, ultimately causing memory problems; abnormally formed memories may interact with new material and memory consolidation processes in an aberrant manner, leading to retrieval deficits.

INTRODUÇÃO: As relações entre sono e epilepsia são complexas e de grande importância clínica. A melhor compreensão das inúmeras lacunas que permeiam essa relação reforçaria os alicerces para o desenvolvimento de abordagens terapêuticas mais eficazes que pudessem contribuir para o bem-estar do paciente portador de epilepsia e transtornos do sono. OBJETIVO: O presente estudo teve como principal objetivo o estudo comportamental e a caracterização eletrofisiológica do ciclo vigília-sono (CVS) de ratos adultos tornados epilépticos por pilocarpina. MÉTODO: Ratos Wistar machos (N=6), tornados epilépticos após status epilepticus (SE) induzido por pilocarpina e não epilépticos (N=6) foram submetidos à cirurgia extereotáxica para implante de elétrodos bipolares nas áreas corticais (A3, somatosensorial) e hipocampais (CA1) de ambos os hemisférios. Registros contínuos de 24 horas foram submetidos à minuciosa análise visual e os seguintes parâmetros foram analisados: identificação e quantificação dos padrões eletrofisiológicos das fases do ciclo CVS; duração dos episódios oníricos ocorridos durante o sono dessincronizado (SD); padrão de ocorrência do CVS assim como do ciclo de sono (CS), e análise do volume do núcleo supraquiasmático. Os estudos da distribuição do CVS e comportamento onírico foram submetidos à Análise de Variância Multivariada - MANOVA, ao passo que as análises da ocorrência dos ciclos (CVS e CS) e volume do núcleo supraquiasmático foram submetidas ao teste da Análise de Variância (ANOVA) de dois fatores e ao teste de Mann- Whitney, respectivamente. RESULTADOS: Todas as fases do CVS foram identificadas nos ratos epilépticos. As fases da vigília e do sono eram permeadas por espículas e outros grafoelementos epileptiformes, como ondas delta espiculadas no SS e potenciais de alta frequência e baixa voltagem durante VA e o SD. Ao contrário do padrão de ocorrência típico das fases de vigília e sono em ratos não epilépticos, o grupo epiléptico apresentou diferenças significativas quanto à distribuição dessas fases em função do período. Foi observada redução significativa de VA (p<0,002) com concomitante aumento de SS (p<0,005) e vigília relaxada (VR) (p=0,021) no escuro, sendo que a VR era preponderante apenas na primeira metade da noite. Durante o dia, a quantidade de SS era maior no período da manhã (p<0,001), ao passo que houve redução do SD (p=0,002) concomitante com aumento de VA (p<0,001) no período da tarde.Os animais tornados epilépticos por pilocarpina apresentaram redução no padrão de ocorrência do CVS e CS (p=0,004 e p=0,003, respectivamente). Não houve diferença estatística na duração dos episódios oníricos, assim como no volume do núcleo supraquiasmático entre os grupos analisados (p>0,63 e p=0,47, respectivamente). CONCLUSÃO: Os animais epilépticos apresentaram alterações na arquitetura do CVS, bem como nos padrões de ciclicidade evidenciado pelas alterações de comportamento, especialmente no ciclo escuro. Esses fatos sugerem possível comprometimento estrutural e/ou funcional das circuitarias responsáveis pela geração e manutenção das fases de vigília e sono, assim como dos sistemas de temporização do CVS. Tomados em conjunto, os dados reproduziram anormalidades do CVS observadas em pacientes epilépticos, sugerindo que o presente modelo pode ser uma importante ferramenta para o estudo de mecanismos subjacentes à epilepsia do lobo temporal e sono.<br>INTRODUCTION: Relationships between sleep and epilepsy are complex and have great clinical importance as well. The full understanding of the various gaps present in this relationship would pave the ground for new studies that could generate new clinical approaches aiming to contribute to the well-being of the patient suffering from epilepsy and sleep disorders. OBJECTIVE: The present study aimed to carry out a behavioral analysis and electro-oscillographic characterization of the phases of sleep-wake cycle (SWC) of pilocarpine- induced epilepsy in adult rats. METHODS: Male Wistar rats that became epileptic after 60 days of pilocarpine-induced status epilepticus (SE) (N=6) and non epileptic ones (N=6) were submitted to extereotaxic surgery for implantation of bipolar electrodes in cortical (A3, somestesic) and hippocampal (CA1) areas in both hemispheres. Twenty-four hour continuous registers were submitted to detailed visual analysis and the following parameters were studied: identification and quantification of electrophysiological parameters of phases of SWC, duration of oniric episodes during desynchronized sleep (DS), the pattern of occurrence of SWC and cycles of sleep (CS). In addition, the volume of suprachiasmatic nuclei was investigated. To analyze the architecture of sleep-wake phases and oniric behavior, Multivariate Analysis of Variance-MANOVA was utilized, whereas the pattern of cycles (SWC and CS) and volume of suprachiasmatic were submitted to Analysis of Variance with 2 factors-Two-way ANOVA and Mann-Whitney test, respectively. RESULTS: In the epileptic rats all phases of SWC were identified. The phases of wake and sleep were permeated by spikes and graph elements epileptiforms such as spiked delta waves in SS and low frequency waves with high voltage during AW and SD phases. In contrast to the pattern of normal rhythmic activity evident in non-epileptic rats the epileptic group presented significant differences concerning distribution of the phases of SWC according to the period. In the dark cycle significant reduction of AW (p<0.002) was observed concomitantly with an increase of SS (p<0.005), while the relaxed wakefulness (RW) showed an increase during the first half of the night (p=0.021). In the light cycle, the SS was more prominent in the morning period (p<0.001), following by a reduction of DS (p=0.002) concomitantly with an increase of AW (p<0.001) during the afternoon in the epileptic group. The number of cycles with a regular sequence of each phase from awake to sleep (SWC) was significantly decreased (p=0.004), as was the number of cycles of sleep (p=0.003) in epileptic rats. No significant differences were found in duration of oniric episodes and volume of suprachiasmastic nuclei (p>0.63 e p=0.47, respectively) between non epileptic and epileptic groups. CONCLUSION: The data obtained revealed that after SE the epileptic animals presented some alterations in the SWC architecture as well as in the cyclicity patterns mainly in dark cycle. Such facts suggest a possible functional and/or structural impairment in the circuitry responsible for the generation of sleep and wake phases and in the SWC timing system. Taken together the data reproduced the abnormalities observed in patients, suggesting that the pilocarpine model is a suitable one to study sleep dysfunctions in temporal lobe epilepsy.

Nors Rolando epilepsijai (RE) būdinga gerybinė eiga, dalis sergančiųjų turi miego bei elgesio problemų. Nuosekliai ištyrėme 75 RE sergančius bei 32 lyginamosios grupės nesergančius epilepsija pacientus. Grupės nesiskyrė pagal amžių ir lytį. Suskirstėme sergančiuosius RE į dvi grupes pagal priepuolių pasikartojimą per paskutinius 6 mėnesius. Elgesio sutrikimai buvo vertinami pasitelkiant CBCL (angl. Child Behavior Checklist) klausimyną, miego sutrikimai-pagal vaikų miego sutrikimų skalę (SDSC) (angl. Sleep Disturbance Scale for Children). Vertinome miego ir elgesio problemas bei jų sąsajas su klinikiniais, EEG duomenimis bei vizualinės-motorinės reakcijos laiko duomenimis. Bendradarbiaudami su Vilniaus universiteto Matematikos ir informatikos fakultetu rankiniu ir automatiniu būdu tyrėme pacientų EEG. Tik tiems RE pacientams, kuriems buvo priepuolių per paskutinius 6 mėn., nustatėme patikimai aukštesnius SDSC klausimyno įverčius (padidintą mieguistumą, kvėpavimo sutrikimus miego metu, miego- budrumo ritmo sutrikimus, ilgesnę miego latenciją) bei patikimai aukštesnius CBCL klausimyno rodiklius (socialinių sunkumų, mąstymo sunkumų, dėmesio sunkumų, agresyvaus elgesio bei bendrų sunkumų skalių įverčius). Elgesio problemos buvo susiję su ilgesne epilepsijos trukme, sunkesniais ir dažnesniais priepuoliais, miego problemomis bei miego EEG pakitimais (>35/min pikų kiekiu bei pikų lokalizacija ir kitose nei centrotemporalinės srityse). Budrumo EEG nustatytas >17/min pikų kiekis buvo... [toliau žr. visą tekstą]<br>Although patients with benign Rolandic epilepsy (RE) exhibit a benign course of the disease, some of them display sleep and behavioural problems. Seventy five patients with RE, aged 6–11 years, were included in this study. The patients were divided into two subgroups according to the presence of seizures over the preceding 6 months. The comparison group comprised 32 patients without epilepsy and with similar characteristics in terms of age and sex. All patients underwent evaluation of sleep (Sleep Disturbance Scale for Children) and behaviour (Lithuanian version of Child Behaviour Checklist). We examined the sleep and behavioural problems in correlation with the clinical data, EEG data, and simple visual-motor reaction time data. We automatically and manually analysed EEG in the collaboration with Vilnius University Faculty of Mathematics and Informatics. Only patients who had had seizures over the preceding 6 months displayed significantly higher scores for sleep problems (disorders of excessive daytime sleepiness, disorders of sleep breathing, and disorders of sleep-wake transition, longer sleep onset latency), and behavioural problems (social problems, thought problems, attention problems, and aggressive behavior) than the patients of the comparison group. Behavioural problems were associated with the longer epilepsy duration, more frequent and more severe seizures, sleep problems and sleep EEG data (spike frequency >35/min and spike focus, spreading to the other than... [to full text]

Sleep-related Hypermotor Epilepsy (SHE) is a genetically heterogeneous epilepsy syndrome. Differences in epilepsy phenotype/endophenotype were associated with mutations in specific genes. However, the genes identified so far cumulatively account for 25% of cases. Moreover, systematic neuropsychological investigations on comprehensive SHE cohorts are lacking. This study provides an accurate clinical, genetic and neuropsychological characterization of a large cohort of patients diagnosed with SHE according to reliable diagnostic criteria. A subgroup underwent a preliminary screening, partly performed by dHPLC to exclude mutations in CHRNA4, CHRNB2, CHRNA2. Using a number of genetic strategies, we identified causative mutations in 10.4% of our cases. The mutation frequencies were 2.3% for KCNT1 (CI: 0.3-8.1%), 5.9% for GATOR1-complex genes (CI: 2.0-13.3%), 3.1% for CHRNA4 (CI: 0.6-8.8%) and 1.7% for SCN1A (CI 0-8.9%). WES analysis allowed the identification of a novel epilepsy gene, NPRL2, coding a component of GATOR1, a negative regulator of mTOR pathway. Altogether, mutations in the GATOR1 complex genes DEPDC5 and NPRL2 account for the majority of our cases (6%). Genotype-phenotype correlations confirmed their association with focal cortical dysplasia, higher rates of drug-resistance, aura and seizures in wakefulness, with relevant implications in diagnostic and treatment strategies. Moreover, we confirm that mutations in KCNT1 are implicated in severe forms with intellectual disability and psychiatric disorders. The unexpected detection of CHRNA4 mutations highlighted the low sensitivity of dHPLC assay. The systematic neuropsychological study showed that neurocognitive deficits are not uncommon in SHE. Mutated patients scored significantly lower at WAIS, supporting a crucial role of genetics in cognitive deficit by different biological mechanisms and molecular pathways. About 47% of patients of normal intelligence showed some degree of cognitive dysfunction. The profile of neuropsychological impairment was characterized by significant worse scores in verbal IQ, deficits in memory and in selected executive functions, with preserved shifting abilities and cognitive flexibility.

Avec plus de 30 millions de personnes touchées, la maladie d'Alzheimer (MA) est la démence la plus répandue dans le monde. Des recherches sur des modèles murins de la MA ont montré que le déséquilibre entre excitation et inhibition cérébrales provoque des activités épileptiques qui pourraient jouer un rôle la physiopathologie de cette maladie. Des études cliniques ont depuis montré que des activités épileptiques peuvent également être présentes jusqu'à chez 50% des patients atteints de MA, mais qu'elles peuvent passer inaperçues en raison de leur nature silencieuse et de leur survenue essentiellement nocturne. Par conséquent, la première partie de ce travail correspond à une étude préclinique dans laquelle nous avons cherché à caractériser (I) ces activités épileptiques au cours du cycle veille-sommeil chez la souris Tg2576 (modèle de la MA) tout au long de la vie et (II) ses mécanismes sous-jacents. Nous avons observé des activités épileptiques uniquement pendant le sommeil, et particulièrement pendant le sommeil paradoxal (SP). De plus, ces activités épileptiques surviennent sur la phase du rythme thêta du SP où les cellules pyramidales ont le plus de probabilité de déclencher des potentiels d'action, ce qui suggère une sous-inhibition potentielle - conformément à des résultats antérieurs de notre laboratoire. Finalement, ces activités épileptiques semblent contrebalancées par la noradrénaline via les récepteurs du type alpha1-AR pendant l'éveil et en partie pendant le sommeil lent, et seraient démasquées durant le SP quand les cellules noradrénergiques cessent leur activité. Étant donné l'atteinte précoce du centre noradrénergique chez les patients atteints de MA, cela pourrait également avoir des implications cliniques importantes. Dans la deuxième partie, les objectifs étaient de (I) caractériser la prévalence et la distribution des activités épileptiques au cours des différents stades du sommeil chez 30 patients atteints de la MA, en comparaison avec une population de contrôles appariés et de (II) comprendre leur impact sur le déclin cognitif et sur la consolidation mnésique. A cette fin ont été réalisés chez les participants, un examen vidéo-EEG avec détection des activités épileptiques et polysomnographie, un examen neuropsychologique, avec des tests de mémoire réalisés à la fois avant et après la nuit de sommeil. Ces mesures ont été complétées par une IRM cérébrale, une analyse génétique (chez les patients), et une évaluation des facteurs liés au mode de vie afin d'évaluer, avec le moins de biais possible, l'impact des activités épileptiques sur la MA. Les résultats préliminaires avec 25 participants par groupe montrent un risque de survenue des activités épileptiques 5 fois plus élevé chez les patients. Contrairement aux souris, les patients présentent des activités épileptiques surtout pendant le sommeil lent, pendant les stades plus profonds. De plus, la proportion de sommeil superficiel chez les patients est augmentée au détriment du sommeil profond, avec des altérations mineures de la microarchitecture du sommeil, notamment une diminution du nombre des fuseaux du sommeil durant le stade N2. Par ailleurs, la prévalence du syndrome d'apnée du sommeil est étonnamment élevée dans notre échantillon : 50% chez les participants contrôles, et encore plus (63%) chez les patients. Bien que la taille de notre échantillon soit actuellement insuffisante pour tirer des conclusions définitives de nos résultats préliminaires, ceux-ci suggèrent un impact composite de la quantité du sommeil, des anomalies respiratoires, des AEs et de la MA elle-même sur les déficits de la consolidation mnésique en particulier en mémoire épisodique. Ainsi, la recherche et le traitement des activités épileptiques et des apnées du sommeil ainsi que l'amélioration de la qualité du sommeil pourrait potentiellement ralentir le déclin des fonctions mnésiques chez les patients atteints de la MA<br>With more than 30 million people diagnosed worldwide, Alzheimer's disease (AD) is the most frequent neurodegenerative disorder. Previous research on murine models of AD highlighted the potential role of cerebral excitatory-inhibitory imbalance in the pathophysiology of AD. Clinical research has since reported that it may give rise to epileptic activities in as much as 50% of AD patients. However, these epileptic events may remain undetected due to their silent, mostly sleep-occurring nature. Therefore, the first part of this project corresponded to a preclinical study in which we aimed at (I) characterizing epileptic activities over the sleep-wake cycle in the Tg2576 mouse model and (II) gaining better insight into the mechanistic underpinnings of these peculiar epileptic events. Tg2576 mice displayed frequent epileptic activities that were predominant during REM sleep and highly locked to the phase of the theta cycle corresponding to the maximal firing probability of pyramidal cells, hinting at a potential deficit of inhibitory activity leading to hyperexcitability - which is coherent with previous results in our laboratory. Secondly, this epileptic activity seems to be prevented during wakefulness - and partially during slow-wave sleep - by noradrenergic signalling via alpha1 adrenoreceptors. In contrast, EA would be unmasked during REM sleep when noradrenergic cells cease firing. Given the early degeneration of the locus coeruleus - the primary source of noradrenaline in the brain - in AD patients, this could also have important clinical implications. In the second part of the project, the objective was to explore the prevalence and the distribution of epileptic activities during sleep in a cohort of 30 AD patients compared to a group of age-matched, healthy controls and to understand the impact of these activities on cognitive decline and sleep-related memory consolidation. To this end, a full-night video-EEG combined with polysomnography was undertaken, together with a two-part neuropsychological test battery with pre-and post-sleep memory tests included. These measures were combined with brain imaging (MRI), genetic analyses (only for AD patients), and the evaluation of lifestyle-related factors to evaluate, with the strict minimum of biasing factors, the impact of epileptic activities on AD progression. Preliminary results with 25 participants per group are reported here. Our results hint at a risk ratio for EA occurrence five times higher in patients than controls. In contrast to our preclinical results, epileptic events are predominant during non-REM sleep and especially during deeper (N2 and N3) stages. We also report increased percentages of superficial sleep in patients at the detriment of deeper ones. Coherently, slight alterations of the sleep-microarchitecture, and namely, of sleep spindle quantities that are otherwise the most pronounced during N2 sleep, are observed in the patient group. Notably, the prevalence of sleep apnoea syndrome is unexpectedly high: whilst still higher in AD patients (63%) than in controls (50%), concerns at least half of the participants in both groups. While our sample size is currently insufficient to draw steady conclusions from our results, our preliminary models suggest a combined impact of sleep quantity, sleep apnoea, epileptic events and AD itself on memory consolidation, especially on episodic memory. We suggest that treating EAs, sleep apnoea and improving sleep quality could potentially slow down or lessen memory complaints in AD patients

Abstract Several anaesthetics are able to induce a burst-suppression (B-S) pattern in the electroencephalogram (EEG) during deep levels of anaesthesia. A burst-suppression pattern consists of alternating high amplitude bursts and periods of suppressed background activity. All monitors measuring the adequacy of anaesthesia recognize the EEG B-S as one criterion. A better understanding of EEG burst-suppression is important in understanding the mechanisms of anaesthesia. The aim of the study was to acquire a more comprehensive understanding of the function of neural pathways during deep anaesthesia. The thesis is comprised of four prospective clinical studies with EEG recordings from 64 patients, and of one experimental study of a porcine model of epilepsy with EEG registrations together with BOLD fMRI during isoflurane anaesthesia (II). In study I, somatosensory cortical evoked responses to median nerve stimulation were studied under sevoflurane anaesthesia at EEG B-S levels. In study III, The EEGs of three Parkinson`s patients were observed to describe the characteristics of B-S during propofol anaesthesia using scalp electrodes and depth electrodes in the subthalamic nucleus. In study IV, EEG topography was observed in 20 healthy children under anaesthesia mask induction with sevoflurane. Twenty male patients were randomized to either controlled hyperventilation or spontaneous breathing groups for anaesthesia mask induction with sevoflurane in study V. EEG alterations in relation to haemodynamic responses were examined in studies IV and V. Somatosensory information reached the cortex even during deep anaesthesia at EEG burst-suppression level. Further processing of these impulses in the cortex was suppressed. The EEG slow wave oscillations were synchronous over the entire cerebral cortex, while spindles and sharp waves were produced by the sensorimotor cortex. The development of focal epileptic activity could be detected as a BOLD signal increase, which preceded the EEG spike activity. The epileptogenic property of sevoflurane used at high concentrations especially during hyperventilation but also during spontaneous breathing together with heart rate increase, was confirmed in healthy children and male. Spike- and polyspike waveforms concentrated in a multifocal manner frontocentrally<br>Tiivistelmä Useat anestesia-aineet pystyvät aiheuttamaan aivosähkökäyrän (EEG) purskevaimentuman syvän anestesian aikana. Purskevaimentuma koostuu EEG:n suuriamplitudisten purskeiden sekä vaimentuneen taustatoiminnan vaihtelusta. Kaikkien anestesian syvyyttä mittaavien valvontalaitteiden toiminta perustuu osaltaan EEG:n purskevaimentuman tunnistamiseen. Tämän ilmiön parempi tunteminen on tärkeää anestesiamekanismien ymmärtämiseksi. Tutkimuksen päämääränä oli saada kattavampi käsitys hermoratojen toiminnasta syvässä anestesiassa. Väitöskirjatyö koostuu neljästä prospektiivisesta yhteensä 64 potilaan EEG-rekisteröinnit sisältävästä tutkimuksesta sekä yhdestä kokeellisen epilepsiatutkimuksen koe-eläintyöstä, jossa porsailla käytettiin isofluraanianestesiassa sekä EEG-rekisteröintejä sekä että magneettikuvantamista (fMRI) samanaikaisesti (II). Ensimmäisessä osatyössä tutkittiin keskihermon stimulaation aiheuttamia somatosensorisia herätepotentiaaleja aivokuorella EEG:n purskevaimentumatasolla sevofluraanianestesian aikana. Kolmannessa osatyössä selvitettiin propofolianestesian aiheuttamaa EEG:n purskevaimentumaa kolmelta Parkinsonin tautia sairastavalta potilaalta käyttäen sekä pintaelektrodien että subtalamisen aivotumakkeen syväelektrodien rekisteröintejä. Neljännessä osatyössä tutkittiin EEG:n topografiaa 20:llä terveeellä lapsella indusoimalla anestesia sevofluraanilla. Kaksikymmentä miespotilasta nukutettiin sevofluraanilla ja heidät satunnaistettiin joko kontrolloidun hyperventilaation tai spontaanin hengityksen ryhmiin osatyössä V. EEG-muutoksia sekä niiden yhteyttä verenkiertovasteisiin selviteltiin molemmissa osatöissä IV ja V. Omasta kehosta tuleviin tuntoärsykkeisiin liittyvä somatosensorinen informaatio saavutti aivokuoren myös syvässä EEG:n purskevaimentumatasoisessa anestesiassa. Impulssien jatkokäsittely aivokuorella oli kuitenkin estynyt. EEG:n hidasaaltotoiminta oli synkronista koko aivokuoren alueella, sen sijaan unisukkulat ja terävät aallot paikantuivat sensorimotoriselle aivokuorelle. Paikallisen epileptisen toiminnan kehittyminen oli mahdollista havaita jo ennen piikikkäiden EEG:n aaltomuotojen ilmaantumista edeltävänä BOLD-ilmiöön liittyvänä aivoverenkierron lisääntymisenä. Sevofluraanin epileptogeenisyys varmistui erityisesti hyperventilaation, mutta myös spontaanin hengityksen yhteydessä ja näihin liittyi sykkeen nousu sekä terveillä lapsilla että miehillä. Piikkejä ja monipiikkejä käsittävien aaltomuotojen keskittymistä esiintyi otsalohkon keskialueilla

En plus des crises, les patients atteints d'épilepsie du lobe temporale (ELT) souffrent de déficits cognitifs tels que des troubles de l'apprentissage et de la mémoire épisodique. La formation de la mémoire épisodique nécessite des interactions entre le cortex et l'hippocampe pendant le sommeil. Ces interactions sont orchestrées par l'oscillation lente qui est générée dans le réseau thalamocortical. L'oscillation lente se propage dans d'autres structures sous corticales mais l'hippocampe semble être moins influencé. Cela pourrait être du à la fonction de filtre du gyrus denté. Dans l'ELT, le gyrus denté subit une réorganisation structurelle et fonctionnelle qui pourrait altérer sa fonction de filtre et aussi modifier la propagation d'activités épileptiformes du cortex vers l'hippocampe. Cependant, la propagation de rythmes physiologiques du cortex vers le réseau hippocampique pendant l'épileptogenèse a été peu étudié. Ce travail de thèse a eu pour but d'étudier l'influence des oscillations lentes corticales sur le potentiel de membrane et la décharge des cellules granulaires du gyrus denté dans un modèle d'ELT sous anesthésie. Nos résultats montrent une augmentation de la modulation du potentiel de membrane et ainsi que de la décharge des cellules granulaires du gyrus par l'oscillation lente corticale pendant l'épileptogenèse. Les changements qui s'opèrent dans le gyrus denté pendant l'épileptogenèse le rendraient plus permissif aux informations en provenance du cortex facilitant ainsi la propagation des oscillations lentes du cortex vers l'hippocampe<br>In addition to seizures, patients with temporal Lobe Epilepsy (TLE) suffer from cognitive deficits such as learning and episodic memory impairment. The functional interactions between the cortex and the hippocampus notably during sleep are thought to be important for episodic memory formation. These interactions are orchestrated by the slow oscillation which is generated in thalamo-cortical networks. The slow oscillation is not confined to thalamo-neocortical networks but propagates to other subcortical structures but the hippocampus seems however less strongly influenced by the widespread propagation of the slow oscillation. This could result from the gate function of the dentate gyrus. In TLE, the dentate gyrus is associated with profound structural and functional network alterations which can alter the propagation of pathological activities such as epileptiform discharges from the cortex to the hippocampus. However, whether and how epilepsy modifies the impact of physiological activities on hippocampal networks remains to be investigated. This work was designed to study the influence of slow cortical oscillations on the membrane potential and discharge of granule cells in the dentate gyrus in an animal model of TLE. Our results show an increase in the modulation of membrane potential and as well as the discharge of granule cells in the dentate gyrus by the cortical slow oscillation during epileptogenesis. The changes that occur in the dentate gyrus during epileptogenesis would make it more permissive facilitating the spread of slow oscillations from the cortex to the hippocampus

Les récepteurs NMDA (NMDARs) sont des canaux cationiques activés par le glutamate. Les NMDARs participent au développement cérébral, à la plasticité synaptique, à l'apprentissage, à la mémoire et aux fonctions cognitives supérieures. Des variants pathogènes de GRIN2A, codant pour la sous-unité GluN2A des NMDARs, peuvent causer des épilepsies focales et encéphalopathies épileptiques de l'enfance avec troubles du langage et de la parole, connue sous le nom de spectre des épilepsies-aphasies (EAS). Les caractéristiques communes de l'EAS comprennent une activité épileptiforme âge-dépendante activée pendant le sommeil lent associées à des troubles de la parole, de la cognition et du comportement qui peuvent persister à l'âge adulte. Afin de commencer à identifier les événements précoces possiblement associés aux altérations de GluN2A, nous avons exploré le modèle correspondant de souris knock-out (KO) du gène Grin2a. Nous avons notamment recherché des altérations précoces de la communication vocale, de la (micro)structure cérébrale, et de l'activité électrique néocorticale. Nos données démontrent l'existence de plusieurs altérations à ces différents niveaux, parfois transitoirement à des stades spécifiques. De plus, les enregistrements néocorticaux mettent en évidence des anomalies de divers types liées au sommeil lent. Nos résultats indiquent également un rôle de GluN2A dans la communication vocale, dans l'organisation de la microstructure cérébrale, et dans la maturation des activités d’ondes lentes. Ces données suggèrent que les souris KO Grin2a représentent un modèle fiable pour appréhender les mécanismes physiopathologiques associés à l’EAS et leur séquence temporelle<br>NMDA receptors (NMDARs) are cation channels that are gated by glutamate - the major excitatory neurotransmitter of the central nervous system. NMDARs participate in brain development, synaptic plasticity, learning, memory and high cognitive functions. Pathogenic variants in the GRIN2A gene, which encodes the GluN2A subunit of the NMDARs, can cause a group of childhood focal epilepsies and epileptic encephalopathies with speech and language dysfunction, known as the epilepsy-aphasia spectrum (EAS). Features shared in common by EAS disorders include age-dependent epileptiform activity activated in sleep associated with speech, neuropsychological and behavioral deficits that may persist in adulthood. In order to start in deciphering the early events possibly associated with the dysfunctioning of GluN2A-containing NMDARs, we have explored the corresponding Grin2a knock-out (KO) mouse model. That consisted in looking for early alterations of vocal communication, of brain (micro)structure, and of neocortical electrical activity. Our data demonstrated the existence of several alterations at those various levels. Some alterations were transient only, being detected at selective stages; also, neocortical recordings pointed for sleep-related anomalies of various types. Our data also indicated a role for GluN2A-containing NMDA receptors in vocal communication, fine organization of brain microstructure, and proper maturation of slow wave activity in sleep. Altogether, our data suggest that the Grin2a KO mice represent a reliable model to further elucidate the pathophysiological mechanisms associated with the disorders of EAS and their temporal sequences

Uzroci gubitka svesti su različiti i te&scaron;ko ih je diferencirati. Razlikovanja epileptičkih od neepileptičkih gubitaka svesti je od krucijalnog značaja za ispitivanje, lečenja i prognoze ovih poremećaja. Elektroencefalografija (EEG) je standardna, neinvazivna metoda koja se koristi u ispitivanju nakon gubitka svesti. Inicijalni EEG nalaz nakon prvog gubitka svesti može biti normalan, specifičan ili nespecifičan. Procenat patolo&scaron;kog EEG nalaza je veći kod rano urađenog EEG pregleda. Kod dece rani EEG pregled u roku od 48h ne pokazuje statistički značajne abnormalnosti. Spontanim spavanjem ili EEG pregledom nakon deprivacije spavanja se beleži značajno veća prisutnost epileptiformnih promena kod dece starije od 3 godine, čak i kada je prvi EEG u budnom stanju normalan. Kombinacijama pregleda u budnom stanju i spavanju povećava prisutnost patolo&scaron;kih promena u EEG zapisu. Materijal metode: Istraživanje je obuhvatilo 198 dece uzrasta od 3-12 godine života nakon prvog gubitka svesti. Ispitanici su klasifikovani u dve grupe na osnovu otpusne dijagnoze: na grupu dece kod kojih dijagnoza epilepsije nije postavljena i na grupu dece kod kojih je dijagnoza epilepsije potvrđena. Korelirani su nalazi EEG-a u budnom stanju i spavanju (spontanom ili nakon deprivacije spavanja) sa anamnestičkim i kliničkim podacima o gubitku svesti, podacima o dužini trajanja gubitka svesti i vremena oporavka, vremenom kada je urađen prvi EEG u odnosu na gubitak svesti kao i sa podacima o ličnoj i porodičnoj anamnezi, a koji su navedeni u protokolu istraživanja. Ispitanici su potom podeljeni prema uzrastu u pet grupa u intervalima od 2 godine (3-4; 5-6; 7-8; 9-10; 11-12). Rezultati: Nakon prvog gubitka svesti specifičan (epileptiformni) nalaz EEG u budnom stanju imalo je 41,97% ispitanika, a 58,03% je imalo nespecifičan ili uredan EEG nalaz u budnom stanju, dok je specifičan nalaz EEG u spavanju imalo je 73,57% ispitanika, a 26,43% je imalo nespecifičan ili uredan EEG nalaz u spavanju. Ispitanici koji su imali specifičan EEG nalaz u budnom stanju imali su i specifičan nalaz u spavanju, a 45,07%, nakon deprivacije sna. Ispitanici koji su u budnom stanju imali nespecifičan ili uredan EEG nalaz u budnom stanju su u 35,92% nakon deprvacije spavanja imali specifičan EEG nalaz u spavanju, za razliku od 1,41% dece koji su imali specifičan EEG nalaz u spontanom spavanju. Sumarno gledano bolesnici koji su &ldquo;aktivirani&rdquo; odnosno oni kod kojih je deprivacija spavanja uticala na dobijanje specifičnog nalaza (epileptiformnih pormena) u spavanju čine 37.32% od svih ispitanika sa specifičnim (epileptiformnim) promenama u EEG-u u spavanju Zaključak: Kod većine pacijenata nakon prvog gubitka svesti EEG nalaz u budnom stanju je bio nespecifičan ili uredan. Procenat specifičnih EEG nalaza (epileptiformnih promena) se značajno povećao prilikom snimanja EEG u spavanju. Naročito velika korist od deprivacije spavanja kao metode aktivacije potvrđena kod onih pacijenata koji su imali inicijalni EEG u budnom stanju uredan ili nespecifičan. Dobijeni rezultati nesumljivo ukazuju na efikasnost deprivacije spavanja kao provokacione metode i povećanja procenta interiktalnihepileptiformnih EEG promena. Neprovociranih prvi gubitci svesti su se če&scaron;će javljali u grupi dece kod kojih je dijagnoza epilepsije potvrđena, dok su se provocirani gubitci svesti javljali če&scaron;će u grupi dece kod kojih dijagnoza epilepsije nije postavljena. Uzrast dece nije uticao na postavljanje dijagnoze epilepsije kao ni na inicijalne nalaze EEGa u budnom stanju i spavanju ali se registrovalo povećanje specifičnih nalaza (epileptiformnih promena) EEG-a, nakon deprivacije spavanja , sa porastom godina života.<br>The reasons for the loss of consciousness are various and difficult to be differentiated. It is of utmost importance to differentiate between epileptic and non-epileptic losses of consciousness for the purpose of testing, treating and giving prognosis related to this disorder. Electroencephalography (EEG) is a standard, non-invasive method used in testing after the loss of consciousness. The initial EEG after the first loss of consciousness can be normal, specific and non-specific. The percentage of pathological EEG findings is higher in EEG exams performed at an earlier stage. In children, an early EEG exam within 48 hours does not reveal any statistically relevant abnormalities. Spontaneous sleeping or an EEG examination after sleep deprivation leads to a significantly higher number of epileptiform changes in children above the age of 3, even in cases when the first EEG in the awake state was normal. Combinations of examinations in the awake state and during sleep lead to an increased presence of pathological changes in the EEG recording. Material and methods: The research included 198 children aged 3-12 who have experienced their first loss of consciousness. The subjects were classified into two groups, based on their discharge diagnosis: children who have not been diagnosed with epilepsy and children who have had epilepsy confirmed. A correlation was established between EEG findings in the awake state and sleep (spontaneous or following sleep deprivation) and medical history and clinical data related to the loss of consciousness, the information about the length of the loss of consciousness and recovery time, the time when the first EEG examination was performed in relation to the loss of consciousness, as well as the data from the personal and family history. The subjects were further divided into five groups, depending on their age, with each group covering a 2-year period (3-4; 5-6; 7-8; 9-10; 11-12). Results: Following the first loss of consciousness, specific (epileptiform) EEG findings were noticed in 41.97% subjects, while 58.03% of them had non-specific, i.e. regular findings in the awake state. When it comes to the findings during sleep, 73,57% were specific, while 26,43% were non-specific, i.e. regular. The subjects who had specific EEG findings in the awake state also had specific findings during sleep, while that percentage was 45,07% after sleep deprivation. The subjects who had non-specific, i.e. regular EEG findings in the awake state had specific EEG findings during sleep in 35.92% of the cases following sleep deprivation, while 1.41% of the children had specific EEG findings during spontaneous sleep. In total, the patients who were &ldquo;activated&rdquo;, i.e. those whose sleep deprivation contributed to specific findings (epileptiform changes) during sleep comprise 37.32% of all subjects with specific (epileptiform) changes in the EEG findings during sleep. Conclusion: In most patients suffering from the first loss of consciousness the EEG findings were non-specific, i.e. regular. The percentage of specific EEG findings (epileptiform changes) was significantly increased when the EEG examination was performed during sleep. Sleep deprivation, as an activation method, was particularly useful in patients whose initial EEG findings in the awake state were regular, i.e. non-specific. The results obtained undoubtedly confirm the efficiency of sleep deprivation as a provoking method and the increase of the percentage of interictal epileptiform EEG changes. Unprovoked first losses of consciousness were more common in the group of children who have had the diagnosis of epilepsy confirmed, while provoked losses of consciousness were more common in the group of children who have not been diagnosed with epilepsy. The age of children did not affect the process of establishing a diagnosis of epilepsy, nor did it affect the initial EEG findings in the awake state or during sleep, but it was observed that the number of specific EEG findings (epileptiform changes) following sleep deprivation increased with the increase of the age of the patients.

Le fonctionnement cérébral est régit par deux grandes forces : un système excitateur, principalement supporté par la transmission gluue,tamatergiq qui s'oppose à un système inhibiteur, principalement supporté par la transmission GABAergique. L'influence mutuelle et équilibrée de ces deux forces est déterminante pour établir et maintenir une activité neuronale physiologique au sein des réseaux neuronaux. Le récepteur métabotropique du glutamate de type 7, mGlu7, est capable de moduler à la fois la transmission glutamatergique et GABAergique, mais sa localisation et son rôle synaptique précis restent largement méconnus à l'heure actuelle. Il semble important pour contrôler le fonctionnement d'une circuiterie particulière supportant notamment la perception sensorielle lors de l'éveil ou la perte de conscience lors de l'endormissement, mais aussi les crises épileptiques d'absence lors d'un dysfonctionnement : le circuit thalamo-cortical. Cette thèse porte sur l'étude des fonctions physiologiques médiées par le récepteur mGlu7a au sein du réseau thalamo-cortical chez la souris. Pour cela, j'ai décortiqué la localisation et les processus électrophysiologiques engendrés par le récepteur dans les synapses thalamiques constituant la circuiterie thalamo-corticale. Le récepteur mGlu7a s'estavéré essentiel dans le contrôle des rythmes oscillatoires au sein du thalamus, associés à la fois au sommeil (les fuseaux de sommeil) et aux épilepsies de type absence.Ce récepteur était présumé ne fonctionner que lors d'activités neuronales intenses. Cette étude complète ce tableau. Elle met en évidence une activité constitutive du récepteur mGlu7a au sein des synapses excitatrices et inhibitrices. Il exerce donc un frein permanent sur l’entrée de Ca2+ dans les présynapses, un acteur crucial pour le développement du système nerveux, la transmission synaptique, l'excitabilité et la plasticité neuronales. Je montre que cette activitémodule la libération de glutamate et de GABA, mais aussi la plasticité à court terme dans certaines synapses du circuit. De plus, le récepteur mGlu7a limite le tonus inhibiteur au sein du thalamus et ainsi l'excitabilité globale thalamique.De façon surprenante pour un récepteur du glutamate, l'ensemble de ces résultats suggère une action physiologique du récepteur mGlu7a particulièrement impliquée dans le contrôle de l'état d'excitabilité des neurones GABAergiques thalamiques et corticaux. En limitant l'apparition d'activités synchrones au sein de la circuiterie, son action abouti in fine au maintien d'un état conscient de l'individu, nécessaire aux traitements des informations sensorielles, mais aussi à l'apprentissage et la mémoire<br>Brain functionning is gouverned by two master forces : excitation, mainly supported by glutamatergic transmission, and inhibition, mainly supported by GABAergic transmission. The mutual and balanced influence of these two forces is instrumental to establish and maintain a physiological neuronal activity, particulary in neuronal networks involving several interconnected brain area and neuron types. The metabotropic glutamate receptor type 7, mGlu7, modulates both glutamatergic and GABAergic transmission, but its precise localization andsynaptic role are still widly unknown. Recently, a genetic mouse model has highlighted mGlu7a receptor's involvement into the functionning of a particular network supporting somatosensory perception during arousal and loss of consciousness during sleep, as well as absence epileptic seizures : the thalamo-cortical network. This thesis aims at understanding physiological functions mediated by the mGlu7a receptor in the thalamo-cortical circuit. I have dissected localization and electrophysiologicalprocesses triggered by the receptor in thalamic synapses. The mGlu7a receptor was proved as essential to control oscillatory rythmes in the thalamus, associated with both sleep-related waves (spindles) and absence epileptic seizures.This receptor was supposed to function only during high neuronal activities. In addition, our study highlights a constitutive activity of mGlu7a receptor in excitatory and inhibitory synapses. It thus exerts a permanent brake on Ca2+ presynaptic entry, which is crucial for neuronal developpement, synaptic transmission, excitability and plasticity. I found that this mechanism modulates glutamate and GABA release, but also short term plasticity in thestudied network. Moreover, mGlu7a receptor slows down the inhibitory tonus in the thalamus and thalamic excitability.Surprisingly for a glutamate receptor, these data suggest that the physiological action of mGlu7a receptor is highly involved in the control of the excitability of inhibitory thalamic and cortical neurons. By decreasing synchronous activities of the network, its action leads in fine to the maintenance of a conscious, awake state of a subject, that is necessary for sensorial informations processing, learning and memory

L'hippocampe peut présenter différents rythmes oscillatoires au cours du cycle veille-sommeil, chacun étant impliqué dans des processus cognitifs. Par exemple, des oscillations thêta-gamma sont produites pendant la veille et sont associés à la navigation spatiale et la mémoire à court terme, tandis que des complexes sharp-wave-ripples, produits durant les périodes de sommeil lent profond, jouent un rôle important dans la consolidation de la mémoire. Des modèles existent pour reproduire chacun de ces rythmes, cependant les mécanismes impliqués dans leur génération et les transitions entre eux ne sont pas encore parfaitement compris. Cette question est d'autant plus importante qu'une altération des rythmes hippocampiques est impliquée dans l'épilepsie du lobe temporal médian phamaco-résistante, une forme courante d'épilepsie qui ne peut pas être contrôlée par les traitements médicamenteux existants. Des modèles ont aussi été développés pour reproduire des crises d'épilepsie ou des pointes intercritiques, mais ces modèles ne parviennent pas à expliquer entièrement les liens entre les conditions neuropathologiques de l'hippocampe, des processus physiologiques comme le cycle veille-sommeil, et les oscillations qui en résultent. Dans ce contexte, l'objectif principal de cette thèse est d'apporter une meilleure compréhension de diverses oscillations hippocampiques, tant physiologiques que pathologiques. Pour ce faire, nous développons tout d'abord un modèle computationnel de l'hippocampe sain incluant au total plus de trente mille neurones Hodgkin-Huxley, représentés par des dizaines de milliers d'équations différentielles résolues numériquement, et comprenant une estimation du potentiel extracellulaire (LFP) généré par les neurones dipolaires tel que mesuré par une électrode macroscopique afin d'être plus facilement interprété. Nous effectuons ensuite une étude complète de l'activité de notre réseau basée sur des plans d'expérience afin d'étudier le rôle des paramètres intrinsèques du modèle et l'importance de la stimulation en entrée dans la production de différents rythmes couplés. Par la suite, notre modèle est évalué dans un contexte réaliste: l'activité qu'il génère quand il est soumis à des entrées réalistes est comparée avec des enregistrements intracérébraux obtenus sur des patients épileptiques. Nous montrons ainsi que notre modèle est capable de générer des oscillations de veille ou de sommeil similaires aux signaux cliniques sur le plan temporel et fréquentiel. Nous relions les modifications de paramètres du modèle (gains synaptiques et conductances de canaux ioniques) à une modulation cholinergique, et montrons comment les dynamiques des neurones influencent principalement les oscillations basse fréquence, tandis que la connectivité fonctionnelle contrôle les oscillations haute fréquence. Enfin, nous détaillons davantage notre modèle afin d'inclure quatre modifications de l'hippocampe observées dans les cas d'épilepsies du lobe temporal médian, à savoir la sclérose hippocampique, le bourgeonnement des fibres moussues, et une altération des dynamiques potassiques et chloriques (qui se traduisent par des modifications de la connectivité du réseau ou des paramètres des neurones individuels), et montrons comment ces mécanismes peuvent interagir avec le cycle veille-sommeil décrit précédemment pour donner lieu à des synchronisations et rythmes pathologiques. En conclusion, nous proposons dans cette thèse un modèle unique de l'hippocampe regroupant divers mécanismes précédemment décrits dans des travaux séparés, et analysons son activité oscillatoire tandis que nous varions différents paramètres représentant les propriétés structurelles et fonctionnelles du réseau, ainsi que des modifications pathologiques observées en épilepsie. Nos résultats apportent un nouvel éclairage sur les mécanismes impliqués dans la génération des oscillations hippocampiques, qui pourraient ouvrir la voie à de futures applications cliniques<br>The hippocampus can exhibit different oscillatory rhythms within the sleep-wake cycle, each of them being involved in cognitive processes. For example, theta-nested gamma oscillations, consisting of the coupling of theta and gamma rhythms, are produced during wakefulness and are associated with spatial navigation and working memory tasks, whereas sharp-wave-ripple complexes, consisting of fast oscillatory events occurring during low frequency waves, are produced during slow-wave sleep and quiet waking and play an important role in memory consolidation. Models exist to reproduce and explain the generation of each of these rhythms, yet the mechanisms involved in their generation and the transitions between them are not yet fully understood. This question is all the more important that altered hippocampal rhythms are involved in drug-resistant mesial temporal lobe epilepsy, a common form of epilepsy which cannot be controlled by existing pharmaceutical treatments. Some models have also been previously developed to reproduce epileptic seizures (episodes of excessive neural activity) or interictal discharges (brief peaks of synchronous activity), but these models cannot fully explain the links between neuropathological conditions of the hippocampus, physiological processes such as the sleep-wake cycle, and the resulting oscillations. In this context, the main objective of this thesis is to provide better understanding of various hippocampal oscillations, both physiological and pathological. To do so, we first design a full computational model of the healthy hippocampal formation including the entorhinal cortex, the dentate gyrus and the CA3 and CA1 regions. This model includes more than thirty thousand Hodgkin-Huxley point neurons, represented by tens of thousands differential equations to be solved numerically, as well as an estimation of the extracellular potentials (LFP) generated by the dipolar neurons as measured by a macroscopic electrode, so as to be more easily interpretable. We perform a thorough study of our model's activity based on design of experiments techniques to identify the role of each of its intrinsic parameters and the importance of input stimulation in the production coupled oscillatory outputs. We then evaluate our model in a realistic context : its activity under realistic input stimulation is compared with intracranial recordings obtained in epileptic patients. We demonstrate that our model is able to reproduce both sleep and wakefulness oscillations with temporal and frequential similarities with the clinically measured signals. We link the modification of some parameters of the model (synaptic gains and ion channel conductances) with cholinergic modulation, and show how single neuron dynamics are mostly responsible for the frequency of slow oscillations of our network, while network functional connectivity controls its fast oscillations. Finally, we detail our model further to include four pathological modifications of the hippocampus seen in mesial temporal lobe epilepsies, that is hippocampal sclerosis, mossy fiber sprouting, and impaired potassium and chloride dynamics in pyramidal neurons (which are modeled by changing the network connectivity or the parameters of individual neuron dynamics), and show how these mechanisms can interact with the previously described sleep-wake cycle and lead to pathological synchrony and rhythms such as seizures, interictal spikes and fast ripples. In conclusion, we propose in this thesis a unique model of the hippocampus regrouping many mechanisms previously described in separate works, and analyze its oscillatory activity as we vary different parameters representing either structural or functional properties of the network, as well as pathological modifications observed in epilepsy. Our results provide new insights into the mechanisms underlying the generation of various hippocampal oscillations, which could open the way to future clinical applications

La maladie d'Alzheimer (MA) est une maladie neurodégénérative induisant des troubles cognitifs, et particulièrement des troubles de la mémoire. L'utilisation des souris modèles de la MA a permis de mettre en évidence des altérations de l'activité des réseaux neuronaux hippocampiques et corticaux qui seraient à l'origine des troubles cognitifs. Ainsi,les patients atteints de la MA et des souris transgéniques modèles de la pathologie ont un dysfonctionnement des interneurones exprimant la parvalbumine (PV), à l'origine de la perturbation des oscillations gamma et des troubles cognitifs. Au cours de cette thèse, nous avons fait l'hypothèse que les souris Tg2576, modèles de la MA, présentent une altération progressive des interneurones PV, et de leur matrice extracellulaire spécifique, les PNN. Cela aurait pour conséquence une altération de l'activité cérébrale (hypersynchronie, perturbation de la puissance des oscillations gamma et de leur couplage avec les oscillations thêta), qui sous-tendrait les troubles cognitifs. Ce travail a permis de montrer que les souris Tg2576 présentent effectivement des perturbations des oscillations gamma au cours d'une tâche cognitive. D'autre part, l'activation spécifique des neurones PV par optogénétique permet la génération d'oscillations gamma chez nos souris anesthésiées. Cependant nous n'avons pas pu combiner cette approche à la réalisation tâche cognitive. Nous avons par ailleurs observé une diminution du nombre de neurones PV hippocampiques et de leur PNN à un âge précoce de la pathologie, qui peut toutefois être restauré par un séjour transitoire dans un environnement enrichi. Enfin nous avons mis en évidence que les souris Tg2576 présentent des activités épileptiformes particulièrement au cours du sommeil paradoxal (SP), ainsi qu'une perturbation des oscillations gamma et de leur couplage avec les oscillations thêta dès l'âge de 1.5 mois pendant le SP. Ainsi, les travaux de cette thèse permettent de mieux caractériser l'impact de la MA sur les neurones PV et sur les phénomènes oscillatoires associés à leur fonction<br>Alzheimer's disease (AD) is a neurodegenerative disorder inducing cognitive dysfunction, in particular memory loss. The use of murine models of AD have highlighted alterations of the neural activity of hippocampal and cortical networks leading to alteration of brain oscillations and spontaneous epileptic activities. Interestingly, it has also been found in AD patients and AD mice that GABAergic interneurons expressing parvalbumin (PV) are dysfunctioning, inducing a decrease in gamma oscillations associated with cognitive deficit. Thus, we hypothesized that Tg2576 mice exhibit progressive alteration of PV interneurons, and their specific extracellular matrix (PNN). These would induce aberrant cerebral activity (hypersynchrony, alteration of gamma oscillations and their association with theta oscillations) sustaining cognitive deficits. This work demonstrates that Tg2576 mice exhibit an alteration of gamma power during a cognitive task. On the other hand, the specific activation of PV neurons allows the generation of gamma oscillation in our anesthetized mice, however we haven't been able to try enhancing gamma during a cognitive task. We have also observed a decrease in the number of hippocampal PV neurons and their PNN at an early age of pathology, which can be restored by a transient stay in an enriched environment. Finally, we demonstrate that Tg2576 mice exhibit epileptiform activities, particularly during paradoxical sleep (PS), as well as an alteration of gamma oscillations and their coupling with theta oscillations during PS, as early as 1.5 months of age. Thus, these results allow to better characterize the impact of AD on PV neurons and the oscillatory phenomena associated with their function

Dissertação de Mestrado Integrado em Engenharia Biomédica apresentada à Faculdade de Ciências e Tecnologia<br>Approximately 30% of epileptic patients are unable to achieve seizure control through antiepileptic drug administration or surgical procedures.Seizure prediction is a promising approach to improve their quality of life due to its applicability in warning or intervention systems.These systems would attempt to prevent the occurrence of seizures or, at least, reduce their side effects.A core aspect for this research field is the identification of the preictal period, which represents the transition from normal brain activity to a seizure.Although this field has been moving forward over the years, current electroencephalogram seizure prediction algorithms fail to attain real-life applicability.Although recent findings show that the circadian cycle holds great interest in seizure dynamics, and that neglecting this information may severely affect the performance of prediction algorithms, few studies have addressed this topic.The present study aimed to ascertain the impact of the incorporation of vigilance states (sleep/wakefulness) in seizure prediction.Considering 33 patients with nocturnal frontal lobe epilepsy from the CAP Sleep database, a subject-independent sleep-awake classifier was developed and achieved satisfactory results (0.94±0.01 for sensitivity and 0.93±0.03 for specificity).According to the vigilance states of 17 drug-resistant epilepsy patients from the EPILEPSIAE database obtained through the sleep-awake model, four different patient-specific seizure prediction approaches were proposed with a 5-minute seizure prediction horizon.The best performing approach considered the transitions between vigilance states in the post-processing phase, which led to results of 0.54±0.36 for sensitivity and of 4.96±11.40 for the false positive rate per hour, with an average seizure occurrence period of 31 minutes.Despite statistically validating 71% of patients, the maximum false positive rate acceptable for each intervention system must be investigated in order to ascertain the applicability of the present study.<br>Aproximadamente 30% dos doentes epilépticos são incapazes de atingir o controlo de crises através da administração de medicamentos antiepilépticos ou de procedimentos cirúrgicos.A previsão de crises é uma abordagem promissora para melhorar a qualidade de vida destes doentes devido à sua aplicabilidade em sistemas de aviso ou de intervenção.Estes sistemas pretendem prevenir a ocorrência de crises ou, pelo menos, reduzir os efeitos colaterais.Um aspeto fucral para este campo de investigação é a identificação do período pré-ictal, que representa a transição de uma atividade cerebral normal para uma crise.Apesar da evolução ao longo dos anos e com base no electroencefalograma, os algoritmos de previsão de crises existentes não conseguem atingir aplicabilidade clínica.Embora negligenciar a informação dos estados dormir/acordado possa afetar negativamente a performance desses algoritmos, e apesar de ser sabido que os ciclos circadianos influenciam significativamente a ocorrência de crises, apenas alguns estudos tiveram em conta este problema.O presente estudo pretende averiguar o impacto da incorporação dos estados de vigilância (dormir/acordado) na previsão de crises.Considerando 33 doentes com epilepsia nocturna do lobo frontal da base de dados CAP Sleep, um classificador de sono foi desenvolvido e atingiu resultados satisfatórios (0.94±0.01 de sensibilidade e 0.93±0.03 de especificidade).Depois, foram testadas quatro abordagens de previsão de crises, nas quais se usaram 17 doentes epilépticos resistentes à medicação. Nestas abordagens foram incorporados os estados de vigilância, obtidos com o classificador anteriormente desenvolvido. Todas as abordagens são especificas para cada doente e têm um horizonte de previsão de crise de 5 minutos. A melhor implementação teve em conta as transições entre os estados de vigilância na fase de pós-processamento, levando a resultados de 0.54±0.36 para a sensibilidade e de 4.96±11.40 para a taxa de falsos positivos por hora, com um tempo médio de 31 minutos para o período de ocorrência da crise.Apesar de ter validado estatisticamente 71% dos doentes, o valor máximo de falsos positivos aceitável para cada sistema de intervenção deve ser investigado de modo a averiguar a aplicabilidade do presente estudo.

碩士<br>國立臺灣大學<br>護理學研究所<br>107<br>Sleep disturbances and lower physical activity levels are common among children with epilepsy. Both sleep and physical activity are closely related to health, and research has found that regular and moderate physical activity can improve the quantity and quality of sleep for children, adolescents, and adults. However, the links between the physical activity levels and sleep patterns of toddlers and preschool-age children with epilepsy are still unclear. For this reason, this study aimed to examine the correlation between physical activity levels and sleep patterns in this population. The amount of light in the nighttime sleep environment was also taken into consideration. The objectives of this study were as follows: (1) describe the daytime physical activity levels and sleep patterns of children with epilepsy between the ages of 18 months and 6 years, (2) analyze the daytime physical activity data obtained from actigraphs worn by children with epilepsy between the ages of 18 months and 6 years, and (3) examine the relationship between the daytime physical activity levels and sleep patterns of children with epilepsy between the ages of 18 months and 6 years. Participants for this cross-section study were recruited at a pediatric neurology clinic of a medical center in northern Taiwan. A total of 98 children with epilepsy wore an actigraph for 7 days, and their parents provided the children’s health information, completed the Children’s Sleep Habits Questionnaire (CSHQ) and a sleep diary. The results showed that the amounts of time spent by children with epilepsy on moderate-to-vigorous physical activities during the day was 0.60±0.82 hours. Among the participants, 51 children (52.0%) had nightlights, and only 23 children (23.5%) had a nighttime sleep efficiency greater than 85%. The overall CSHQ score (56.00±5.69) indicated moderate to severe sleep disturbances. Correlation analyses found that more hours and a higher percentage of time spent on moderate-to-vigorous physical activities were correlated with shorter nighttime sleep duration (rp = -0.23, p < 0.05；rp = -0.21, p < 0.05) and shorter total sleep duration (rp = -0.23, p < 0.05；rp = -0.21, p < 0.05). Correlation analyses also revealed that more daily screen time was correlated with higher daily total physical activity (r = 0.50, p < 0.01), later bedtime at night (r = 0.23, p < 0.05), and later wake-up time in the morning (r = 0.21, p < 0.05). Findings from our study are expected to improve the current understanding of the association between physical activity and sleep patterns in children with epilepsy, and to provide the basis to guide future interventions.

Trabalho Final do Mestrado Integrado em Medicina apresentado à Faculdade de Medicina<br>Introdução: A síndrome de Dravet é uma encefalopatia epilética de origem genética, rara. Mais de 80% dos doentes com Síndrome de Dravet apresentam mutação no gene SCN1A que codifica a Nav 1.1, responsável pelo surgimento de distúrbios do sono devido à desregulação das redes neurológicas. Objetivo: Caracterizar a natureza dos distúrbios do sono em doentes diagnosticados com Síndrome de Dravet.Material e Métodos: Tratou-se de um estudo observacional descritivo e analítico transversal, feito com base numa amostra intencional constituída por cinco doentes, de ambos os sexos e idades entre os cinco e os 14 anos, com critérios clínicos, eletroencefalográficos e genéticos de Síndrome de Dravet. O estudo foi realizado, com a autorização da Comissão de Ética do Centro Hospitalar e Universitário de Coimbra, com recurso a polissonografia (PSG) e aplicação do Children’s Sleep Habits Questionnaire – versão portuguesa (CSHQ-VP).Resultados: A idade média das crianças em estudo foi de 10,8 ± 3,4 anos. A polissonografia mostrou fragmentação do sono, com aumento do índice de microdespertares em quatro dos cinco doentes. Observou-se também alteração da arquitetura do sono em todos os doentes, com aumento do percentual de tempo total de sono em NREM 2 e uma diminuição em NREM 3 quando comparado com os valores normais para a idade. O índice de perturbação do sono calculado a partir da aplicação do CSHQ-VP foi superior ao ponto de corte sugerido para a população portuguesa em todos os doentes. Todos os doentes apresentaram valores superiores à média ± desvio padrão nas subescalas Resistência em ir para a cama e Duração de sono.Discussão: A alteração da arquitetura do sono pode estar associada aos despertares corticais ou subcorticais resultantes das crises epiléticas/descargas epiletiformes características desta síndrome ou associada a perturbações respiratórias do sono. O aumento da fragmentação do sono, por seu turno, é um achado bastante específico em doentes com Síndrome de Dravet.Conclusão: O estudo do sono mostra uma alteração da arquitetura e hábitos do sono, com consequente impacto na qualidade de vida nos doentes com Síndrome de Dravet.<br>Introduction: Dravet Syndrome is a rare epileptic encephalopathy of genetic origin. Over 80% of the patients with Dravet Syndrome have a mutation in the SCN1A gene which encodes Nav 1.1, responsible for the appearance of sleep disorders due to the dysregulation of neurological networks.Objective: To characterize the nature of sleep disorders in patients diagnosed with Dravet Syndrome.Material and Methods: This was a descriptive observational and analytical cross-sectional study, based on an intentional sample consisting of five patients, from both genders, between the ages of five and 14 years old, who met the clinical, electroencephalographic, and genetic criteria of Dravet Syndrome. The study was carried out with authorization from the Ethics Committee of the Centro Hospitalar e Universitário de Coimbra, resorting to polysomnography (PSG) and the application of the Children’s Sleep Habits Questionnaire - Portuguese version (CSHQ-VP).Results: The average age of the children in the study was 10.8 ± 3.4 years. The polysomnography showed sleep fragmentation, with an increase in the microarousal index in four of the five patients. A change in sleep architecture it was also observed in all patients, with a percentage increase in total sleep time in NREM 2 and a decrease in NREM 3, when compared to the age-related reference values. The sleep disturbance index calculated by applying the CSHQ-VP was higher than the cutoff score suggested for the Portuguese population in all patients. All patients presented values above the mean ± standard derivation in the subscales Bedtime Resistance and Sleep Duration.Discussion: The change in sleep architecture may be associated with cortical or subcortical arousal resulting from epileptic seizures/epileptiform discharges, which is characteristic of this syndrome or associated with respiratory sleep disturbances. The increase in sleep fragmentation, in turn, is a very specific finding noted in patients with Dravet Syndrome.Conclusion: The sleep study shows a change in sleep architecture and habits, with a consequent impact on quality of life in patients with Dravet Syndrome.

碩士<br>高雄醫學大學<br>醫學系神經學科碩士班<br>96<br>Backgroung: Epilepsy is a chronic neurological disorder caused by abnormal and repetitive electric firing of brain cells. Sleep disturbance (including poor sleep quality, excessive daytime sleepiness and sleep apnea etc.) is common in patients with epilepsy. It could affect their working ability. social activity and quality of life. It may also worsen the course of the disease by increasing the frequency of attack, aggravating cognitive disability and behavior problems. However, there was only a few publications in the literature about it. The influencing factors on the health-related quality of life include frequency of epilepsy, type of epilepsy, side effect of anticonvulsants, change of sleep architecture, and related sleep disorders. Recent studies regarding the quality of sleep and health-related quality of life in patient with epilepsy are inconclusive. It is probably related to the cross-culture difference and different sampling method. The goal of this study was to investigate the difference of sleep quality, excessive daytime sleepiness and health-related quality of life between medically refractory and nonrefractory epilepsy and their correlation. Method: Eighty-eight patients with epilepsy ( 32 refractory and 56 nonrefractory epilepsy patients) were recruited by purposive sampling. The demographic data including sex, age and clinical manifestations including the duration of epilepsy, type of seizure, frequency of seizure within half year, cause of the epilepsy, comorbidity, the anticonvulsant within two months and neuroimage study were collected. After obtaining the informed consent, the patients completed the Pittsburgh sleep quality index (PSQI), the Epworth sleepiness scale (ESS) and the short form-36 survey (SF-36). All patients received electrocephalography (EEG or video EEG monitoring). Twenty five of them also agreed to receive polysomnography (PSG). Forty-six patients with primary insomnia were also recruited for comparison. Result: There was no significant difference on sleep quality and excessive daytime sleepiness between the patients with medically refractory epilepsy (PMRE) and the patients with medically nonrefractory epilepsy (PMNE), but PMRE had relatively poorer sleep quality and more excessive daytime sleepiness than PMNE. In health-related quality of life, PMRE had significantly lower score on social functioning (p<0.001), role limitation due to emotional problems (p=0.016) and mental component summary (MCS) (p=0.019) than PMNE. There was significant correlation between sleep quality and health-related quality of life, especially on the mental health component in PMNE. After adjusting the confounding factors, age (p<0.001), sleep quality (p<0.001) and excessive daytime sleepiness (p=0.017) were independently associated with mental health of health-related quality of life and age (p<0.001) was the only independent factor associated with physical health of health-relted quality of life. In comparison with patients with primary insomnia (PPI), in general the PPI had significantly poorer sleep quality and poorer health-related quality of life than PMRE and PMNE. The PSG study revealed that PMRE had shorter REM sleep than PMNE (P=0.031). Conclusion: In general, PMRE have poorer mental health of health-related quality of life than PMNE. Sleep quality was significantly correlated with the mental component of health-related quality of life, especially in PMNE. The age, sleep quality and excessive daytime sleep were the major influcing factors on mental component of health-related quality of life. The influencing factors on quality of life in patients with epilepsy were different in different publications. The possible reasons were the individual variation ( such as type of seizure, frequency of seizure, age of onset and anticonvulsant) and the corss-cultural difference (such as family support and religious belief) in epilepsy. A large-scaled study should be conducted to clarify these findings.

碩士<br>高雄醫學大學<br>醫學系神經學科碩士班<br>99<br>The interrelationship is complex between sleep and epilepsy. Sleep deprivation can precipitate epileptic seizures. And epileptiform discharges are more frequently detected in sleep than in awake. However, epileptic discharges occur rarely during REM sleep and REM sleep was ever stated to have some “protective effect” for epilepsy. Although more and more new anti-epileptic drugs are available, 30% of epilepsy patients still do not have satisfied seizure control, and some of them suffer from drug-resistant or medically intractable epilepsy. We tried to study REM sleep in epilepsy patients in both medically intractable and non-intractable groups. We collected 48 epilepsy patients, 28 of them were non-intractable patients and 20 of them were medically intractable patients. They received overnight polysomnography study and wrote a series of questionnaires about sleep quality, life quality, and daytime sleepiness. We analyzed both macrostructure and microstructure of REM sleep. We found that there was significantly lower percentage of REM sleep in medically intractable epilepsy patients. In power spectrum of EEG during REM sleep, there is significantly decreased beta and alpha relative power and increased delta relative power in medically intractable epilepsy patients. In simultaneous heart rate variability analysis, there seems no significant difference exist between these two groups. So we emphasize the important role of REM sleep in medically intractable epilepsy. We also try to clarify those complexed interrelationships between sleep and epilepsy, at least to some degree.

Brain signal analysis has a crucial role in the investigation of the neuronal activity for diagnosis of brain diseases and disorders. The electroencephalogram (EEG) is the most efficient biomarker for the analysis of brain signal that assists in the diagnosis of brain disorder medication and also plays an essential role in all the neurosurgery related to the brain. EEG findings illustrate the meticulous condition, and clinical content of the brain dysfunctions, and has an undisputed importance role in the detection of epilepsy condition and sleep disorders and dysfunctions allied to alcohol. The clinicians visually study the EEG recording to determine the manifestation of abnormalities in the brain. The visual EEG assessment is tiresome, fallible, and also high-priced. In this dissertation, a number of frameworks have been developed for the analysis and classification of EEG signals by addressing three different domains named: Epilepsy, Sleep staging, and Alcohol Use Disorder. Epilepsy is a non-contagious chronic disease of the brain that affects around 65 million people worldwide. The sudden onset tendency of the epileptic attacks vulnerable their sufferers to injuries. It is also challenging for the clinical staff to detect the epileptic-seizure activity early enough for determining the semiology associated with the seizure onset. For that reason, automated techniques that can accurately detect the epilepsy from EEG are of great importance to epileptic patients and especially to those patients who are resistive to therapies and medications. In this dissertation, four different techniques (named Weighted Visibility Network, Weighted Horizontal Visibility Network, Weighted Complex Network, and New Weighted Complex Network) have been developed for the automated identification of epileptic activity from the EEG signals. Most of the developed schemes attained 100% classification outcomes in their experimental evaluation for the identification of seizure activity from non-seizure activity. A sleep disorder can increase the menace of seizure incidence or severity, cognitive tasks impairments, mood deviation, diminution in the functionality of the immune system and other brain anomalies such as insomnia, sleep apnoea, etc. Hence, sleep staging is essential to discriminate among distinct sleep stages for the diagnosis of sleep and its disorders. EEG provides vital and inimitable information regarding the sleeping brain. The study of EEG has documented deformities in sleep patterns. This research has developed an innovative graph- theory based framework named weighted visibility network for sleep staging from EEG signals. The developed framework in this thesis, outperforms with 97.93% overall classification accuracy for categorizing distinct sleep states Alcoholism causes memory issues as well as motor skill defects by affecting the different portions of the brain. Excessive use of alcohol can cause sudden cardiac death and cardiomyopathy. Also, alcohol use disorder leads to respiratory infections, Vision impairment, liver damage, and cancer, etc. Research study demonstrates the use of EEG for diagnosis the patient with a high menace of developmental impediments with alcohol. In this current Ph.D. project, I developed a weighted graph-based technique that analyses EEG to distinguish between alcoholic subject and non-alcoholic person. The promising classification outcome demonstrates the effectiveness of the proposed technique.