To see the other types of publications on this topic, follow the link: Prefrontal Cortex.
Dissertations / Theses on the topic 'Prefrontal Cortex'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Prefrontal Cortex.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Vander, Weele Caitlin Miya. "Dopaminergic modulation of prefrontal cortex subpopulations." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120628.
Full textAbstract:
Thesis: Ph. D. in Neuroscience, Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, 2018.Cataloged from PDF version of thesis. Page 176 blank.
Includes bibliographical references (pages 159-175).
Despite abundant evidence that dopamine modulates medial prefrontal cortex (mPFC) activity to mediate diverse behavioral functions, the precise circuit computations remain elusive. One potentially unifying theoretical model by which dopamine can modulate functions from working memory to schizophrenia is that dopamine serves to increase the signal-to-noise ratio in mPFC neurons, where neuronal activity conveying sensory information (signal) are amplified relative to spontaneous firing (noise). To connect theory to biology, we lack direct evidence for dopaminergic modulation of signal-to-noise in neuronal firing patterns in vivo and a mechanistic explanation of how such computations would be transmitted downstream to instruct specific behavioral functions. Here, we demonstrate that dopamine increases signal-to-noise ratio in mPFC neurons projecting to the dorsal periaqueductal gray (dPAG) during the processing of an aversive stimulus. First, using electrochemical approaches, we reveal the precise time course of tail pinch-evoked dopamine release in the mPFC. Second, we show that dopamine signaling in the mPFC biases behavioral responses to punishment-predictive stimuli, rather than reward-predictive cues. Third, in contrast to the well-characterized mPFC-NAc projection, we show that activation of mPFC-dPAG neurons is sufficient to drive place avoidance and defensive behaviors. Fourth, to determine the natural dynamics of individual mPFC neurons, we performed single-cell projection-defined microendoscopic calcium imaging to reveal a robust preferential excitation of mPFC-dPAG, but not mPFC-NAc, neurons to aversive stimuli. Finally, photostimulation of VTA dopamine terminals in the mPFC revealed an increase in signal-to-noise ratio in mPFC-dPAG neuronal activity during the processing of aversive, but not rewarding stimuli. Together, these data unveil the utility of dopamine in the mPFC to effectively filter sensory information in a valence-specific manner.
by Caitlin Miya Vander Weele.
Ph. D. in Neuroscience
2
Benoit, R. G. "Functional specialisation within rostral prefrontal cortex." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/623668/.
Full textAbstract:
The functional organisation of rostral prefrontal cortex (rPFC; approximating Area 10) is largely unknown. On one hand, this region might support processes that are commonly involved in coping with multiple demands. On the other hand, rPFC might be fractionated into functionally specialised subregions. This thesis examines which of these accounts is more plausible. Therefore, four functional MRI studies were conducted, each of which compared two functions. These were hypothesised to share common processing denominators that might be supported by medial rPFC (mrPFC). It was assessed whether the functions are associated with haemodynamic signal changes in overlapping versus segregated subregions. Study I investigated the involvement of rPFC in prospective memory and in stimulus-oriented (i.e. triggered by the environment) versus stimulus-independent (i.e. decoupled from the environment) processing. Study II asked participants to envision future episodes of spending money (e.g., £35 at a Pub). It was hypothesised that subregions supporting such episodic prospection might also exhibit haemodynamic signal changes as a function of the imagined reward value (e.g., £35). In study III, participants first made personality trait judgements about themselves and others (i.e., their best friends), and then tried to remember the target of each judgement. It was investigated whether mrPFC subregions involved in thinking about oneself during those tasks might also support thinking about others to the degree that the other person is perceived as similar. Study IV examined the relationship between mrPFC engagement during self-appraisal and individual differences in the valuation of future rewards. Overall, the data are most consistent with a synthesis of the two accounts: mrPFC seems to be functionally fractionated. However, the specialised subregions appear to be engaged irrespective of the exact task context (e.g., the nature of the stimuli). Thus, these regions may be characterised as supporting central functions that are involved in coping with multiple demands.
3
Pereira, Jacinto José Fonseca. "Computational modeling of prefrontal cortex circuits." Doctoral thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica, 2014. http://hdl.handle.net/10362/12080.
Full textAbstract:
Dissertation presented to obtain the Ph.D degree in BiologyThe most outstanding feature of the human brain is its ability to perform highly complex cognitive tasks and one key region of the brain involved in these elaborated tasks is the prefrontal cortex. However, little is known about the basic neuronal processes that sustain these capacities. This dissertation describes the computational study of the biophysical properties of neurons in the prefrontal cortex that underlie complex cognitive processes with special emphasis in working memory, the ability to keep information online in the brain for a short period of time while processing incoming external stimuli.(...)
4
Cholfin, Jeremy A. "Genetic regulation of prefrontal cortex development." Diss., Search in ProQuest Dissertations & Theses. UC Only, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3251942.
Full text
5
Fernandes, Ninette M. "The Detection of Prefrontal Cortex Development into Early Adulthood." Marietta College / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=marietta1164924291.
Full text
6
Bedwell, S. A. "The connectivity of the mammalian prefrontal cortex." Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/28042/.
Full textAbstract:
The fine scale connections of prefrontal cortex (PFC) were investigated in the rat brain, in order to determine organizational properties of PFC pathways which were previously undefined. Neuroanatomical tract tracers (Fluro-Gold, Fluoro-Ruby, Fluoro-Emerald, Biotinylated dextran amines; Fluorescein and Texas red) were injected (20 -100 nl) into subdivisions of PFC (prelimbic, infralimbic, medial-orbital, ventral-orbital, ventrolateral-orbital, lateral-orbital and dorsolateral-orbital) and their projections studied. Tracer studies identified clear evidence of significantly ordered projections from PFC to temporal and sensory-motor cortices in three axes of orientation (p<0.001), showing differential ordering of input and output connections (p<0.001). Ordered connections were consistent across PFC (from anterior to posterior) and showed evidence of changes in organisation in anterior compared to posterior PFC, in both the PFC-temporal and PFC-sensory-motor cortex pathways. Detailed analysis revealed evidence for an organizational gradient in the relationship between inputs and outputs from anterior to posterior PFC, in which retrograde and anterograde labelling become increasingly differentiated as PFC injection site is moved from posterior to anterior. Analysis of fine scale tracer injections (20-30 nl) revealed evidence to show underlying complex organizational properties of connections from PFC to temporal and sensory-motor cortices. Taken together, the findings show that PFC displays ordered arrangements of connections to temporal and sensory-motor cortex, input and output connections are consistently not found in the same locations and the relationship between inputs and outputs differs in relation to the anterior-posterior location in PFC.
7
Sandblom, Johan. "Episodic memory in the human prefrontal cortex /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-136-4/.
Full text
8
Duffaud, Anais M. "Executive function and prefrontal cortex in rats." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54745/.
Full textAbstract:
The term executive function describes a set of high-level abilities that influence more basic motor, sensory and mnemonic processes. These functions include working memory, behavioural flexibility, inhibitory control, attentional processes and decision making. A large number of evidence, from human studies, non-human primates, rats and mice studies, has demonstrated a role for the prefrontal cortex in these higher cognitive processes. The central aim of this thesis was to investigate two important aspects of the cognitive executive control: working memory and behavioural flexibility. The experiments described in the first two empirical chapters present the design of new operant paradigms to study these processes. Two further empirical chapters consider the neurobiological basis of behavioural flexibility, with a particular emphasize on the infralimbic (IL) and prelimbic (PL) regions of the rat medial prefrontal cortex (mPFC). Although, the IL and PL regions have generally been considered as a single functional unit, empirical findings presented in this thesis provide evidence suggesting that the IL and PL mPFC can be viewed as independent but interactive regions with complementary roles in the control of behaviour. That is, the PL brings simple cue-outcome associations and more complex behavioural patterns under the modulatory influence of contextual, or other task-relevant, information and in contrast, the IL exerts an inhibitory influence over the PL biasing the animal towards simple, prepotent, learned or innate behavioural patterns.
9
Cox, Simon Riddington. "Cortisol, cognition and the ageing prefrontal cortex." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/9585.
Full textAbstract:
The structural and functional decline of the ageing human brain varies by brain region, cognitive function and individual. The underlying biological mechanisms are poorly understood. One potentially important mechanism is exposure to glucocorticoids (GCs; cortisol in humans); GC production is increasingly varied with age in humans, and chronic exposure to high levels is hypothesised to result in cognitive decline via cerebral remodelling. However, studies of GC exposure in humans are scarce and methodological differences confound cross-study comparison. Furthermore, there has been little focus on the effects of GCs on the frontal lobes and key white matter tracts in the ageing brain. This thesis therefore examines relationships among cortisol levels, structural brain measures and cognitive performance in 90 healthy, elderly community-dwelling males from the Lothian Birth Cohort 1936. Salivary cortisol samples characterised diurnal (morning and evening) and reactive profiles (before and after a cognitive test battery). Structural variables comprised Diffusion Tensor Imaging measures of major brain tracts and a novel manual parcellation method for the frontal lobes. The latter was based on a systematic review of current manual methods in the context of putative function and cytoarchitecture. Manual frontal lobe brain parcellation conferred greater spatial and volumetric accuracy when compared to both single- and multi-atlas parcellation at the lobar level. Cognitive ability was assessed via tests of general cognitive ability, and neuropsychological tests thought to show differential sensitivity to the integrity of frontal lobe sub-regions. The majority of, but not all frontal lobe test scores shared considerable overlap with general cognitive ability, and cognitive scores correlated most consistently with the volumes of the anterior cingulate. This is discussed in light of the diverse connective profile of the cingulate and a need to integrate information over more diffuse cognitive networks according to proposed de-differentiation or compensation in ageing. Individuals with higher morning, evening or pre-test cortisol levels showed consistently negative relationships with specific regional volumes and tract integrity. Participants whose cortisol levels increased between the start and end of cognitive testing showed selectively larger regional volumes and lower tract diffusivity (correlation magnitudes <.44). The significant relationships between cortisol levels and cognition indicated that flatter diurnal slopes or higher pre-test levels related to poorer test performance. In contrast, higher levels in the morning generally correlated with better scores (correlation magnitudes <.25). Interpretation of all findings was moderated by sensitivity to type I error, given the large number of comparisons conducted. Though there were limited candidates for mediation analysis, cortisol-function relationships were partially mediated by tract integrity (but not sub-regional frontal volumes) for memory and post-error slowing. This thesis offers a novel perspective on the complex interplay among glucocorticoids, cognition and the structure of the ageing brain. The findings suggest some role for cortisol exposure in determining age-related decline in complex cognition, mediated via brain structure.
10
Dumontheil, Iroise. "Cortex prefrontal rostral et contrôle de l'attention." Paris 6, 2006. http://www.theses.fr/2006PA066505.
Full textAbstract:
Le cortex préfrontal rostral est une aire cérébrale plus étendue chez les humains que les autres primates et qui se développe tardivement jusqu’à l’adolescence. Trois expériences ont testés la Gateway hypothesis, qui propose que l’aire 10 soutient des processus de coordination de l’attention entre les informations dérivées de l’environnement (orientées vers le stimulus, SO), et les informations générées intérieurement (indépendantes du stimulus, SI). Une dissociation de fonction entre la partie médiale, associée à une amélioration de la performance dans des tâches d’attention SO et les parties latérales, associées à une allocation de l’attention vers les représentations SI, a été montrée par deux expériences d’imagerie par résonance magnétique fonctionnelle. De plus, il a été démontré que les processus de l’aire 10 latérale pouvaient être recrutés dans des tâches de faible demande cognitive. Ces résultats permettent de mieux spécifier les fonctions possibles de l’aire 10.
11
Aly, Mahmoud Mayada. "Role of prefrontal cortex dopamine in associative learning." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0185.
Full textAbstract:
La dopamine du cortex préfrontal (PFC) est impliquée dans l’apprentissage et dans la prise de décision liée à l’effort. Comme l’apprentissage ne peut se faire sans effort, il n’est pas clair aujourd’hui si la dopamine est nécessaire pour l’apprentissage, ou pour l’engagement de l’effort pour apprendre. Dans ce travail, les rats apprenaient à pousser un levier pour obtenir de la nourriture, soit avec (apprentissage par observation, LeO) ou sans (essai-et-erreur, TE) observation préalable d’un congénère exécutant la tâche. TE et la phase d’exécution de LeO nécessitent l’effort physique (overt learning), l’observation dans LeO ne requiert pas d’effort physique (covert learning). Avant chaque session, les rats recevaient des injections de SCH23390 ou de la saline dans le cingulaire antérieur (ACC) ou l’orbitofrontal (OFC). Si la dopamine est nécessaire à l’apprentissage, le blocage des récepteurs D1 affecterait aussi bien l’apprentissage overt que covert. Si la dopamine n’est pas requise pour l’apprentissage mais pour l’engagement de l’effort, le blocage affecterait l’apprentissage overt, et non covert. Les résultats montrent que le blocage de la dopamine dans ACC ou OFC supprime l’apprentissage overt, laissant intact l’apprentissage covert. Une fois les injections arrêtées, les rats récupèrent la capacité d’apprendre, mais dans le cas de ACC, pas la tolérance à l’effort. Ces résultats suggèrent que la dopamine dans ACC et OFC n’est pas nécessaire pour l’apprentissage, et que les déficits d’apprentissage pourraient reflèter une réduction de la tolérance effort à l’effort liée au blocage de la dopamineBecause prefrontal cortex (PFC) dopamine plays a pivotal role in associative learning and in effort-related decision making, it is not clear as of today whether PFC dopamine activity is required for learning per se, or rather for engaging the effort necessary to learn. In this work, we used observational learning (LeO) and trial-and-error (TE) learning to dissociate learning from physical effort. Both TE and the execution phase of LeO require physical effort (overt learning). Observation does not require physical effort (covert learning). Rats learned to push a lever for food rewards either with or without prior observation of an expert conspecific performing the same task. Before daily testing sessions, the rats received bilateral ACC or OFC microinfusions of SCH23390, or saline-control infusions. If dopamine activity is required for task acquisition, its blockade should impair both overt and covert learning. If dopamine is not required for task acquisition, but solely for regulating effort tolerance, blockade should impair overt learning but spare covert learning. We found that dopamine blockade in ACC or OFC suppressed overt learning selectively, leaving covert learning intact. In subsequent testing sessions without dopamine blockade, rats recovered their overt-learning capacity but, in ACC experiments, the animals did not recover their normal level of effort tolerance. These results suggest that ACC and OFC dopamine is not required for the acquisition of conditioned behaviours and that apparent learning impairments could instead reflect a reduced level of effort tolerance due to cortical dopamine blockade
12
Hardung, Stefanie [Verfasser], and Ilka [Akademischer Betreuer] Diester. "Contributions of prefrontal cortex subsections to response inhibition." Freiburg : Universität, 2018. http://d-nb.info/1161670459/34.
Full text
13
Johnson, Shane Douglas. "Memory monitoring abilities, prefrontal cortex functioning and ageing." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368628.
Full text
14
Warden, Melissa R. (Melissa Rhoads). "Multi-item memory in the primate prefrontal cortex." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35910.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The ability to retain multiple items in short-term memory is fundamental for cognition, yet almost nothing is known about its neural basis. To explore the mechanisms underlying this ability, we trained two monkeys to remember a sequence of two images across a short delay. We then recorded the activity of neurons from the lateral prefrontal cortex during task performance. We found that the majority of neurons showed delay activity that depended on the identity of both images (a minority reflected just one image), and that activity related to a given combination of images was only partially predictable from each neuron's activity to individual images. A model to predict the resultant neural activity was tested. We also examined the effect of task demands on the neural representation of multiple images. Our first experiment showed that each of the two images in memory was represented with a certain strength, and that this strength was dependent on how long the image had been in memory; image strength decayed as time progressed.
(cont.) We found that changing the way that the memory of the images was reported, from a bar release to a sequence of eye movements, changed the relative strength of the image representations. In the eye-movement version of the task the strength of the representation of the image did not decay with time; in fact the strength of older images could even surpass the strength of newer images, depending on how frequently the tasks were switched. Further experiments showed that when the monkey switched between the two tasks individual neurons could turn their image coding on and off. We also found a substantial population of cells that directly represented the task that the animal was performing.
by Melissa R. Warden.
Ph.D.
15
Esmaeili, Vahid. "Neuronal correlates of tactile working memory in rat barrel cortex and prefrontal cortex." Doctoral thesis, SISSA, 2014. http://hdl.handle.net/20.500.11767/3869.
Full textAbstract:
The neuronal mechanisms of parametric working memory – the short-term storage of graded stimuli to guide behavior – are not fully elucidated. We have designed a working memory task where rats compare two sequential vibrations, S1 and S2, delivered to their whiskers (Fassihi et al, 2014). Vibrations are a series of velocities sampled from a zero-mean normal distribution. Rats must judge which stimulus had greater velocity standard deviation, σ (e.g. σ1 > σ2 turn left, σ1 < σ2 turn right). A critical operation in this task is to hold S1 information in working memory for subsequent comparison. In an earlier work we uncovered this cognitive capacity in rats (Fassihi et al, 2014), an ability previously ascribed only to primates. Where in the brain is such a memory kept and what is the nature of its representation?
To address these questions, we performed simultaneous multi-electrode recordings from barrel cortex – the entryway of whisker sensory information into neocortex – and prelimbic area of medial prefrontal cortex (mPFC) which is involved in higher order cognitive functioning in rodents. During the presentation of S1 and S2, a majority of neurons in barrel cortex encoded the ongoing stimulus by monotonically modulating their firing rate as a function of σ; i.e. 42% increased and 11% decreased their firing rate for progressively larger σ values. During the 2 second delay interval between the two stimuli, neuronal populations in barrel cortex kept a graded representation of S1 in their firing rate; 30% at early delay and 15% at the end. In mPFC, neurons expressed divers coding characteristics yet more than one-fourth of them varied their discharge rate according to the ongoing stimulus. Interestingly, a similar proportion carried the stimulus signal up to early parts of delay period. A smaller but considerable proportion (10%) kept the memory until the end of delay interval.
We implemented novel information theoretic measures to quantify the stimulus and decision signals in neuronal responses in different stages of the task. By these measures, a decision signal was present in barrel cortex neurons during the S2 period and during the post stimulus delay, when the animal needed to postpone its action. Medial PFC units also represented animal choice, but later in the trial in comparison to barrel cortex. Decision signals started to build up in this area after the termination of S2.
We implemented a regularized linear discriminant algorithm (RDA) to decode stimulus and decision signals in the population activity of barrel cortex and mPFC neurons. The RDA outperformed individual clusters and the standard linear discriminant analysis (LDA). The stimulus and animal’s decision could be extracted from population activity simply by linearly weighting the responses of neuronal clusters. The population signal was present even in epochs of trial where no single cluster was informative.
We predicted that coherent oscillations between brain areas might optimize the flow of information within the networks engaged by this task. Therefore, we quantified the phase synchronization of local field potentials in barrel cortex and mPFC. The two signals were coherent at theta range during S1 and S2 and, interestingly, prior to S1. We interpret the pre-stimulus coherence as reflecting top-down preparatory and expectation mechanisms.
We showed, for the first time to our knowledge, the neuronal correlates of parametric working memory in rodents. The existence of both positive and negative codes in barrel cortex, besides the representation of stimulus memory and decision signals suggests that multiple functions might be folded into single modules. The mPFC also appears to be part of parametric working memory and decision making network in rats.
16
Greenberg, Paul Arthur. "Functional Stability and Learning in the Dorsolateral Prefrontal Cortex." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1030%5F1%5Fm.pdf&type=application/pdf.
Full text
17
Fox, Geoffrey Arthur. "Effects of aging on functions of the prefrontal cortex." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050112.155754/index.html.
Full text
18
Ding, Ding Col Dau. "The medial prefrontal cortex to nucleus accumbens projection neurones." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393479.
Full text
19
Thompson, Russell John. "The representation of behavioural relevance in human prefrontal cortex." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613358.
Full text
20
Sluming, Vanessa Anne. "Structure and function of prefrontal cortex in professional musicians." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250356.
Full text
21
Rainer, Gregor 1970. "Processing of relevant information in the primate prefrontal cortex." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/16733.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 1999.Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Extracellular recordings of neural activity were made in areas around and ventral to the principal sulcus of the lateral prefrontal (PF) cortex in two monkeys (macacca mulatta). Activity was assessed during the performance of three visual memory tasks. In the first task, the sensory and mnemonic receptive fields were studied, by requiring monkeys to simultaneously remember both the identity and the location of an object presented at different locations. We report that many conveyed both object and spatial information during the sensory and mnemonic period. Receptive field size was similar during the two periods (10.8 deg. during sensory, 9.3 deg. during mnemonic period). In addition, visual space contralateral to the recording site was preferentially represented. In a second task, the effect of attention on the responses of PF neurons was studied. Visual scenes were presented which contained three objects, only one of which was relevant for behavior. We report that PF neural activity selectively represented information about this relevant object, and activity was often identical to when the relevant object was presented alone. In addition, we describe the time-course of this attentional effect, and show that the relevant object captures PF activity very early, as soon as 140msec after onset of the visual scene. In a third task, the role of PF neurons in a visual-visual association task was assessed. Monkeys were presented with sample objects, and had to choose the test objects that had been associated with them during training after a short delay. The behavior of the monkeys suggested that they were using a prospective strategy to solve this task, i.e. they were recalling the associated visual information soon after sample presentation, and maintaining this in working memory. We report that many neurons showed activity consistent with prospective coding. Examination of the time course of this effect suggests that the recall took place several 100 msec after sample presentation, and that the strongest prospective effects appeared 300-500msec before test object presentation. In conclusion, across these three tasks PF neural activity selectively represented information relevant to immediate behavioral demands.
by Gregor Rainer.
Ph.D.
22
Ahmad, Asma. "The role of the prefrontal cortex in pain modulation." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:d959eb19-c859-48a4-9a29-2f120d6f629f.
Full textAbstract:
Existing knowledge identifies the prefrontal cortex (PFC) as the modulatory area for pain. Previous neuroimaging studies suggest the existence of the cortico-cortical pathway, an alternative pain modulatory pathway distinct from the descending modulatory pathway of pain. However, little is known of the extent, mechanism and underlying substrate of the modulation. The objective of this study is therefore to explore the role of the PFC in pain modulation. To examine the extent of PFC involvement in pain, meta-analyses of imaging studies in healthy volunteers and patients with chronic pain were performed. Using Gaussian-process regression (GPR) analysis, brain maps were produced from foci of activation as reported in the studies. Since structure dictates function, our next study was to performprobabilistic tractography on diffusion-weighted brain images to ascertain the connection probability of lateral PFC subdivisions and pain-related brain regions as well as intrinsic PFC connections. Two behavioural studies were conducted to investigate cognitive modulation of pain. The first was a study to assess the subjective and physiological correlates of cognitive stress, as previously used in stress-induced analgesia studies. The second was to investigate the involvement of the endogenous opioid system inthe cognitive modulation of pain through effortful reappraisal and contextual modulation. Meta-analyses in healthy volunteers and chronic pain patients revealed activation mainly in the lateral aspect of the PFC due to pain. Distinct pattern of activation was demonstrated in patients with significant ventrolateral PFC (VLPFC) activation across subtypes of chronic pain. Probabilistic tractography further illustrate the functional significance of lateral PFC subdivisions by demonstrating differential connection probability to pain-related brain regions; dorsolateral PFC (DLPFC) regions displayed higher connection probability with brain regions serving more sensory-discriminative function while VLPFC showed high connection probability with both sensory-discriminative and affective regions. Behavioural study of stress showed that cognitive stress failed to induce significant increases in biomarkers of stress, and was not affected by increased level of difficulty. Lastly, behavioural study on contextual modulation and reappraisal confirmed opioid mediation for contextual modulation while negating its involvement in effortful reappraisal. Findings from this studyillustrate the extent of PFC involvement in pain modulation especially in chronic pain patients and provide further evidence of an alternative pathway distinct from the opioid-mediated descending inhibitory pathway.
23
Neubert, Franz-Xaver. "Ventral prefrontal cortex structure and function in behavioural change." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:1723e174-d0a5-462d-a096-02e6ff7cca5b.
Full textAbstract:
There is a considerable interest in the neural correlates of cognitive flexibility, language, valuation, credit assignment and decision-making. The ventrolateral, orbital and medial prefrontal cortex together with their long-range connections with the rest of the brain are thought to be critically involved in these cognitive processes. My thesis explores human and monkey ventrolateral, orbital and medial prefrontal cortex and their potential role in flexible adaptation and choice. In the introductory chapter I review neuroeconomic and neuro-ecological views of decision making, as well as modular versus connectionist views of brain structure and function. In the second and third chapter I investigate the connectivity of ventrolateral, orbital and medial prefrontal cortex and compare their sub-regions between humans and monkeys. Overall I report a striking degree of similarity of connectivity profiles across species even though these regions are thought to support uniquely human cognitive abilities such as language, social cognition, prospective planning and strategic decision-making. This may be taken to suggest that higher order cognitive functions 're-use' a neural apparatus that is shared with macaque monkeys. In the fourth chapter I present a parcellation of the white matter into the major long-range association fibre systems based on their projection patterns to the cortical surface. These findings may have implications not only for the cross-species comparison of connectivity-profiles but also for understanding some psychiatric and neurological disorders as "disconnection syndromes". I conclude by evaluating whether a modular view of brain structure and function is consistent with a view that portraits the brain as changeable, highly adaptive and strongly interconnected.
24
Malalasekera, W. M. N. "Neuronal mechanisms of decision making in the prefrontal cortex." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1474040/.
Full textAbstract:
This thesis examines several aspects of decision computations which are critical for understanding the processes by which decisions are made. It will show that subjects engaged covert attention to bias both saccadic and choice processes during simple decision making tasks even when these stimuli were novel. This saccadic behaviour was overridden when one presented stimulus is relatively more novel than the other implying the existence of separate value comparison circuits in the brain which deal with making value based decisions about attention and choice respectively. Even when the task was made more complex by introducing multiple decision variables this phenomenon of covert attention was maintained. This thesis will demonstrate that subjects controlled both the amount and manner of information gathering during decisions. This behaviour showed features of a confirmation bias. Single cell neuronal recordings were performed while subjects executed a multiattribute decision making task. ACC neurons represented action values and different populations of OFC neurons encoded attribute and attentional values. These neurons did not just reflect value (i.e. an input into a decision process) but instead evolved their coding to represent final choice thereby implying the existence of a parallel decision making circuit which compares value in different frames of reference. Information gathering strategy was also computed in the same frames of reference implying the existence of a common value comparison system which simultaneously drives both choice and information gathering. At the outcome of the decision ACC neurons encoded both categorical reward outcome and positive prediction errors. vmPFC neurons encoded prediction errors while OFC and ACC neurons encode fictive value when rewards were withheld. Finally frame of reference specific computations were observed in LPFC and OFC. The results in this thesis therefore provide novel insight into the role of valuation circuitry during value based decision making and outcome monitoring.
25
Lanoue, Amelie Cecile. "Neuropathology in the dorsolateral prefrontal cortex in Parkinson's disease." Thesis, Boston University, 2013. https://hdl.handle.net/2144/11112.
Full textAbstract:
Thesis (Ph.D.)--Boston UniversityDegeneration of dopaminergic neurons in the substantia nigra pars compacta is the hallmark neuropathological feature of Parkinson's disease (PD). Multiple lines of evidence from anatomical and imaging studies indicate that cell loss or cell dysfunction also occur in other brain regions. The dorsolateral prefrontal cortex (DLPFC) is a region of interest because it could be implicated in both cognitive and motor symptoms of PD. However, studies in this brain region are limited and the extent of pathology is unclear. Work in this thesis was aimed at identifying possible neuropathology in post-mortem PD tissue from Brodmann area 9 (BA9), a region of the DLPFC. In the first study, using design-based stereology and radioisotopic in situ hybridization histochemistry (ISHH), we found that expression of two mitochondrial genes, NDUFS1 and COX1, was not altered and that no global loss of neurons occurs in BA9 in PD. In a second study, using ISHH and gene expression microarray analysis (One-Color Agilent 60-mer Whole Human Genome Microarray), we found decreased gene expression of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD67) in BA9 in PD, an effect that was not paralleled by a decrease in the numbers of GAD67 mRNA-expressing neurons. In a third study, using ISHH, we found that gene expression of the calcium-binding protein parvalbumin, which is selectively expressed in a subset of cortical GABAergic interneurons, is decreased in BA9 in PD. However, we found no loss of immunolabeled parvalbumin-positive neurons in BA9 in PD. In summary, the results indicate that expression of two key markers of GABAergic activity, GAD67 and parvalbumin, is depressed in BA9 in PD and that these effects are not due to a loss of neurons. This suggests that GABAergic neurotransmission is deficient in the DLPFC in PD and we propose that treatments aimed at restoring GABAergic inhibition in BA9 would have therapeutic efficacy in the symptomatic treatment of PD.
26
Basso, Demis. "Involvement of the prefrontal cortex in visuo-spatial planning." Doctoral thesis, La Sapienza, 2005. http://hdl.handle.net/11573/917230.
Full text
27
Kostopoulos, Penelope. "The role of the mid-ventrolateral prefrontal cortex in memory retrieval /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115891.
Full textAbstract:
Although a plethora of data exists on the role of the prefrontal cortex in memory retrieval, it has been difficult to relate specific aspects of retrieval processing to the different prefrontal regions. The present thesis consists of one behavioural experiment and three functional neuroimaging studies that aimed at elucidating the role of the mid-ventrolateral region of the prefrontal cortex in memory retrieval. We hypothesized that the mid-ventrolateral prefrontal cortex, through its anatomical connections with posterior association areas, is in a key position to exert control over posterior association areas where information is processed and stored for the active retrieval of mnemonic information. In contrast to automatic retrieval, active retrieval is necessary when a person retrieves based on his/her plans and intentions a specific memory amongst multiple related mnemonic traces.Previously, we had demonstrated that the mid-ventrolateral prefrontal cortex in the right hemisphere controls active retrieval of non-verbal stimuli. More specifically, we reported activity increases within this region during the delay period that followed the presentation of a retrieval cue. We proposed that these activity increases reflect the top-down control exerted by the mid-ventrolateral prefrontal cortex to focus attention on relevant aspects of encoded memories in preparation for the decision. The first study of my thesis focuses on the behavioural correlates of this active retrieval process. The results indicate that the subjects' performance improves (i.e. becomes faster) with longer retrieval periods. Thus, some aspect of retrieval is initiated during the delay before the presentation of a test stimulus for the decision. The results, however, also indicate that retrieval continues after the presentation of the test stimulus.
The three event-related fMRI studies that make up chapters three, four, and five of the thesis were designed on the basis of the results obtained in the behavioural study described in chapter two. For all three fMRI studies, we used an experimental paradigm in which the retrieval cue coincided with the test stimulus presentation. The experimental design for the three neuroimaging studies was similar but examined the retrieval of mnemonic information from different sensory modalities. A separate group of subjects was tested for each study with a common hypothesis: when subjects are performing active retrieval trials, selective activity increases will be observed within the mid-ventrolateral prefrontal cortex. The study presented in chapter three examined verbal active retrieval, the study presented in chapter four examined tactile active retrieval, and the one in chapter five examined active retrieval for auditory stimuli. Selective activity increases were reported within the mid-ventrolateral prefrontal cortex during the active retrieval trials in all three studies. Activity increases were stronger in the left mid-ventrolateral prefrontal cortex when subjects retrieved verbal information. For tactile and auditory stimuli, the activity increases were bilateral. Importantly, within the prefrontal cortex, there were no other activity increases, indicating that the role of the mid-ventrolateral prefrontal cortex in memory retrieval is specific and distinct from that of other prefrontal regions. Thus it can be concluded that, across sensory modalities, the mid-ventrolateral prefrontal cortex plays a key role in the top-down control necessary for the disambiguation of information in memory during retrieval.
28
Reid, Alastair Gilmour. "Schizophrenia, dopamine, and the prefrontal cortex : theory and computational models." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/26869.
Full textAbstract:
I have suggested a possible mechanism for the action of DA in the PfCx and illustrated this with biologically plausible models which can be interpreted at cellular and pharmacological levels. I have then related this to schizophrenia. Dysfunctions between brain regions are also suggested to underly the symptoms of schizophrenia. This is the other theme of the thesis, where I have used a reinforcement learning based model to examine interactions between brain regions and the effects of variations in DA transmission on these interactions. More specifically, I will show how oscillations between pyramidal cells and GABA cells in the PfCx may arise (chapter 4), and how disruption of this information processing capacity can occur through multiple different pathologies. The existence of oscillations is shown through simulations and theoretically by modelling neurotransmitter interactions within the mesocortical and mesolimbic dopamine (DA) systems (chapter 5). This work reveals the conditions under which oscillations will occur, and shows how DA can act as a control parameter in initiating oscillations. Finally, I have modelled a high level cognitive process, the Tower of London task, using a rule-based model to represent PfCx function and a reinforcement learning model to represent NAcc function (chapter 6). The interaction between the two models is investigated and illustrations of the possible origins of the positive symptoms of schizophrenia are given. In all of these models, the role of DA has been crucial. One conclusion from this work is that the symptoms of schizophrenia may arise through inappropriate fluctuations in DA levels in the NAcc and the PfCx. The work is based on a large amount of neurobiological data and follows theories presented by Friston (1998) and Goldman-Rakic amongst others.
29
Hardwick, Claire Louise. "Neuroanatomical studies of chandelier neurons in rat medial prefrontal cortex." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434850.
Full text
30
Dias, R. "Functional organisation of the prefrontal cortex of the common marmoset." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598525.
Full textAbstract:
In the past, two main theories of prefrontal function in animals have been proposed. The first implicates the prefrontal cortex in working memory, the second in the inhibitory control of behaviour. However, to date the organisation of the prefrontal cortex in the control of these functions is largely unknown. To address the issue of functional organisation within the prefrontal cortex of the marmoset, this thesis focused on the inhibitory control of behaviour. The initial study demonstrated that attentional set-shifting and visual discrimination reversal learning are sensitive to global prefrontal damage in the marmoset in a qualitatively similar manner to that observed previously in man and Old World monkeys respectively. The deficit was interpreted to be one of inhibitory control but, given the cognitive processing demands of these two tasks are different from one another, it is highly probable that the type of inhibitory control required is also different. Subsequently, the effects of discrete lesions specific to either the lateral or orbital regions of the prefrontal cortex on performance of attentional set-shifting and discrimination reversal learning were examined. Whereas the lateral, but not the orbital, prefrontal cortex was the critical locus in shifting an attentional set between perceptual dimensions; in contrast, the orbital, but not the lateral, prefrontal cortex was the critical locus in reversing a stimulus-reward association within a particular perceptual dimension. Both deficits were interpreted as constituting disinhibition or loss of inhibitory control, but a different levels. The inhibitory control required in attentional set-shifting appears to be at the level of attentional selection whereas the inhibitory control required in reversal learning is likely to be at the level of stimulus-reward associations or 'affective' processing.
31
Dissanayake, Watuthanthrige Dilshani Nadira. "Sensory gating in the hippocampus and the medial prefrontal cortex." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/29088/.
Full textAbstract:
Sensory gating is a mechanism by which irrelevant sensory information is filtered in the brain, enabling efficient information processing. The auditory conditioning-test paradigm, an index of sensory gating, measures the reduction in the auditory-evoked response (AER) produced by a test stimulus following an initial conditioning stimulus. Schizophrenic patients demonstrate a lack of attenuation of the test response measured in the P50 component of the cortical auditory-evoked potential. The N2/N40 auditory-evoked potential recorded from rat hippocampus is considered homologous to the human P50 wave. Altered glutamatergic neurotransmission and the endocannabinoid system have been implicated in the pathogenesis of schizophrenia with structural and functional abnormalities in the hippocampus and the medial prefrontal cortex (mPFC). The current study examined sensory gating using auditory conditioning-test paradigm in the dentate gyrus (DG) and the CA3 region of the hippocampus and in the medial prefrontal cortex (mPFC) before and after administration of N-Methyl- D-Aspartate (NMDA) receptor antagonist phencyclidine (PCP; 1 mg/kg, i.p) or the cannabinoid agonist WIN55,212-2 (1.2mg/kg, i.p). Electrophysiological recordings were conducted in Lister hooded rats, under isoflurane anaesthesia, during the presentation of paired auditory stimuli. Extracellular action potential spikes and local field potentials (LFPs) were recorded simultaneously using multi-electrode arrays and the effects of acute administration of PCP (1 mg/kg, i.p) or WIN55,212-2 (1.2mg/kg, i.p) was determined. Gating of the N2 wave was assessed by measuring the ratio of the Test to Conditioning response amplitude (T/C ratio); T/C ratio ≤ 50% was indicative of gating. Robust auditory-evoked potentials were recorded from the hippocampal CA3 and DG regions and the mPFC; some rats demonstrated auditory gating while others failed to. In rats that demonstrated gating of N2, mPFC showed higher T/C ratios and shorter conditioning response latencies compared to DG and CA3. PCP disrupted auditory gating in all three areas with a significant increase in test response amplitudes in the gating rats. PCP had no effect on T/C ratios in the non-gating rats. The atypical antipsychotic clozapine (5mg/kg, i.p) prevented PCP induced disruption of gating in the CA3, DG and mPFC. WIN55,212-2 disrupted auditory gating with a significant increase in test response amplitudes in the gating rats. WIN55,212-2 had no effect on T/C ratios in the non-gating rats. The cannabinoid receptor (CB1) antagonist SR141716A (1mg/kg, i.p) prevented WIN55,212-2 induced disruption of gating. Neither clozapine nor SR141716A had any effects on the non-gating rats. Both PCP and WIN55,212- 2 disrupted gating of the single-unit responses in the CA3, DG and mPFC, effects which were prevented by the pre- administration of clozapine or SR141716A. The non-gating rats may model some inhibitory deficits observed in schizophrenic patients. Administration of PCP disrupted auditory gating which was prevented by clozapine; similar deficits are observed in schizophrenic patients. Furthermore, cannabinoid receptor activation disrupted auditory gating which was prevented by CB1 receptor antagonism, suggesting the endocannabinoid system as a potential target for future clinical research in the treatment in schizophrenia.
32
Gillougley, Claire. "Fast network oscillations in the rodent prefrontal cortex in vitro." Thesis, University of Newcastle upon Tyne, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658036.
Full textAbstract:
Fast network oscillations (~15-80 Hz) in the prefrontal cortex (PFC) have been shown to be essential in a number of important cognitive functions including; memory, attention, learning and emotion. Disruption to these network oscillations have been shown to be apparent in a number of psychiatric pisorders including schizophrenia. The presence of oscillations in the PFC in vivo is extensive, however the mechanisms and pharmacology underlying fast network oscillations in the PFC in vitro remains elusive. The aims of this thesis were to establish mechanisms of generating in vitro fast network oscillations in the rat subdivisions of the mPFe, and to investigate the pharmacological mechanisms underlying this activity. Persistent fast network (gamma and betall) frequency oscillations were evoked by three distinct methods in the rat anterior cingulate (AC) and infralimbic (IL) cortices. Persistent fast network activity could be evoked by concomitant application of the oscillogenic compounds carbachol/kainate (ChlKA) at the concentrations 10 )!M and 200nM respectively, or by application of kainate (KA) alone at the concentration of 800 nM. Transient fast network activity was also evoked in the rat AC and IL cortices by the focal application of NMDA [20 mM], which produced fast network oscillatory activity < 1 minute.
33
Carli, Mirjana. "Serotonergic modulation of attentional processes in the rat prefrontal cortex." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424622.
Full text
34
Passetti, Filippo. "Attentional functions of the rat prefrontal cortex and its neuromodulation." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620322.
Full text
35
Mears, Ryan Phillip. "NEUROPHYSIOLOGY OF AUDITORY INHIBITORY GATING IN RAT MEDIAL PREFRONTAL CORTEX." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1151343744.
Full text
36
Zimmerman, Molly E. "NEUROCOGNITIVE CORRELATES OF PREFRONTAL CORTEX SUBREGION VOLUMES IN BIPOLAR DISORDER." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin989580315.
Full text
37
Bianchin, Marta. "From emotion to decision: role played by the prefrontal cortex." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425573.
Full textAbstract:
The aim of the present work was to investigate role of OFC in startle modulation and emotion processing, and to clarify emotion influence on decision making. Moreover, we were interested in risk anticipation process, that is an important cognitive/emotional component of decision making, and how personality trait influence risky choices and economic decisions. The present studies highlighted that pOFC lesions cause specific deficit on unpleasant stimuli processing. This could be at the basis of participants "myopia" for negative feedback (such as monetary losses), which caused the inability of patients with OFC lesion to adjust their behavior through the retrieval of appropriate emotional events (such as punishments). This inability is typically associated with a tendency to impulsive behavior and inefficient planning. Moreover studies on decision making highlighted the key role of emotion in taking economic and risky decision, both in feedback processing (economic outcomes) and in retrieval processes of stored information. Data about personality trait showed that interindividual differences, in trait anxiety and sensation seeking, are very important in planning and decision of everyday life.
38
Worley, Nicholas B. "Prefrontal Circuit Selection in Stress and Resilience:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108656.
Full textAbstract:
Thesis advisor: John P. ChristiansonStress is a risk factor for neuropsychiatric disorders such as post-traumatic stress disorder and depression, yet not all individuals who are exposed to stress develop such disorders. Several factors influence susceptibility versus resilience to the effects of stress, including coping strategy biological sex. A growing body of research in humans has demonstrated that active coping strategies – defined as using available resources to problem solve – are positively correlated with resilience. In rodents, resilience to a potent acute stressor can be achieved through active coping, such as controlling the termination of a stressor, but only in males. During controllable stress males engage a stress mitigating pathway between the prelimbic (PL) and dorsal raphe nucleus (DRN), but this pathway isn’t engaged by control in females or when stress is uncontrollable in both sexes. Thus, neural activity within the ventromedial prefrontal cortex (vmPFC) is a critical determinant of stressor-induced anxiety. The mechanism that engage vmPFC excitability are not well understood. Therefore, the goals of the dissertation were 1) determine if eCBs in the PL promote neuronal excitability and behavioral resilience 2) test if ES and IS result in differential activation PL afferents, and will specifically test if ES results in greater activation PL-inputs from action-outcome associated regions, while IS leads to greater engagement of stress/fear inputs to the PL, and 3) identify network-wide patterns of activation and test the hypothesis that the stress and action-outcome networks are differentially activated as a function of stressor controllability and/or sex. We’ve demonstrated that augmenting eCBs in the PL increased excitability through a CB1 and GABA receptor dependent mechanism and was sufficient to block the stress induced decrease in social exploration. Regarding goal 2, PL inputs from the orbitofrontal cortex and DRN were activated in response to stress per se, but were not sensitive to stressor controllability and did not differ between males and females. PL afferents from the basolateral amygdala and mediodorsally thalamus were not sensitive to stress. Lastly, we quantified Fos expression in response to controllable and uncontrollable stress in male and female rats in 24 brain regions associated with stress, action-outcome learning, and showing sex differences in response to stress. Using interregional correlations, we found differences in functional connectivity as a function of stressor controllability and sex when considering all 24 regions and when considering only stress associated regions. Females showed greater overall functional connectivity compared with males, and IS resulted in greater overall connectivity than ES. We also reveal potentially important nodes in functional connectivity networks using centrality measures to identify network hubs. The findings of this research emphasize the need to study differences between males and females across all realms of neuroscience, particularly in relation to disorders of stress and anxiety
Thesis (PhD) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Psychology
39
Keifer, Ekaterina. "Performance of patients with ventromedial prefrontal, dorsolateral prefrontal, and non-frontal lesions on the Delis-Kaplan Executive Function System." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/830.
Full textAbstract:
Executive functioning is a multidimensional concept encompassing higher-order adaptive abilities, such as judgment, decision-making, self-monitoring, planning, and emotional regulation. Disruption in executive functioning often results in devastating impairments in vitally-important areas of life, such as one's ability to hold employment and maintain social relationships.
Executive functions have been associated primarily with the prefrontal cortex. However, the nature and degree of the association between frontal lobe damage and performance on executive functioning tests remains controversial. Research suggests that the association may vary based on the specific location of damage within the prefrontal cortex, as well as the used measure of executive functioning. Few investigations have systematically addressed these variables. The current study employed the lesion method to investigate the relationship between performance on a battery of executive functioning tests and damage to specific regions of the prefrontal cortex. Three groups of participants with lesions in one of the locations of interest [ventromedial prefrontal (VMPC, n = 14), dorsolateral prefrontal (DLPC, n = 14), and non-frontal (n = 18)] were administered the Delis-Kaplan Executive Function System (D-KEFS, 2001), a comprehensive battery of executive functioning tests. Results revealed no statistically-significant differences between group performances on the D-KEFS primary measures. However, a qualitative analysis of the results revealed several meaningful group differences. It appears that some relationship exists between frontal lobe damage, particularly in the DLPC, and decreased performance on several executive functioning tests but further research overcoming the methodological limitations of most existing literature on this topic is needed to clearly resolve this issue.
40
Konradsson, Åsa. "Modulation of prefrontal glutamatergic transmission and "atypicality" of antipsychotic drugs /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-344-3/.
Full text
41
Khoder, Suzana. "Role of the prefrontal-brainstem pathway in mediating avoidance behavior." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0256.
Full textAbstract:
Les mammifères, comme par exemple les rongeurs, soumis à des expériences aversives présentent des réponses comportementales de peur caractéristiques notamment une réponse d'immobilisation (freezing) ou d'évitement. Alors que le rôle du cortex préfrontal dorso-médian (CPFdm) dans l’acquisition ainsi que l’expression du freezing a déjà été expérimentalement établi, son implication dans l’encodage des réponses d’évitement de peur ainsi que l’interaction entre les circuits neuronaux préfrontaux impliqués dans le freezing et/ou l’évitement restent mal compris. Afin de répondre à ces questions, nous avons développé au laboratoire un paradigme expérimental permettant à une souris d’acquérir et d’exprimer le freezing ou l’évitement lors de la présentation d'un même stimulus aversif et ceci en fonction du contexte environnant. Ainsi, nous avons pu déterminer si les mêmes circuits neuronaux dans le cortex préfrontal dorso-médian encodent les deux réponses de peur, le freezing et l’évitement. Nous avons mis en oeuvre au cours de ce travail des approches comportementales, de traçage neuroanatomique, d'immunohistochimie, d'enregistrements extracellulaires in vivo et intracellulaires in vitro ainsi que des approches optogénétiques. Nos résultats indiquent que (i) le CPFdm et les régions dorsales de la substance grise périaqueducale sont activés pendant le comportement d'évitement, (ii) une sous population de neurones du CPFdm encode le comportement d'évitement mais pas le freezing, (iii) cette population neuronale projette sur le dl/lPAG, (iv) l'activation et l'inhibition optogénétique de cette projection induit et bloque l'apprentissage de l'évitement, respectivement et (v) l'apprentissage de l'évitement est associé à la mise en place d'une plasticité des afférences préfrontales sur le dl/lPAG. Dans leur ensemble ces résultats démontrent pour la première fois que la plasticité dépendante de l'activité des neurones du CPFdm projettant sur le dl/lPAG contrôle l'apprentissage de l'évitement de peurMammals, including rodents show a broad range of defensive behaviors as a mean of coping with threatful stimuli including freezing and avoidance behaviors. Several studies emphasized the role of the dorsal medial prefrontal cortex (dmPFC) in encoding the acquisition as well as the expression of freezing behavior. However the role of this structure in processing avoidance behavior and the contribution of distinct prefrontal circuits to both freezing and avoidance responses are largely unknown. To further investigate the role of dmPFC circuits in encoding passive and active fear-coping strategies, we developed in the laboratory a novel behavioral paradigm in which a mouse has the possibility to either passively freeze to an aversive stimulus or to actively avoid it as a function of contextual contingencies. Using this behavioral paradigm we investigated whether the same circuits mediate freezing and avoidance behaviors or if distinct neuronal circuits are involved. To address this question, we used a combination of behavioral, neuronal tracing, immunochemistry, single unit and patch clamp recordings and optogenetic approaches. Our results indicate that (i) dmPFC and dorsolateral and lateral periaqueductal grey (dl/lPAG) sub-regions are activated during avoidance behavior, (ii) a subpopulation of dmPFC neurons encode avoidance but not freezing behavior, (iii) this neuronal population project to the dl/lPAG, (iv) the optogenetic activation or inhibition of this pathway promoted and blocked the acquisition of conditioned avoidance and (v) avoidance learning was associated with the development of plasticity at dmPFC to dl/lPAG synapses. Together, these data demonstrate for the first time that activity-dependent plasticity in a subpopulation of dmPFC cells projecting to the dl/lPAG pathway controls avoidance learning
42
Chavez, Candice Monique. "Top-down modulation by medial prefrontal cortex of basal forebrain activation of auditory cortex during learning." CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/3053.
Full textAbstract:
The experiment tested the hypothesis that the acetylcholine (ACh) release in the rat auditory cortex is greater in rats undergoing auditory classical conditioning compared to rats in a truly random control paradigm where no associative learning takes place and that this is mediated by prefrontal afferent projections influencing the nucleus basalis magnocellularis (NBM), which in turn modulates ACh release in neocortex. Rats with bilateral ibotenic acid lesions of medial prefrontal and agranular insular cortices were tested in an auditory classical conditioning task while ACh was collected from the primary auditory cortex. It was hypothesized that lesions of these prefrontal areas would prevent learning-related increases of ACh release in the primary auditory cortex. The hypothesized results were supported. Results from this experiment provide unique evidence that medial prefrontal cortex projections to the NBM are important for mediating cortical ACh release during associative learning.
43
Farooqui, Ausaf Ahmed. "Fronto-parietal cortex in sequential behaviour." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243944.
Full textAbstract:
This dissertation investigates the fronto-parietal representation of the structure of organised mental episodes by studying its effect on the representation of cognitive events occurring at various positions within it. The experiments in chapter 2 look at the completion of hierarchically organized mental (task/subtask) episodes. Multiple identical target-detection events were organized into a sequential task episode, and the individual events were connected in a means-to-end relationship. It is shown that events that are conceptualized as completing defined task episodes elicit greater activity compared to identical events lying within the episode; the magnitude of the end of episode activity depended on the hierarchical abstraction of the episode. In chapter 3, the effect of ordinal position of the cognitive events, making up the task episode, on their representation is investigated in the context of a biphasic task episode. The design further manipulated the cognitive load of the two phases independently. This allowed for a direct comparison of the effect of phase vis-à-vis the effect of cognitive load. The results showed that fronto-parietal regions that increased their activity in response to cognitive load, also increased their activity for the later phases of the task episode, even though the cognitive load associated with the later phase was, arguably, lower than the previous phase. Chapter 4 investigates if the characteristics of the higher-level representations, like organization of task descriptions, have a causal role in determining the structure of the ensuing mental episode. Results show this to be true. They also confirm the results of earlier chapters in a different framework. Chapter 5 shows that the effect of episode structure is not limited to the elicited activity, but also affects the information content of the representation of the events composing the episode. Specifically, the information content in many regions of later steps is higher than that of earlier steps. Together, the results show widespread representation of the structure of organised mental episodes.
44
Darling, Ryan Daniel. "HIPPOCAMPAL THETA-TRIGGERED CONDITIONING: ENHANCED RESPONSES IN HIPPOCAMPUS AND PREFRONTAL CORTEX." Connect to this document online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1130446123.
Full textAbstract:
Thesis (M.A.)--Miami University, Dept. of Psychology, 2005.Title from first page of PDF document. Document formatted into pages; contains [1], v, 48 p. : ill. Includes bibliographical references (p. 16-20).
45
Rubinow, Katya. "Differential Endogenous Estrogen Exposure Influences Prefrontal Cortex Response to Acute Stress." Yale University, 2006. http://ymtdl.med.yale.edu/theses/available/etd-06282006-142135/.
Full textAbstract:
The present study was conducted to determine the effect of differential endogenous estrogen exposure in rats on stress-induced changes in spatial working memory. Subjects comprised male (n=8) and female (n=10) Sprague-Dawley rats, which were trained to complete a T maze, delayed alternation task. Performance was scored as a percentage of trials during which the correct maze arm was selected. Subjects scores were recorded after 1 and 2 hours of restraint stress, as well as after 1 hour of unimpeded movement in a cage placed in the testing room. Restraint stress was effected through physical confinement within plastic, cylindrical tubing. Female subjects underwent each of the testing conditions twice, during periods of high and low endogenous estrogen exposure, as ascertained by microscopic examination of vaginal epithelial cells for estrous cycle stage determination. Females in proestrus (elevated endogenous estrogen exposure) subjected to 1 hour of restraint performed significantly worse than their baseline scores (p=0.0017) or females in estrus (low endogenous estrogen exposure) after 1 hour of restraint (p=0.00014). After 1 hour of restraint, females in proestrus also committed an increased rate of perseverative errors compared to females in estrus, although this increase did not achieve statistical significance (p=0.06). No appreciable differences existed among subject groups in baseline performance or subsequent to 2 hours of restraint stress. Resultant data indicate impaired working memory among female rats under conditions of stress in the context of elevated endogenous estrogen exposure. This study, then, suggests a potential synergistic effect of stress and estrogen in compromising prefrontal cortex function and, therefore, may lend insight into the observed sex-related disparity in the incidence of major depressive disorder and other anxiety-related mood disorders.
46
Cullen, Thomas. "The neuropathology of the prefrontal cortex and mediodorsal thalamus in schizophrenia." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427875.
Full text
47
Cruse, Damian. "Event-related potential studies of prefrontal cortex contributions to episodic retrieval." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54347/.
Full textAbstract:
Although the prefrontal cortex (PFC) is known to play roles in episodic memory retrieval, the specific processes it supports are not fully understood. The high temporal resolution of the event-related potential (ERP) technique provides one fruitful avenue for investigations of these processes. However, the PFC-supported retrieval operations that may be indexed by ERPs are currently under-specified. The work contained in this thesis is concerned with providing a more specific characterisation of PFC-supported processes that operate during episodic retrieval than is available currently. To this end, Experiments One to Three were designed in order to assess the likely functional significance of one known modulation which has been identified in ERP studies of episodic retrieval - the right-frontal ERP old/new effect. This effect is widely assumed to reflect activity generated within the PFC. Experiments Four and Five extended this work to related issues which arose as a result of the outcomes of the initial experiments. All five experiments reported in this thesis employed source memory tasks in which participants studied a list of words presented in one of two contexts (or sources). These words were presented visually in one of two colours in Experiments One, Two, Three, and Five (Visual condition), and were presented auditorily in a male/female voice in Experiments Four and Five (Auditory condition). At test, in all experiments, all studied words were presented visually in white letters intermixed with unstudied (new) words. For words judged to have been encountered previously (old words), a second judgment was required. In Experiments One and Two, this was a binary decision regarding the source in which the word had been previously presented (study colour). In Experiments Three, Four, and Five, a high/low source confidence rating was also made. For the right-frontal ERP old/new effect, strong evidence was provided in Experiments One and Two to rule out the potential contributions of three aspects of task design that may have contributed to disparate and seemingly contradictory findings in the published literature. These were: the presence/absence of copy cues at test, response requirements at test, and the difficulty of the retrieval task. Experiment Three was designed in order to test directly a "number of decisions account" for the right-frontal old/new effect (Dobbins & Han, 2006 Hayama, Johnson, & Rugg, 2008), and provided strong evidence inconsistent with such an account. A serendipitous finding in this study was evidence for a left-frontal ERP old/new effect that was functionally and electrophysiologically dissociable from the right-frontal old/new effect, and which differentiated between high and low confidence correct source judgments. There was no evidence for this effect in Experiment Four, however, when auditory (male/female voice) rather than visual (pink/yellow letters) source information was to be retrieved at test, suggesting the content-specificity of this frontally distributed ERP effect. This possibility was tested directly in Experiment Five in which versions of Experiments Three and Four were completed within-participants. Two separable frontal old/new effects were observed. These effects differed in their scalp distributions as a function of the forms of episodic content that were retrieved (i.e. visual vs. auditory source). The scalp distributions of the frontal old/new effects across Experiments Three to Five also varied according to whether the data from the first or the second halves of retrieval phases were analysed. These qualitative changes in neural activity according to time on task are interpreted in terms of processes involved in the resolution of interference, which presumably increases during the course of a retrieval task. The implications of this finding for conclusions made on the basis of averaged measures of neural activity across the entirety of a retrieval task are also discussed. In combination, the data reported in this thesis provide evidence that ERPs are sensitive to multiple neurally, functionally, and temporally distinct PFC-supported processes which operate during episodic retrieval, and offer insights into the roles played by PFC during episodic retrieval.
48
Magony, Andor Daniel. "Electrophysiology of the rat medial prefrontal cortex and amygdala during behaviour." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6102/.
Full textAbstract:
Classical Pavlovian conditioning is a relatively simple behavioural experiment where a conditioned stimulus signals the occurrence of a reward. The repeated presentation of the stimulus and the reward leads to the evolution of a conditioned response. However, the electrophysiological correlates of participating brain structures, including the medial prefrontal cortex, that plays a role in decision making, and the central nucleus of the amygdala, that is responsible for reward learning and motivation, have not yet been fully explored. This study explores the electrophysiological properties of the prefrontal cortex and the amygdala in rats during Pavlovian conditioning, extinction and reacquisition. Multisite multichannel recordings showed a significant desynchronization in response to the conditioned stimulus. Additionally, the complex nature and role of a 4Hz activity and theta oscillation in both brain structures in reward conditioning was revealed. We found a consistent power and phase regulatory mechanism coordinating the 4Hz activity, while not affecting the theta oscillation, thus rendering these two distinct oscillations, with complementary roles, to fall out of synchrony. These findings might lay the foundations for further behavioural studies, mostly in the direction of social interaction and social behaviour.
49
Thurley, Kay. "Dopamine in the prefrontal cortex and its relevance for working memory /." [S.l.] : [s.n.], 2008. http://www.zb.unibe.ch/download/eldiss/08thurley_k.pdf.
Full text
50
Driscoll, David Matthew Anderson Steven W. "The effects of prefrontal cortex damage on the regulation of emotion." Iowa City : University of Iowa, 2009. http://ir.uiowa.edu/etd/287.
Full text