Academic literature on the topic 'Inferior longitudinal fasciculus'
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Journal articles on the topic "Inferior longitudinal fasciculus"
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Borges, Kellen Christina Malheiros, Hisao Nishijo, Tales Alexandre Aversi-Ferreira, Jussara Rocha Ferreira, and Leonardo Ferreira Caixeta. "Anatomical Study of Intrahemispheric Association Fibers in the Brains of Capuchin Monkeys (Sapajussp.)." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/648128.
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Previous studies suggest that the complexity of fiber connections in the brain plays a key role in the evolutionary process of the primate brain and behaviors. The patterns of brain fiber systems have been studied in detail in many nonhuman primates, but not inSapajussp. Behavioral studies indicated thatSapajussp. (bearded capuchins) show highly cognitive behaviors such as tool use comparable to those in other nonhuman primates. To compare the brain fiber systems in capuchins with those in other nonhuman primates and humans, the intrahemispheric fibers systems in 24 cerebral hemispheres ofSapajuswere dissected by a freezing-thawing procedure. Dissection of the hemispheres in lateral view indicated short arcuate fibers, uncinate fasciculus, and inferior longitudinal fasciculus, while that in a medial view indicated short arcuate fibers, the cingulum united with the superior longitudinal fasciculus, and inferior longitudinal fasciculus. The results showed that the fiber systems inSapajusare comparable to those in rhesus and humans, except for a lack of independent superior longitudinal fasciculus and cingulum inSapajus.
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Chong, Catherine D., and Todd J. Schwedt. "Migraine affects white-matter tract integrity: A diffusion-tensor imaging study." Cephalalgia 35, no. 13 (2015): 1162–71. http://dx.doi.org/10.1177/0333102415573513.
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Background Specific white-matter tract alterations in migraine remain to be elucidated. Using diffusion tensor imaging (DTI), this study investigated whether the integrity of white-matter tracts that underlie regions of the “pain matrix” is altered in migraine and interrogated whether the number of years lived with migraine modifies fibertract structure. Methods Global probabilistic tractography was used to assess the anterior thalamic radiations, the corticospinal tracts and the inferior longitudinal fasciculi in 23 adults with migraine and 18 healthy controls. Results Migraine patients show greater mean diffusivity (MD) in the left and right anterior thalamic radiations, the left corticospinal tract, and the right inferior longitudinal fasciculus tract. Migraine patients also show greater radial diffusivity (RD) in the left anterior thalamic radiations, the left corticospinal tract as well as the left and right inferior longitudinal fasciculus tracts. No group fractional anisotropy (FA) differences were identified for any tracts. Migraineurs showed a positive correlation between years lived with migraine and MD in the right anterior thalamic radiations ( r = 0.517; p = 0.012) and the left corticospinal tract ( r = 0.468; p = 0.024). Conclusion Results indicate that white-matter integrity is altered in migraine and that longer migraine history is positively correlated with greater alterations in tract integrity.
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Serpa, M. H., J. Doshi, G. Erus, et al. "State-dependent microstructural white matter changes in drug-naïve patients with first-episode psychosis." Psychological Medicine 47, no. 15 (2017): 2613–27. http://dx.doi.org/10.1017/s0033291717001015.
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BackgroundDiffusion tensor imaging (DTI) studies have consistently shown white matter (WM) microstructural abnormalities in schizophrenia. Whether or not such alterations could vary depending on clinical status (i.e. acute psychosis v. remission) remains to be investigated.MethodsTwenty-five treatment-naïve first-episode psychosis (FEP) patients and 51 healthy-controls (HC) underwent MRI scanning at baseline. Twenty-one patients were re-scanned as soon as they achieved sustained remission of symptoms; 36 HC were also scanned twice. Rate-of-change maps of longitudinal DTI changes were calculated for in order to examine WM alterations associated with changes in clinical status. We conducted voxelwise analyses of fractional anisotropy (FA) and trace (TR) maps.ResultsAt baseline, FEP presented reductions of FA in comparison with HC [p < 0.05, false-discovery rate (FDR)-corrected] affecting fronto-limbic WM and associative, projective and commissural fasciculi. After symptom remission, patients showed FA increase over time (p < 0.001, uncorrected) in some of the above WM tracts, namely the right anterior thalamic radiation, right uncinate fasciculus/inferior fronto-occipital fasciculus, and left inferior fronto-occipital fasciculus/inferior longitudinal fasciculus. We also found significant correlations between reductions in PANSS scores and FA increases over time (p < 0.05, FDR-corrected).ConclusionsWM changes affecting brain tracts critical to the integration of perceptual information, cognition and emotions are detectable soon after the onset of FEP and may partially reverse in direct relation to the remission of acute psychotic symptoms. Our findings reinforce the view that WM abnormalities in brain tracts are a key neurobiological feature of acute psychotic disorders, and recovery from such WM pathology can lead to amelioration of symptoms.
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Fischer, David B., David L. Perez, Sashank Prasad, et al. "Right inferior longitudinal fasciculus lesions disrupt visual-emotional integration." Social Cognitive and Affective Neuroscience 11, no. 6 (2016): 945–51. http://dx.doi.org/10.1093/scan/nsw011.
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Martino, Juan, Rousinelle da Silva-Freitas, Hugo Caballero, Enrique Marco de Lucas, Juan A. García-Porrero, and Alfonso Vázquez-Barquero. "Fiber Dissection and Diffusion Tensor Imaging Tractography Study of the Temporoparietal Fiber Intersection Area." Operative Neurosurgery 72, no. 1 (2012): ons87—ons98. http://dx.doi.org/10.1227/neu.0b013e318274294b.
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Abstract Background: Lesion studies and recent surgical series report important sequelae when the inferior parietal lobe and posterior temporal lobe are damaged. Millions of axons cross through the white matter underlying these cortical areas; however, little is known about the complex organization of these connections. Objective: To analyze the subcortical anatomy of a specific region within the parietal and temporal lobes where 7 long-distances tracts intersect, ie, the temporoparietal fiber intersection area (TPFIA). Methods: Four postmortem human hemispheres were dissected, and 4 healthy hemispheres were analyzed through the use of diffusion tensor imaging-based tractography software. The different tracts that intersect at the posterior temporal and parietal lobes were isolated, and the relations with the surrounding structures were analyzed. Results: Seven tracts pass through the TPFIA: horizontal portion of the superior longitudinal fasciculus, arcuate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, optic radiations, and tapetum. The TPFIA was located deep to the angular gyrus, posterior portion of the supramarginal gyrus, and posterior portion of the superior, middle, and inferior temporal gyri. Conclusion: The TPFIA is a critical neural crossroad; it is traversed by 7 white matter tracts that connect multiple areas of the ipsilateral and contralateral hemisphere. It is also a vulnerable part of the network in that a lesion within this area will produce multiple disconnections. This is valuable information when a surgical approach through the parieto-temporo-occipital junction is planned. To decrease surgical risks, a detailed diffusion tensor imaging tractography reconstruction of the TPFIA should be performed, and intraoperative electric stimulation should be strongly considered.
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Tusa, Ronald J., and Leslie G. Ungerleider. "The inferior longitudinal fasciculus: A reexamination in humans and monkeys." Annals of Neurology 18, no. 5 (1985): 583–91. http://dx.doi.org/10.1002/ana.410180512.
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Blom-Smink, Marieke, Marjolein Verly, Kerstin Spielmann, Marion Smits, Gerard M. Ribbers, and Mieke W. M. E. van de Sandt-Koenderman. "Change in Right Inferior Longitudinal Fasciculus Integrity Is Associated With Naming Recovery in Subacute Poststroke Aphasia." Neurorehabilitation and Neural Repair 34, no. 9 (2020): 784–94. http://dx.doi.org/10.1177/1545968320940982.
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Background. Despite progress made in understanding functional reorganization patterns underlying recovery in subacute aphasia, the relation between recovery and changes in white matter structure remains unclear. Objective. To investigate changes in dorsal and ventral language white matter tract integrity in relation to naming recovery in subacute poststroke aphasia. Methods. Ten participants with aphasia after left-hemisphere stroke underwent language testing and diffusion tensor imaging twice within 3 months post onset, with a 1-month interval between sessions. Deterministic tractography was used to bilaterally reconstruct the superior longitudinal fasciculus (SLF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), middle longitudinal fasciculus (MdLF), and uncinate fasciculus (UF). Per tract, the mean fractional anisotropy (FA) was extracted as a measure of microstructural integrity. Naming accuracy was assessed with the Boston Naming Test (BNT). Correlational analyses were performed to investigate the relationship between changes in FA values and change in BNT score. Results. A strong positive correlation was found between FA change in the right ILF within the ventral stream and change on the BNT ( r = 0.91, P < .001). An increase in FA in the right ILF was associated with considerable improvement of naming accuracy (range BNT change score: 12-14), a reduction with limited improvement or slight deterioration. No significant correlations were found between change in naming accuracy and FA change in any of the other right or left ventral and dorsal language tracts. Conclusions. Naming recovery in subacute aphasia is associated with change in the integrity of the right ILF.
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Lin, Yueh-Hsin, Nicholas B. Dadario, Jorge Hormovas, et al. "Anatomy and White Matter Connections of the Superior Parietal Lobule." Operative Neurosurgery 21, no. 3 (2021): E199—E214. http://dx.doi.org/10.1093/ons/opab174.
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Abstract BACKGROUND The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus. OBJECTIVE To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth. METHODS Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement. RESULTS We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected. CONCLUSION The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region.
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Sundram, F., Q. Deeley, S. Sarkar, et al. "P02 - 361 White matter microstructural abnormalities in antisocial personality disorder: A pilot diffusion tensor imaging study." European Psychiatry 26, S2 (2011): 957. http://dx.doi.org/10.1016/s0924-9338(11)72662-1.
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IntroductionAntisocial personality disorder (ASPD) and psychopathy involve significant interpersonal and behavioural impairments. However, little is known about white matter (WM) abnormalities in tracts linking grey matter regions. A previous diffusion tensor imaging (DT-MRI) tractography study in ASPD and psychopathy revealed abnormalities in the right uncinate fasciculus, indicating fronto-limbic disconnectivity.ObjectivesIt is not clear whether WM abnormalities are restricted to only this tract or are more widespread. Therefore, we planned to use whole brain DT-MRI voxel-based analyses.AimsTo clarify if WM abnormalities extend beyond the frontal lobe.MethodsWe used whole brain DT-MRI to compare WM fractional anisotropy (FA) of 15 adults with ASPD and healthy age, handedness and IQ-matched controls. Also, within ASPD subjects, we related differences in FA to severity of psychopathy measures.ResultsSignificant WM FA reductions were found in ASPD subjects relative to controls. These were found bilaterally in the anterior corpus callosum. Right hemisphere FA reduction was found in the anterior corona radiata, uncinate fasciculus, inferior fronto-occipital fasciculus and internal capsule. Left hemisphere, FA deficits encompassed the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and internal capsule. There was a significant negative correlation between WM FA in the right uncinate fasciculus and corpus callosum and measures of psychopathy.ConclusionsWe report FA reduction in the uncinate fasciculus and anterior corpus callosum which may be associated with frontal and inter-hemispheric disconnectivity in ASPD, in addition to abnormalities in other tracts which directly or indirectly connect to prefrontal regions.
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Bassell, Julia, Siddharth Srivastava, Anna K. Prohl, et al. "Diffusion Tensor Imaging Abnormalities in the Uncinate Fasciculus and Inferior Longitudinal Fasciculus in Phelan-McDermid Syndrome." Pediatric Neurology 106 (May 2020): 24–31. http://dx.doi.org/10.1016/j.pediatrneurol.2020.01.006.
Full textDissertations / Theses on the topic "Inferior longitudinal fasciculus"
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Shin, Jiwon. "Efficiency of semantic processing measured by N400m and its correlation with anisotropy of the inferior longitudinal fasciculus." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121312.
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The inferior longitudinal fasciculus (ILF) is a white matter tract that connects the occipital and the temporal lobes. Due to its location, a possible role in visual processing and language comprehension has been attributed to the ILF. The present study aims to investigate the existence and degree of an effect of the ILF's structural organization on visual semantic processing. We hypothesized that the efficiency of visual semantic processing positively correlates with the degree of anisotropy of the ILF. We studied 10 healthy right-handed subjects. We extracted N400m from magnetoencephalography (MEG) signals during a semantic decision task and determined fractional anisotropy (FA) of the ILF using diffusion tensor imaging (DTI). By comparing inter-individual differences in N400m and FA, we found that FA of the left ILF negatively correlated with the N400m latency, which suggests that high ILF anisotropy is associated with more efficient semantic processing. Our findings provide supporting evidence for a role of the ILF in language comprehension.<br>Le faisceau longitudinal inférieur est une fibre nerveuse de la substance blanche qui connecte les lobes occipital et temporal. En raison de son emplacement, un rôle possible dans le traitement visuel et la comprehension du langage, a été attribué au faisceau longitudinal inférieur. Cette étude a pour but d'examiner l'existence et le degré de l'effet de l'organisation structurelle du faisceau longitudinal inférieur sur le traitement visuel sémantique. Nous émettons l'hypothèse que l'efficacité du traitement visuel sémantique est corrélée positivement avec le degré d'anisotropie du faisceau longitudinal inférieur. Nous avons étudié 10 sujets sains en santé. Nous avons extrait N400m de signaux de la magnétoencéphalographie pendant une tâche de décision sémantique et avons déterminé l'anisotropie fractionnelle du faisceau longitudinal inférieur en utilisant l'imagerie du tenseur de diffusion. En comparant les différences inter-individuelles dans N400m et l'anisotropie fractionnelle, nous avons découvert que l'anisotropie fractionnelle du faisceau longitudinal inférieur dans l'hémisphère gauche corrélée négativement avec la latence de N400m, suggérant que l'anisotropie élevée du faisceau longitudinal inférieur est associée avec un traitement sémantique plus efficace. Nos résultats fournissent des preuves à l'appui d'un rôle du faisceau longitudinal inférieur dans la compréhension du langage.
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Lima, Maldonado Igor. "Vers une anatomie fonctionnelle de la substance blanche cérébrale chez l'homme : Étude par dissection de fibres et électrostimulation des voies du langage." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20137/document.
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La connaissance de la forme et de la fonction des faisceaux d'association aide à la modélisation des réseaux cognitifs, sert au développement d'abords neurochirurgicaux et à l'interprétation de la neuro-imagerie. Nous avons employé une approche hybride anatomique et neurophysiologique dont l'objectif principal a été la caractérisation des sous-parties du complexe faisceau longitudinal supérieur / faisceau arqué (FLS/FA) et de leur participation dans les fonctions langagières articulatoire, phonologique et sémantique. Soixante-huit hémisphères cérébraux ont été préparés par une variante de la technique de dissection de fibres connue sous le nom de méthode de Klingler. En parallèle, nous avons étudié les cartographies fonctionnelles électriques de quatorze patients opérés en condition éveillée pour des tumeurs cérébrales dans le carrefour temporo-pariétal de l'hémisphère dominant. En se basant sur nos constatations en laboratoire, sur la neuro-imagerie et sur la littérature disponible, nous avons procédé à la mise en corrélation des manifestations cliniques provoquées par la stimulation électrique et la topographie des faisceaux d'association. Les préparations anatomiques ont permis d'étudier l'organisation tridimensionnelle de la substance blanche hémisphérique, de réaliser la première description par dissection de fibres du faisceau longitudinal moyen et de caractériser trois composants du FLS/FA : le majeur, le ventral et l'arqué. L'existence d'un composant dorsal le long du bord supérieur de l'hémisphère, hypothèse basée sur l'anatomie du primate non humain et sur la neuro-imagerie, n'a pas été confirmée. L'anatomie fonctionnelle du lobule pariétal inférieur a été revisitée ainsi que celle des voies de substance blanche à l'intérieur. La variabilité interindividuelle dans la distribution des aires fonctionnelles a été évidente, surtout pour le langage. Ces aires ont servi à délimiter la résection tumorale, à savoir : le cortex sensitif primaire, en avant ; l'aire de Wernicke, en inféro-latéral ; et les voies de substance blanche du FLS/FA en profondeur. A ce niveau, l'observation des manifestations cliniques induites par la perturbation électrique ont permis de conclure que le composant ventral operculaire du FLS/FA joue un rôle dans la fonction articulatoire et que le composant arqué, plus profond, est impliqué dans la fonction phonologique. L'exploration fonctionnelle n'a pas fourni d'argument en faveur d'une participation de ce complexe associatif dans le traitement sémantique, une hypothèse de la littérature basée sur la neuro-imagerie uniquement. Ces constatations peuvent avoir des implications importantes, tant dans la pratique clinique que dans la recherche fondamentale, notamment en ce qui concerne la modélisation des bases neurales du langage<br>The knowledge of the form and function of fiber pathways supports the modeling of cognitive networks, the development of neurosurgical approaches and the interpretation of neuroimaging. We used a hybrid anatomical and neurophysiological methodology whose main objective was to characterize the subunits of the complex comprised of the Superior Longitudinal and the Arcuate Fasciculus (SLF/AF) as well as their participation in the articulatory, phonological and semantic language functions. Sixty-eight cerebral hemispheres were prepared using a variant of the fiber dissection technique known as the Klingler's method. In parallel, we studied the electrical functional maps of fourteen patients operated on using a sleep-awake-sleep technique for brain tumors of the temporo-parietal junction in the dominant hemisphere. Based on our laboratory and neuroimaging findings, as well as on the available literature, we conducted a correlation of clinical manifestations caused by the electrical stimulation and the topography of the association bundles. The anatomical preparations allowed us to detail the three-dimensional organization of hemispheric white matter, to perform the first description of the Middle Longitudinal Fasciculus using fiber dissection, and to characterize three of the four components of the SLF: the major, the ventral and the arcuate. The existence of a dorsal component along the superior edge of the hemisphere was not confirmed by our findings, a hypothesis in the literature that was based on the anatomy of the nonhuman primate and on previous studies on neuroimaging. The functional anatomy of the inferior parietal lobule was revisited as well as the pathways of white matter in its depth. The inter-individual variability in the distribution of eloquent areas was evident, especially for language. These areas were used to delineate the tumor resection, namely: the primary sensory cortex, anteriorly; the Wernicke's area, inferiorly and laterally, and the white matter pathways from the SLF/AF in the white matter. At this level, the observation of the clinical manifestations in connection with the electrical disturbance caused by the cerebral stimulation allowed us to conclude that the ventral opercular component of the SLF has a role in the articulatory function and the deeper arcuate component is involved in the phonological function. The functional mapping does not provide any argument for a participation of this association complex in the treatment of semantics, an assumption in the literature that was based only on neuroimaging. These findings may have important implications, both in clinical practice and in fundamental research, including for modeling the neural basis of language
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Bradstreet, Lauren E. "The Examination of White Matter Microstructure, Autism Traits, and Social Cognitive Abilities in Neurotypical Adults." 2014. http://scholarworks.gsu.edu/psych_theses/127.
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The purpose of this study was to examine the relationships among mentalizing abilities, self-reported autism traits, and two white matter tracts, uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF), in neurotypical adults. UF and ILF were hypothesized to connect brain regions implicated in a neuroanatomical model of mentalizing. Data were available for 24 neurotypical adults (mean age = 21.92 (4.72) years; 15 women). Tract-based spatial statistics (TBSS) was used to conduct voxelwise cross-participant comparisons of fractional anisotropy (FA) values in UF and ILF as predicted by mentalizing abilities and self-reported autism traits. Self-reported autism traits were positively related to FA values in left ILF. Results suggest that microstructural differences in left ILF are specifically involved in the expression of subclinical autism traits in neurotypical individuals.
Book chapters on the topic "Inferior longitudinal fasciculus"
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Schmahmann, Jeremy D., and Deepak N. Pandya. "Inferior Longitudinal Fasciculus." In Fiber Pathways of the Brain. Oxford University Press, 2006. http://dx.doi.org/10.1093/acprof:oso/9780195104233.003.0018.
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Leigh, R. John, and David S. Zee. "The Neural Basis for Conjugate Eye Movements." In The Neurology of Eye Movements. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199969289.003.0007.
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This chapter draws on a range of studies of macaque and humans to forge an anatomical scheme for the control of gaze. At each stage, this scheme is used to predict effects of focal lesions on the control of gaze, with video examples. Contributions include the abducens nucleus, medial longitudinal fasciculus (MLF), and paramedian pontine reticular formation (PPRF) to horizontal gaze; the rostral interstitial nucleus of the medial longitudinal fasciculus (RIMLF), interstitial nucleus of Cajal, and posterior commissure to vertical gaze; cerebellar flocculus, paraflocculus, dorsal vermis, fastigial nucleus, and inferior olive to adaptive optimization of gaze. Cortical control of gaze by structures including primary visual cortex (V1), middle temporal visual area (MT, V5), medial superior temporal visual area (MST), posterior parietal cortex, frontal eye fields, supplementary eye fields, dorsolateral prefrontal cortex, cingulate cortex, descending pathways, thalamus, pulvinar, caudate, substantia nigra pars reticulata, subthalamic nucleus, and superior colliculus are each discussed.
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Wong, Agnes. "Ocular Motor Disorders Caused by Lesions in the Cerebellum." In Eye Movement Disorders. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195324266.003.0018.
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The vestibulocerebellum consists of the flocculus, ventral paraflocculus, nodulus, and uvula. ■ The flocculus receives inputs from the vestibular nucleus and nerve, nucleus prepositus hypoglossi (NPH), inferior olivary nucleus, cell groups of the paramedian tracts (PMT), nucleus reticularis tegmenti pontis (NRTP), and mesencephalic reticular formation. ■ The ventral paraflocculus receives inputs from contralateral pontine nuclei. ■ Project to ipsilateral superior and medial vestibular nuclei, and the y-group ■ Receive input from the medial and inferior vestibular nuclei, vestibular nerve, NPH, and inferior olivary nucleus ■ Project to the vestibular nuclei ■ The oculomotor vermis consists of parts of the declive, folium, tuber, and pyramis. ■ Receives inputs from the inferior olivary nucleus, vestibular nuclei, NPH, paramedian pontine reticular formation (PPRF), NRTP, and dorsolateral and dorsomedial pontine nuclei ■ Projects to the caudal fastigial nucleus ■ Stimulation of the Purkinje cells in the dorsal vermis elicits contralaterally directed saccades and smooth pursuit ■ Receives inputs from the dorsal vermis, inferior olivary nucleus, and NRTP ■ Decussates and projects via the uncinate fasciculus of the brachium conjunctivum to the contralateral PPRF, rostral interstitial nucleus of the medial longitudinal fasciculus, nucleus of the posterior commissure, omnipause neurons in nucleus raphe interpositus, the mesencephalic reticular formation, and superior colliculus ■ Neurons in the fastigial oculomotor region (FOR) fire during both ipsilateral and contralateral saccades. 1. The contralateral FOR neurons burst before the onset of saccade, and the onset of firing is not correlated with any property of the saccade. 2. Conversely, the time of onset for neurons in the ipsilateral FOR varies, with bursts occurring later for larger saccades. 3. Thus, the difference in time of onset between contralateral and ipsilateral FOR activity encodes the amplitude of saccades (i.e., the larger the difference in time of onset, the larger the saccade amplitude). Eye movement abnormalities in uncinate fasciculus lesion include hypometric ipsilesional saccades and hypermetric contralesional saccades (“contrapulsion”). Arnold-Chiari malformation is a malformation of the medullary–spinal junction with herniation of intracranial contents through the foramen magnum. The three types are illustrated in the figure below.
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Wong, Agnes. "Nuclear and Infranuclear Ocular Motor Disorders." In Eye Movement Disorders. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195324266.003.0021.
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Binocular diplopia is usually caused by strabismus, whereas monocular diplopia is usually caused by ocular diseases. Incomitant diplopia is usually caused by an acquired strabismus resulting from abnormal innervation or mechanical restriction. The oculomotor (third) nerve: ■ Innervates the medial rectus, superior rectus, inferior rectus, inferior oblique, and levator palpebrae muscles ■ Carries parasympathetic fibers to the iris sphincter and the ciliary body. ■ Common causes of third nerve palsy: Adults: aneurysms, vascular disease (including ischemia, diabetes, hypertension, and inflammatory arteritis), trauma, migraine Children: birth trauma, accidental trauma, neonatal hypoxia, migraine The third nerve originates from the oculomotor nucleus complex, which lies at the ventral border of the periaqueductal gray matter in the midbrain. The nerve fascicle passes ventrally through the medial longitudinal fasciculus, the tegmentum, the red nucleus, and the substantia nigra, and finally emerges from the cerebral peduncle to form the oculomotor nerve trunk, which lies between the superior cerebellar and posterior cerebral arteries. The nerve then passes through the subarachnoid space, running beneath the free edge of the tentorium. It continues lateral to the posterior communicating artery and below the temporal lobe uncus, where it runs over the petroclinoid ligament. It pierces the dura mater at the top of the clivus to enter the cavernous sinus. Within the cavernous sinus, the nerve runs along the lateral wall of the sinus together with the trochlear nerve and the ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve. As it leaves the cavernous sinus, it divides into the superior and inferior divisions, which pass through the superior orbital fissure, and enters the orbit within the annulus of Zinn. Within the orbit, the smaller superior division runs lateral to the optic nerve and ophthalmic artery and supplies the superior rectus and levator palpebrae muscles. The larger inferior division supplies the medial rectus, inferior rectus, and inferior oblique muscles, as well as the iris sphincter and ciliary body.