This thesis investigates sensorimotor adaptive mechanisms that maintain the accuracy of goal-directed saccades in amblyopia, a developmental disorder characterized by impairment of spatiotemporal visual processing. Saccadic adaptation was induced by displacing the visual target toward initial fixation during the saccade. Eleven visually normal controls and seven patients with amblyopia were tested binocularly and monocularly with the amblyopic and fellow eye (non-dominant and dominant eye in controls) in three separate sessions. Patients with amblyopia exhibited reduced adaptation of saccadic gain compared to controls when viewing with the amblyopic eye and binocularly. Initiation of saccades was also delayed in patients when viewing with the amblyopic eye. It is proposed that the adaptive ability to modify the initial saccadic motor commands for maintaining short-term saccadic accuracy is impaired in amblyopia due to imprecise error signals. Moreover, this thesis reaffirms the notion that the error signals driving saccadic adaptation are visual in nature.

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Master of Science in Medicine / Saccadic and vestibular-evoked eye movements are similar in that their three-dimensional kinematic properties show eye position-dependence. When the line of sight is directed towards an eccentric target, the eye velocity axis tilts in a manner that depends on the instantaneous position of the eye in the head, with the magnitude of tilt also depending on whether the eye movement is saccadic or vestibular-evoked. The mechanism responsible for producing eye velocity axis tilting phenomena is not well understood. Some authorities have suggested that muscle pulleys in the orbit are critical for implementing eye velocity axis tilting, while others have suggested that the cerebellum plays an important role. In the current study, three-dimensional eye and head rotation data were acquired, using the magnetic search coil technique, to confirm the presence of eye position-dependent eye velocity axis tilting during saccadic eye movements. Both normal humans and humans with cerebellar atrophy were studied. While the humans with cerebellar atrophy were noted to have abnormalities in the two-dimensional metrics and consistency of their saccadic eye movements, the eye position-dependent eye velocity axis tilts were similar to those observed in the normal subjects. A mathematical model of the human saccadic and vestibular systems was utilized to investigate the means by which these eye position-dependent properties may arise for both types of eye movement. The predictions of the saccadic model were compared with the saccadic data obtained in the current study, while the predictions of the vestibular model were compared with vestibular-evoked eye movement data obtained in a previous study. The results from the model simulations suggest that the muscle pulleys are responsible for bringing about eye position-dependent eye velocity axis tilting for both saccadic and vestibular-evoked eye movements, and that these phenomena are not centrally programmed.

Thesis (Ph.D.)--Murdoch University, 2006. / Thesis submitted to the Division of Health Sciences. Bibliography: leaves 176-207.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 21-24). Also available via the World Wide Web.

Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2009. / Full text also available online. Scroll down for electronic link.

Why do we need to sleep? Not only is getting enough sleep important for our overall health and well-being, it is perhaps of utmost importance for normal brain functioning. Scientific findings derived from studying sleep deprivation suggests that sleep also plays an important role in our emotional functioning, which has led researchers to propose a causal and intimate relationship between sleep and emotional brain functioning. Without sleep it seems as our emotional processing become impaired in various ways. Along with advances in cognitive neuroscience, it is now possible to characterize mechanisms underlying emotional brain processes. In pursuit of the possible functions of sleep, researchers have also proposed that rapid eye movement sleep, might support a process of affective brain homeostasis and recalibration that optimally prepares the organism for next-day social and emotional functioning. This thesis reviews current behavioral and neurophysiological evidence focused on the relationship between sleep and emotional brain functioning, and the role of rapid eye movement sleep in emotional processing.

L’Eye Tracking est une méthode de mesure précise et non invasive des mouvements oculaires permettant d’accéder aux paramètres neurophysiologiques du système oculomoteur. L’analyse des mouvements oculaires est un outil qui contribue au diagnostic des syndromes parkinsoniens. En Guadeloupe, les syndromes parkinsoniens atypiques, sont présents en proportion anormalement élevée. Ils représentent environ 70% des syndromes parkinsoniens. Notre travail a été de réaliser des normes oculomotrices des sujets sains et de caractériser les syndromes parkinsoniens sur le plan oculomoteur à partir des normes oculomotrices réalisées. Les normes oculomotrices des sujets sains antillais différents de celles des témoins d’origine tchèque. Ces différences suggèrent la possibilité d’une variabilité des standards oculomoteurs entre deux populations de sujets sains. Nos résultats témoignent de la nécessité de constituer des groupes témoins spécifiques à la population étudiée lors des études cliniques et les travaux de recherche sur les mouvements oculaires. Ils soulèvent également la question de l’influence de facteurs génétiques et/ou environnementaux sur les paramètres oculomoteurs. Les patients porteurs d’une maladie de Parkinson originaires et résidants aux Antilles présentent des anomalies oculomotrices plus fréquentes qu’attendues avec notamment un taux élevé d’erreurs aux antisaccades. Cette caractéristique ne semble pas corrélée aux performances cognitives. Chez les parkinsoniens atypiques l’altération parfois sévère de l’ensemble des paramètres oculomoteurs est en accord avec les données cliniques et d’imagerie cérébrale et témoignent de lésions diffuses corticales fronto-pariétales et sous corticales. / Eye Tracking is a precise and non-invasive method of measuring eye movements that provides access to the neurophysiological parameters of the oculomotor system. Eye movement analysis is a tool that contributes to the diagnosis of parkinsonian syndromes. In Guadeloupe, atypical parkinsonian syndromes are present in an abnormally high proportion. They represent about 70% of Parkinson's syndromes. Our work has been to achieve oculomotor standards of healthy subjects and characterize the parkinsonian syndromes on the oculomotor level from oculomotor standards. The oculomotor standards of Caraibbean healthy subjects differ from those of Czech origin. These differences suggest the possibility of variability of oculomotor standards between two populations of healthy subjects. Our results demonstrate the need to establish control groups specific to the population studied in clinical studies and research work on eye movements. They also raise the question of the influence of genetic and / or environmental factors on oculomotor parameters. Patients with Parkinson's disease coming from and residing in the Caribbean have more frequent oculomotor abnormalities than expected with a high percentage of error in antisaccade task. This characteristic does not seem to correlate with cognitive performance. In atypical parkinsonian patients, there are severe deterioration of all the oculomotor parameters is in agreement with the clinical and cerebral imaging data and show diffuse fronto-parietal and sub-cortical cortical lesions

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第17819号 / 医博第3817号 / 新制||医||999(附属図書館) / 30634 / 京都大学大学院医学研究科医学専攻 / (主査)教授 金子 武嗣, 教授 大森 治紀, 教授 福山 秀直 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

La schizophrénie est un trouble mental qui touche environ 1% de la population mondiale et qui représente l’une des principales causes de handicap psychique. Depuis plusieurs années, des nombreuses études ont montré la présence d’anomalies oculomotrices ainsi que de la motricité fine chez des sujets appartenant au spectre la schizophrénie, soulignant l’intérêt d’approfondir la recherche de biomarqueurs dans cette pathologie. Dans cette thèse nous avons réalisé trois études afin d’examiner l’oculomotricité et la présence de signes neurologiques mineurs (SNM, NSS, Neurological Soft Signs) chez des patients avec schizophrénie, des apparentés sains des patients ainsi que des sujets à haut risque de developper une psychose (UHR) en les comparant avec des sujets contrôles. Pour la première fois nous nous avons enregistré les saccades mémorisées chez des sujets UHR en relation aux SNM (etude 1). Les résultats nous ont montré que les sujets avec schizophrénie, les apparentés sains et les sujets UHR rapportaient plus d’erreurs aux saccades mémorisées par rapport aux sujets contrôles, plus précisément les UHR ayant un nombre plus importants des SNM. L’etude 2 nous a permis d’élargir les investigations en étudiant l’instabilité de la fixation visuelle ainsi que la poursuite. Les résultats nous ont monté une instabilité de la fixation ainsi qu’un default du contrôle saccadique à la poursuite surtout chez les patients avec une présence plus important des SNM. Enfin, l’étude 3, en utilisant la méthode d’apprentissage automatique nous avons pu développer un modèle de machine à vecteurs de support avec l’objectif de pouvoir évaluer les valeurs prédictives différentielles pour mieux discriminer nos quatre groupes de sujets. Cette analyse nous a permis de souligner l’importance de la prise en compte des paramètres oculomoteurs ainsi que des Signes Neurologiques Mineurs dans l’étude sur la détection précoce de la schizophrénie. / Schizophrenia is a mental disorder that affects about 1% of the world's population and it represent one of the main causes of psychological disability. During several years, numerous studies have shown the presence of oculomotor as well as fine motor skills abnormalities in subjects belonging the spectrum of schizophrenia, highlighting the interest to deepen the search for biomarkers in this pathology.During my PhD’s thesis we conducted three studies to examine the oculomotor capability and the presence of Neurological Soft Signs (NSS) in patients with schizophrenia, full siblings of patients and subjects at Ultra High Risk for developing Psychosis (UHR) compared to health volunteers. For the first time we recorded memory guided saccades in UHR subjects in relation to the NSS (study 1). The results showed that subjects with schizophrenia, full siblings and UHR made more errors in this task when they were compared to control, particularly for UHR’s group with a higher score of NSS. The second study (study 2) allowed us to enlarged the investigations of visual fixation as well as of the pursuit eye movements. The results showed an instability of the fixation as well as a lack of saccadic control during pursuit especially for patients with a higher score of NSS. Finally, in the study 3, we used the machine learning method on the data to evaluate predictive values to better discriminate the four groups of subjects. This analysis allowed us to underline the importance of taking into account oculomotor parameters as well as the Neurological Soft Signs for the early detection of schizophrenia.