To find if video enjoyment was deeper for people with ADHD (attention deficit/hyperactive disorder) than for their non-ADHD peers, subjects with ADHD, and without, had their eye movement tracked during video exposure to determine average saccade rates. I interviewed subjects using pre-tested statements to establish periods of flow state (a measure of enjoyment). Results indicate that there is a deeper sense of enjoyment for people with ADHD, as subjects with ADHD passed a greater average time in flow state during video consumption (27% compared to 21%). Furthermore, the effects of flow state on the eye movement of those with ADHD was much greater than the effects of flow state on the eye movement of the non-ADHD control group. Average saccade rates jumped up 0.15 saccades per second when comparing out-of-flow to in-flow states for the ADHD group, while the average saccade rate for the non-ADHD group increased only 0.03 saccades per second when comparing out-of-flow to in-flow states. This helps further understanding of why people with ADHD consume more screen time than their non-ADHD peers; they may be more inclined to choose video consumption as an activity since the enjoyment they receive from video consumption is deeper and more frequent.

" - Comment apprécions-nous la complexité du monde qui nous entoure ? - En bougeant nos yeux ! - Pourquoi ? - Parce qu'une perception visuelle efficace (avec une acuité maximale !) nécessite de placer l'image des éléments pertinents du champ visuel au niveau d'une petite partie de notre rétine : la fovéa. " Les saccades oculaires sont les mouvements les plus rapides que peut produire notre organisme et sont malgré tout très précises. Le contrôle de ces mouvements représente un défi pour notre cerveau. En effet, ces saccades sont tellement rapides qu'aucune information visuelle ne peut modifier leur trajectoire en cours d'exécution. Mais alors, de quels moyens dispose notre cerveau pour maintenir ces performances tout au long de notre vie? En cas d'imprécision répétée, des mécanismes vont progressivement modifier l'amplitude de nos saccades oculaires afin d'en rétablir la précision. Cette adaptation saccadique repose sur des modifications centrales plastiques. Ce travail de thèse a comme vocation d'élucider les caractéristiques de l'adaptation saccadique chez l'homme. Des approches complémentaires ont permis d'étudier d'une part, l'adaptation des deux grandes catégories de saccades, réactives et volontaires, et d'autre part, l'adaptation en diminution et en augmentation d'amplitude. Nos données permettent de disséquer les mécanismes d'adaptation saccadique dans leur complexité et de mettre en évidence des structures neuronales indispensables à leur mise en place. Notre travail constitue également le support pour le développement de nouvelles procédures de rééducation, basées sur la plasticité oculomotrice.

Microsaccades are an important component of the small eye movements that constitute fixation, the basis of visual perception. The specific function of microsaccades has been a long-standing research problem. Only recently, conclusive evidence emerged, showing that microsaccades aid both visual perception and oculomotor control. The main goal of this thesis was to improve our understanding of the implementation of microsaccade generation within the circuitry of saccade control, an unsolved issue in oculomotor research. We make a case for a model according to which microsaccades and saccades result from mutually dependent motor plans, competing for expression. The model consists of an activation field, coding for fixation at its center and for saccades at peripheral locations; saccade amplitude increases with eccentricity. Activity during fixation spreads to slightly peripheral locations in the field and, thus, may result in the generation of microsaccades. Inhibition of remote and excitation of neighbouring locations govern the dynamics of the field, resulting in a strong competition between fixation and saccade generation. We propose that this common-field model of microsaccade and saccade generation finds a neurophysiological counterpart in the motor map of the superior colliculus (SC), a key brainstem structure involved in the generation of saccades. In a series of five behavioral experiments, we tested implications of the model. Predictions were derived concerning (1) the behavior of microsaccades in a given task (microsaccade rate, amplitude, and direction), (2) the interactions of microsaccades and subsequent saccades, and (3) the relationship between microsaccadic behavior and neurophysiological processes at the level of the SC. The results yielded strong support for the model at all three levels of analysis, suggesting that microsaccade statistics are indicative of the state of the fixation-related part of the SC motor map. / Mikrosakkaden sind ein wichtiger Bestandteil der kleinen Augenbewegungen, aus denen Fixationen, die Basis der visuellen Wahrnehmung, bestehen. Neuere Arbeiten erbrachten schlüssige Evidenz dafür, das Mikrosakkaden eine wichtige Rolle in der Wahrnehmung und der Blickbewegungskontrolle spielen. Hauptanliegen dieser Dissertation war es, unser Verständnis der Implementierung der Generierung von Mikrosakkaden im Kreislauf der Sakkadensteuerung zu vertiefen. Wir schlagen ein Modell vor, in dem Mikrosakkaden und Sakkaden konkurrierende Bewegungsprogramme darstellen, die um ihre Umsetzung wettstreiten. Das Modell besteht aus einem Aktivationsfeld, in dem Fixation im Zentrum und Sakkaden in der Peripherie repräsentiert sind (Sakkadenamplitude steigt mit der Exzentrizität). Aktivität während der Fixation breitet sich zu leicht peripheren Orten im Feld aus und kann so zur Generierung von Mikrosakkaden führen. Hemmung von entfernten und Erregung von benachbarten Orten bestimmen die Dynamik im Feld, was zu einem starken Wettstreit zwischen Fixation und Sakkadengenerierung beiträgt. Wir schlagen vor, dass dieses common-field model of microsaccade and saccade generation ein neurophysiologisches Pendant in der Bewegungskarte des colliculus superior (CS) findet, einer Struktur im Hirnstamm, die im starken Zusammenhang mit der Entstehung von Sakkaden steht. In fünf behavioralen Experimenten wurden Implikationen des Modells überprüft. Vorhersagen wurden auf drei Ebenen abgeleitet: (1) Verhalten der Mikrosakkaden in bestimmten Aufgaben (Mikrosakkadenrate, -amplitude und -richtung), (2) Interaktionen von Mikrosakkaden und nachfolgenden Sakkaden, (3) der Zusammenhang zwischen Mikrosakkadenverhalten und neurophysiologischen Prozessen auf der Ebene des CS. Die Ergebnisse unterstützten das Modell auf allen drei Analyseebenen. Mikrosakkaden scheinen ein Indikator der Fixationsaktivität in der Bewegungskarte des CS zu sein.

" - Comment apprécions-nous la complexité du monde qui nous entoure ?- En bougeant nos yeux !- Pourquoi ?- Parce qu'une perception visuelle efficace (avec une acuité maximale !) nécessite de placer l'image des éléments pertinents du champ visuel au niveau d'une petite partie de notre rétine : la fovéa. " Les saccades oculaires sont les mouvements les plus rapides que peut produire notre organisme et sont malgré tout très précises. Le contrôle de ces mouvements représente un défi pour notre cerveau. En effet, ces saccades sont tellement rapides qu'aucune information visuelle ne peut modifier leur trajectoire en cours d'exécution. Mais alors, de quels moyens dispose notre cerveau pour maintenir ces performances tout au long de notre vie? En cas d'imprécision répétée, des mécanismes vont progressivement modifier l'amplitude de nos saccades oculaires afin d'en rétablir la précision. Cette adaptation saccadique repose sur des modifications centrales plastiques. Ce travail de thèse a comme vocation d'élucider les caractéristiques de l'adaptation saccadique chez l'homme. Des approches complémentaires ont permis d'étudier d'une part, l'adaptation des deux grandes catégories de saccades, réactives et volontaires, et d'autre part, l'adaptation en diminution et en augmentation d'amplitude. Nos données permettent de disséquer les mécanismes d'adaptation saccadique dans leur complexité et de mettre en évidence des structures neuronales indispensables à leur mise en place. Notre travail constitue également le support pour le développement de nouvelles procédures de rééducation, basées sur la plasticité oculomotrice.

Human vision is remarkable. By limiting the main concentration of high-acuity photoreceptors to the eye's central fovea region, we efficiently view the world by redirecting the fovea between points of interest using eye movements called <em>saccades</em>. <br /><br /> Part I describes a saccadic vision system prototype design. The dual-resolution saccadic camera detects objects of interest in a scene by processing low-resolution image information; it then revisits salient regions in high-resolution. The end product is a dual-resolution image in which background information is displayed in low-resolution, and salient areas are captured in high-acuity. This lends to a resource-efficient active vision system. <br /><br />Part II describes CMOS image sensor designs for active vision. Specifically, this discussion focuses on methods to determine regions of interest and achieve high dynamic range on the sensor.

Šio baigiamojo bakalauro darbo tyrimo tikslas ištirti akies ir rankos koordinuotų judesių savybes sekant taikinį skirtingo pločio labirintais, taikiniui judant skirtingais greičiais. Akių judesiams registruoti buvo panaudota EyeGaze System, o rankos judesiams registruoti - WACOM Intuos® 2 XD-1212-U grafinė planšetė. Tiriamiesiems reikėjo pravesti taikinį trim skirtingo pločio labirintais. Tyrimo metu buvo registruojami akių ir rankos judesiai, pagal kurios buvo analizuojami žvilgsnio šuolio amplitudės, atstumas tarp rankos ir žvilgsnio prieš įvykstant žvilgsnio šuoliui, akies ir rankos greičių santykis bei gautieji rezultatai įvertinti remiantis Fitso dėsniu, kuris įvertino, kaip tiksliai ir greitai tiriamieji atliko labirintus. Gautieji rezultatai parodė, kad didėjant rankos greičiui ir esant platesniam labirintui žvilgsnio šuolių amplitudžių ir atstumo tarp rankos ir žvilgsnio prieš įvykstant žvilgsnio šuoliui vidurkiai bei jų standartiniai nuokrypiai didėja. Akies ir greičio santykis parodė, kad esant mažesniems greičiams akis lenkia ranką, o didėjant ranka pralenkia akį. Tyrimo rezultatai gali būti panaudoti kuriant robotų programinę įranga, neurofiziologinių procesų analizei bei įvertinti žmogaus koordinaciją reabilitacijos metu. / The theme of Bachelor project of Electronics engineering is important for research in biomedical engineering. In my purpose is to investigate eye-hand coordination during target guiding by hand along labyrinth. Investigatives have to guide a target in different wide of labyrinth. First they have to guide a target in the narrowest labyrinth, which wide is 10 px, later in the widest labyrinth, which wide is 39 px and last in moderate labyrinth, which wide is 15 px. In this labyrinth investigatives have to guide targets of two different sizes. They have to guide at different speed and precision. Eye coordinates were recorded by EyeGaze System, which produced LC Technologies, Ltd. Hand coordinates were recorded by WACOM Intuos® 2 XD-1212-U graphic tablet. During the research recorded eye and hand coordinates, which were analysed. Due to this information, were calculated gaze jump amplitudes, distance between the gaze and hand before gaze will do a jump, gaze and hand speed ratio and results were evaluated by Fitts‘s law. Results revealed that average and standart deviation of these parameters are major if speed of target becomes faster and labyrinth is wider. Gaze and hand speed ratio revealed, that at slow speed gaze overtake a hand and vice versa. In accordance with results, which were evaluated by Ftts‘s law, revealed that the longest duration and least precision are in the narrowest labyrinth. The shortest duration and the best precision are in the widest labyrinth... [to full text]

Game theory outlines optimal response strategies during mixed-strategy competitions in which available actions are selected probabilistically. The neural processes involved in choosing individual strategic actions, however, remain poorly understood. Here, actions need to be selected (1) in the absence of sensory instruction or reward cues and (2) independent of previous events. This thesis examines the neural processes involved in action selection during mixed-strategy competition. To do so, we both measured and manipulated presaccadic activity in the primate superior colliculus (SC), a structure involved in the generation of orienting saccadic eye movements, during a strategic game. The first study tested whether the SC is involved in choosing saccades under strategic conditions. Monkeys were free to choose either of two saccade targets as they competed against a computer opponent during the mixed-strategy game ‘matching-pennies’. The accuracy with which pre-saccadic SC activity predicted upcoming choice gradually increased in the time leading up to the saccade. Probing the SC with supra-threshold stimulation demonstrated that these evolving signals were functionally involved in preparing strategic saccades. Finally, sub-threshold stimulation of the SC increased the likelihood that contralateral saccades were selected. In the second study, we compared the influence of previous actions and rewards on updating premotor activity in the SC in the strategic condition where eliciting stochastic responses was optimal and in a non-strategic condition where stochastic responses were also elicited but through explicit instruction. To avoid exploitation by opponents during mixed-strategy competitions one should select behaviors unpredictably, that is, independent of previous choices and their outcomes. The iterative updating of neural processes involved in selecting actions to produce mixed-strategy behaviors, however, remain poorly understood In both tasks, premotor activity and behavior were shaped by past actions and rewards with more recent events exerting the largest influence. Importantly, these sequential effects were attenuated under strategic conditions suggesting that updating of selection processes is not entirely automatic but can be tailored to different decision-making contexts. Together our results highlight the active role played by the brain in choosing strategic actions. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2009-01-30 17:11:21.002

Patients with Amyotrophic lateral sclerosis (ALS) often experience cognitive impairment that accompanies degeneration of the motor system. A valuable tool for assessing cognitive control over behaviour is the antisaccade task which requires: 1) inhibition of the automatic response to look towards an eccentric visual stimulus (prosaccade) to instead 2) redirect gaze in the opposite direction of the stimulus (antisaccade). Psychometric tests were used to quantify the degree of impairment, while eye tracking, functional magnetic resonance imaging (fMRI) and structural MRI were combined to identify the neural correlates of cognitive impairment in ALS. We predict ALS patients will have executive dysfunction and grey matter loss in executive and oculomotor control areas that will affect antisaccade performance and will alter the corresponding brain activation. ALS patients and age-matched controls participated in a rapid-event-related fMRI design with interleaved pro- and antisaccade trials. Catch trials (no stimulus presented after instructional cue to prepare pro- or antisaccade) allowed us to discern the preparatory period from the execution period. ALS patients were biased towards automatic saccade responses, and had greater difficulty with antisaccades relative to controls in terms of correct and timely responses. We found that worsened antisaccade performance in ALS correlated with the degree of cognitive impairment. Generally, we found trends of increased brain activation during the preparatory period of antisaccades in ALS patients compared to controls in most oculomotor areas; meanwhile few differences were seen during execution. Structural analyses revealed ALS patients had decreased grey matter thickness in frontotemporal and oculomotor regions such as the frontal and supplementary eye fields (FEF, SEF) and the dorsolateral prefrontal cortex (DLPFC). These findings suggest that loss of structural integrity and executive dysfunction may elicit compensation mechanisms to improve functional and behavioural performance. Despite this compensation, ALS patients still performed worse on antisaccades than controls. Further investigation to expand the current data set should improve our ability to assuredly identify the neural correlates of cognitive decline in ALS, and may provide a model system to use for critical evaluation of future therapies and interventions for ALS. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2011-09-22 14:20:39.704

Active movements are a key feature of human behavior. Even when we do not move our limbs we almost never stop guiding our eyes. As a minimal but omnipresent form of behavior, fast eye movements, called saccades, sample the visual world and determine to a large extent what we perceive. Despite being an integral part of visual perception, prevalent research practice treats the human subject as a passive observer who fixates a spot on the screen and is not allowed to move. Yet, learning sensorimotor interactions by active exploration in order to predict future changes and guide actions seems to be a fundamental principle of neural organization. This results in neural patterns of active behavior that can be fundamentally different from the neural processes revealed in movement-restricted laboratory settings questioning the transferability of results from experimental paradigms demanding fixation to real-world free viewing behavior. In this thesis, we aim at studying the neural mechanisms underlying free viewing behavior. In order to assess the fast, flexible and possibly distributed neural dynamics of active vision, we established a procedure for studying eye movements in magnetoencephalography (MEG) and investigated oscillatory signatures associated with sensorimotor processes of eye movements and saccade target selection, two fundamental processes of active vision. Electroencephalography (EEG) and MEG can non-invasively measure fast neural dynamics and hence seem ideally suited for studying active vision in humans. However, artifacts related to eye movements confound both EEG and MEG signals, and a thorough handling of these artifacts is crucial for investigating neural activities during active movements. Mostly, cleaning of ocular artifacts has been performed for occasional eye movements and blinks in fixation paradigms in EEG. Less is known about the impact of ocular artifacts and especially the saccadic spike on MEG. As a first step to enable active vision studies in MEG, we investigated ocular artifacts and possible ways of their separation from neural signals in MEG. We show that the saccadic spike seriously distorts the spatial and spectral characteristics of the MEG signal (Study 2). We further tested if electrooculogram (EOG) based regression is feasible for corneo-retinal artifact removal (Study 1). Due to an often-raised concern, we addressed if EOG regression eliminates neural activity when applied for MEG. Our results do not indicate such susceptibility and we conclude that EOG regression for removing the corneo-retinal artifact in MEG is suitable. Based on insights from both studies, we established an artifact handling procedure including EOG regression and independent component analysis (ICA) to assess the neural dynamics of active vision. In Study 3, we investigated spectral signatures of neuronal activity across cortex underlying saccade preparation, execution and re-fixation in a delayed saccade task. During preparation and execution, we found a dichotomic signature of gamma power increases and beta power decreases in widespread cortical areas related to saccadic control, including fronto-parietal structures. Saccade direction specific signatures resided in hemisphere lateralized changes in low gamma and alpha power in posterior parietal cortex during preparation extending to extrastriate areas during re-fixation. Real-world behavior implies the constant need to flexibly select actions between competing behavioral alternatives depending on both sensory input and internal states. In order to assess internally motivated viewing behavior, we compared neuronal activity of externally cued saccades with saccades to freely chosen, equally valuable targets. We found gamma band specific power increases in fronto-parietal areas that are likely to reflect a fast transient process of action guidance for sensory-guided saccades and a sustained process for internally selecting between competing behavioral alternatives. The sustained signature of internal action selection suggests that a decision between spatially oriented movements is mediated within sensorimotor structures by neural competition between assemblies encoding parallel evolving movement plans. Since our observations support the assumption that a decision emerges through the distributed consensus of neural activities within effector specific areas rather than in a distinct decision module, they argue for the importance of studying mental processes within their ecologically valid and active context. This thesis shows the feasibility of studying neural mechanisms of active vision in MEG and provides important steps for studying neurophysiological correlates of free viewing in the future. The observed spectrally specific, distributed signatures highlight the importance of assessing fast oscillatory dynamics across the cortex for understanding neural mechanisms mediating real-world active behavior.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18124号 / 医博第3844号 / 新制||医||1001(附属図書館) / 30982 / 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 渡邉 大 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM