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https://www.readbyqxmd.com/read/28532350/corollary-discharge-and-oculomotor-proprioception-cortical-mechanisms-for-spatially-accurate-vision
#1
Linus D Sun, Michael E Goldberg
A classic problem in psychology is understanding how the brain creates a stable and accurate representation of space for perception and action despite a constantly moving eye. Two mechanisms have been proposed to solve this problem: Herman von Helmholtz's idea that the brain uses a corollary discharge of the motor command that moves the eye to adjust the visual representation, and Sir Charles Sherrington's idea that the brain measures eye position to calculate a spatial representation. Here, we discuss the cognitive, neuropsychological, and physiological mechanisms that support each of these ideas...
October 14, 2016: Annual Review of Vision Science
https://www.readbyqxmd.com/read/28528360/a-spiking-neural-network-model-of-the-midbrain-superior-colliculus-that-generates-saccadic-motor-commands
#2
Bahadir Kasap, A John van Opstal
Single-unit recordings suggest that the midbrain superior colliculus (SC) acts as an optimal controller for saccadic gaze shifts. The SC is proposed to be the site within the visuomotor system where the nonlinear spatial-to-temporal transformation is carried out: the population encodes the intended saccade vector by its location in the motor map (spatial), and its trajectory and velocity by the distribution of firing rates (temporal). The neurons' burst profiles vary systematically with their anatomical positions and intended saccade vectors, to account for the nonlinear main-sequence kinematics of saccades...
May 20, 2017: Biological Cybernetics
https://www.readbyqxmd.com/read/28525567/saccadic-eye-movements-and-attentional-control-in-alzheimer-s-disease
#3
Nicolas Noiret, Nicolas Carvalho, Éric Laurent, Gilles Chopard, Mickaël Binetruy, Magali Nicolier, Julie Monnin, Eloi Magnin, Pierre Vandel
Objective: Several studies have demonstrated saccadic eye movement (SEM) abnormalities in Alzheimer's disease (AD) when patients performed prosaccade (PS) and antisaccade (AS) tasks. Some studies have also showed that SEM abnormalities were correlated with dementia rating tests such as the Mini Mental State Evaluation (MMSE). Therefore, it has been suggested that SEMs could provide useful information for diagnosis. However, little is known about predictive saccades (PreS)-saccades triggered before or very quickly after stimuli appearance-and their relationships with cognition in AD...
May 19, 2017: Archives of Clinical Neuropsychology: the Official Journal of the National Academy of Neuropsychologists
https://www.readbyqxmd.com/read/28521141/indirect-pathway-of-caudal-basal-ganglia-for-rejection-of-valueless-visual-objects
#4
Hyoung F Kim, Hidetoshi Amita, Okihide Hikosaka
The striatum controls behavior in two ways: facilitation and suppression through the direct and indirect pathways, respectively. However, it is still unclear what information is processed in these pathways. To address this question, we studied two pathways originating from the primate caudate tail (CDt). We found that the CDt innervated the caudal-dorsal-lateral part of the substantia nigra pars reticulata (cdlSNr), directly or indirectly through the caudal-ventral part of the globus pallidus externus (cvGPe)...
May 17, 2017: Neuron
https://www.readbyqxmd.com/read/28520552/prestimulus-inhibition-of-saccades-in-adults-with-and-without-attention-deficit-hyperactivity-disorder-as-an-index-of-temporal-expectations
#5
Yarden Dankner, Lilach Shalev, Marisa Carrasco, Shlomit Yuval-Greenberg
Knowing when to expect important events to occur is critical for preparing context-appropriate behavior. However, anticipation is inherently complicated to assess because conventional measurements of behavior, such as accuracy and reaction time, are available only after the predicted event has occurred. Anticipatory processes, which occur prior to target onset, are typically measured only retrospectively by these methods. In this study, we utilized a novel approach for assessing temporal expectations through the dynamics of prestimulus saccades...
May 1, 2017: Psychological Science
https://www.readbyqxmd.com/read/28515286/responses-of-purkinje-cells-in-the-oculomotor-vermis-of-monkeys-during-smooth-pursuit-eye-movements-and-saccades-comparison-with-floccular-complex
#6
Ramanujan T Raghavan, Stephen G Lisberger
We recorded the responses of Purkinje cells in the oculomotor vermis during smooth pursuit and saccadic eye movements. Our goal was to characterize the responses in the vermis using approaches that would allow direct comparisons with responses of Purkinje cells in another cerebellar area for pursuit, the floccular complex. Simple-spike firing of vermis Purkinje cells is direction selective during both pursuit and saccades, but the preferred directions are sufficiently independent so that downstream circuits could decode signals to drive pursuit and saccades separately...
May 17, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28512444/longitudinal-quantification-of-eye-movement-impairments-after-pontine-hemorrhage
#7
Melis Suner, Glen T Prusky, Jason B Carmel, N Jeremy Hill
INTRODUCTION: We report a case of hypertrophic olivary degeneration due to pontine hemorrhage. A 59-year-old male with untreated hypertension suffered a primary pontine hemorrhage, which caused horizontal eye-movement limitation. Progressive neurological deterioration with involuntary eye and palatal movements began months after hemorrhage. This was accompanied by magnetic resonance imaging evidence of hypertrophic olivary degeneration at 4.5 months. BACKGROUND: Primary pontine hemorrhage often leads to impairment of eye movements and diplopia...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28505662/asymmetries-between-convergence-and-divergence-reveal-tonic-vergence-is-dependent-upon-phasic-vergence-function
#8
Ian M Erkelens, William R Bobier
Horizontal vergence eye movements are controlled by two processes, phasic and slow-tonic. Slow-tonic responses are hypothesized to be stimulated by the faster, pulse-step neural output of the phasic system. This suggests that the general behavior of each system should be similar; however, this relationship has yet to be investigated directly. We characterize the relationship between phasic and tonic vergence by quantifying directional asymmetries in the response properties of each mechanism to the same disparity amplitudes...
May 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28502407/i-spy-with-my-little-eye-analysis-of-airline-pilots-gaze-patterns-in-a-manual-instrument-flight-scenario
#9
Andreas Haslbeck, Bo Zhang
The aim of this study was to analyze pilots' visual scanning in a manual approach and landing scenario. Manual flying skills suffer from increasing use of automation. In addition, predominantly long-haul pilots with only a few opportunities to practice these skills experience this decline. Airline pilots representing different levels of practice (short-haul vs. long-haul) had to perform a manual raw data precision approach while their visual scanning was recorded by an eye-tracking device. The analysis of gaze patterns, which are based on predominant saccades, revealed one main group of saccades among long-haul pilots...
September 2017: Applied Ergonomics
https://www.readbyqxmd.com/read/28501325/a-role-for-nmdar-dependent-cerebellar-plasticity-in-adaptive-control-of-saccades-in-humans
#10
S Colnaghi, P Colagiorgio, M Versino, G Koch, E D'Angelo, S Ramat
BACKGROUND: Saccade pulse amplitude adaptation is mediated by the dorsal cerebellar vermis and fastigial nucleus. Long-term depression at the parallel fibre-Purkinjie cell synapses has been suggested to provide a cellular mechanism for the corresponding learning process. The mechanisms and sites of this plasticity, however, are still debated. OBJECTIVE: To test the role of cerebellar plasticity phenomena on adaptive saccade control. METHODS: We evaluated the effect of continuous theta burst stimulation (cTBS) over the posterior vermis on saccade amplitude adaptation and spontaneous recovery of the initial response...
May 5, 2017: Brain Stimulation
https://www.readbyqxmd.com/read/28499971/selective-reward-affects-the-rate-of-saccade-adaptation
#11
Yoshiko Kojima, Robijanto Soetedjo
In this study we tested whether a selective reward could affect the adaptation of saccadic eye movements in monkeys. We induced the adaptation of saccades by displacing the target of a horizontal saccade vertically as the eye moved toward it, thereby creating an apparent vertical dysmetria. The repeated upward target displacement caused the originally horizontal saccade to gradually deviate upward over the course of several hundred trials. We induced this directional adaptation in both right- and leftward saccades in every experiment (n=20)...
May 10, 2017: Neuroscience
https://www.readbyqxmd.com/read/28495637/veridical-stimulus-localization-is-linked-to-human-area-v5-mt-activity
#12
Anna K Bonkhoff, Eckart Zimmermann, Gereon R Fink
How the brain represents visual space is an unsolved mystery. Spatial localization becomes particularly challenging when visual information processing is briefly disrupted, as in the case of saccadic eye movements, blinks, or visual masks. As we have recently reported, a compression of visual space, illustrated by displacements of shortly flashed stimuli, can be observed in the temporal vicinity of masking stimuli during ocular fixation (Zimmermann et al., 2013). We here aimed at investigating the neural mechanisms underlying these displacements using functional magnetic resonance imaging...
May 8, 2017: NeuroImage
https://www.readbyqxmd.com/read/28487639/reticular-formation-connections-underlying-horizontal-gaze-the-central-mesencephalic-reticular-formation-cmrf-as-a-conduit-for-the-collicular-saccade-signal
#13
Niping Wang, Eddie Perkins, Lan Zhou, Susan Warren, Paul J May
The central mesencephalic reticular formation (cMRF) occupies much of the core of the midbrain tegmentum. Physiological studies indicate that it is involved in controlling gaze changes, particularly horizontal saccades. Anatomically, it receives input from the ipsilateral superior colliculus (SC) and it has downstream projections to the brainstem, including the horizontal gaze center located in the paramedian pontine reticular formation (PPRF). Consequently, it has been hypothesized that the cMRF plays a role in the spatiotemporal transformation needed to convert spatially coded collicular saccade signals into the temporally coded signals utilized by the premotor neurons of the horizontal gaze center...
2017: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/28487376/visual-and-ocular-motor-function-in-the-atypical-form-of-neurodegeneration-with-brain-iron-accumulation-type-i
#14
Joana Jesus-Ribeiro, Cláudia Farinha, Margarida Amorim, Anabela Matos, Aldina Reis, João Lemos, Miguel Castelo-Branco, Cristina Januário
BACKGROUND/AIMS: Neurodegeneration with brain iron accumulation (NBIA) type I is a rare disease that can be divided into a classical or atypical variant, according to age of onset and clinical pattern. Neuro-ophthalmological involvement has been documented in the classical variant but only anecdotically in the atypical variant. We sought to describe the visual and ocular motor function in patients with atypical form of NBIA type I. METHODS: Cross-sectional study, including patients with genetically confirmed NBIA type I and classified as atypical variant, who underwent ophthalmological examination with best corrected visual acuity (BCVA), optical coherence tomography (OCT), fundus autofluorescence (FAF), electroretinography (ERG), visual evoked potentials (VEP) and video-oculography...
May 9, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28486738/-isolated-high-frequency-hvor-lesion-in-patients-with-chronic-dizziness
#15
Roland Hülse, Manfred Hülse, Karl Hörmann, Matthias Hölzl, Richard Birk, Angela Wenzel
In the presented study video-head impulse test (vHIT) was performed in 72 patients with complaints of dizziness for more than 3 months who did not show any pathology in rotatory chair testing or caloric test, in order to analyzed high frequency vestibular-ocular-reflex (VOR). Retrospective data analyzed of rotatory chair testing, caloric tests and vHIT results were accomplished in 72 patients. Gain, gain variance and the occurrence of catch-up saccades were measured. 10 patients (n=10; 13.8%) showed pathologic vHOR results with reduced gain...
May 9, 2017: Laryngo- Rhino- Otologie
https://www.readbyqxmd.com/read/28486116/active-vision-dynamic-reformatting-of-visual-information-by-the-saccade-drift-cycle
#16
Igor Kagan, David C Burr
Visual processing depends on rapid parsing of global features followed by analysis of fine detail. A new study suggests that this transformation is enabled by a cycle of saccades and fixational drifts, which reformat visual input to match the spatiotemporal sensitivity of fast and slow neuronal pathways.
May 8, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28484820/-vertigo-and-dizziness-in-the-emergency-room
#17
REVIEW
A Zwergal, K Möhwald, M Dieterich
Vertigo and dizziness are among the most common chief complaints in the emergency department. Etiologies can be categorized into three subgroups: neurootological (vestibular), medical (especially cardiovascular, metabolic), and psychiatric disorders. The diagnostic approach in the emergency department is based on a systematic analysis of case history (type, time course of symptoms, modulating factors, associated symptoms), clinical examination of the vestibular, ocular motor, and cerebellar systems (head impulse test, nystagmus, skew deviation, positioning maneuver, test of gait and stance), as well as a basal monitoring (vital signs, 12-lead ECG, blood tests)...
May 8, 2017: Der Nervenarzt
https://www.readbyqxmd.com/read/28484381/impaired-activation-of-visual-attention-network-for-motion-salience-is-accompanied-by-reduced-functional-connectivity-between-frontal-eye-fields-and-visual-cortex-in-strabismic-amblyopia
#18
Hao Wang, Sheila G Crewther, Minglong Liang, Robin Laycock, Tao Yu, Bonnie Alexander, David P Crewther, Jian Wang, Zhengqin Yin
Strabismic amblyopia is now acknowledged to be more than a simple loss of acuity and to involve alterations in visually driven attention, though whether this applies to both stimulus-driven and goal-directed attention has not been explored. Hence we investigated monocular threshold performance during a motion salience-driven attention task involving detection of a coherent dot motion target in one of four quadrants in adult controls and those with strabismic amblyopia. Psychophysical motion thresholds were impaired for the strabismic amblyopic eye, requiring longer inspection time and consequently slower target speed for detection compared to the fellow eye or control eyes...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28481032/volitional-saccade-performance-in-a-large-sample-of-patients-with-obsessive-compulsive-disorder-and-unaffected-first-degree-relatives
#19
Katharina Bey, Lisa Kloft, Leonhard Lennertz, Rosa Grützmann, Stephan Heinzel, Christian Kaufmann, Julia Klawohn, Anja Riesel, Inga Meyhöfer, Norbert Kathmann, Michael Wagner
Recent evidence indicates that patients with obsessive-compulsive disorder (OCD) as well as their unaffected first-degree relatives show deficits in the volitional control of saccades, suggesting that volitional saccade performance may constitute an endophenotype of OCD. Here, we aimed to replicate and extend these findings in a large, independent sample. One hundred and fifteen patients with OCD, 103 healthy comparison subjects without a family history of OCD, and 31 unaffected first-degree relatives of OCD patients were examined using structured clinical interviews and performed a volitional saccade task as well as a prosaccade task...
May 8, 2017: Psychophysiology
https://www.readbyqxmd.com/read/28475622/target-distractor-synchrony-affects-performance-in-a-novel-motor-task-for-studying-action-selection
#20
Sebastian James, Olivia A Bell, Muhammed A M Nazli, Rachel E Pearce, Jonathan Spencer, Katie Tyrrell, Phillip J Paine, Timothy J Heaton, Sean Anderson, Mauro Da Lio, Kevin Gurney
The study of action selection in humans can present challenges of task design since our actions are usually defined by many degrees of freedom and therefore occupy a large action-space. While saccadic eye-movement offers a more constrained paradigm for investigating action selection, the study of reach-and-grasp in upper limbs has often been defined by more complex scenarios, not easily interpretable in terms of such selection. Here we present a novel motor behaviour task which addresses this by limiting the action space to a single degree of freedom in which subjects have to track (using a stylus) a vertical coloured target line displayed on a tablet computer, whilst ignoring a similarly oriented distractor line in a different colour...
2017: PloS One
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