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https://www.readbyqxmd.com/read/28943085/drosophila-spatiotemporally-integrates-visual-signals-to-control-saccades
#1
Jean-Michel Mongeau, Mark A Frye
Like many visually active animals, including humans, flies generate both smooth and rapid saccadic movements to stabilize their gaze. How rapid body saccades and smooth movement interact for simultaneous object pursuit and gaze stabilization is not understood. We directly observed these interactions in magnetically tethered Drosophila free to rotate about the yaw axis. A moving bar elicited sustained bouts of saccades following the bar, with surprisingly little smooth movement. By contrast, a moving panorama elicited robust smooth movement interspersed with occasional optomotor saccades...
September 15, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28942125/spatio-temporal-dynamics-of-action-effect-associations-in-oculomotor-control
#2
Eva Riechelmann, Aleksandra Pieczykolan, Gernot Horstmann, Arvid Herwig, Lynn Huestegge
While there is ample evidence that actions are guided by anticipating their effects (ideomotor control) in the manual domain, much less is known about the underlying characteristics and dynamics of effect-based oculomotor control. Here, we address three open issues. 1) Is action-effect anticipation in oculomotor control reflected in corresponding spatial saccade characteristics in inanimate environments? 2) Does the previously reported dependency of action latency on the temporal effect delay (action-effect interval) also occur in the oculomotor domain? 3) Which temporal effect delay is optimally suited to develop strong action-effect associations over time in the oculomotor domain? Participants executed left or right free-choice saccades to peripheral traffic lights, causing an (immediate or delayed) action-contingent light switch in the upper vs...
September 20, 2017: Acta Psychologica
https://www.readbyqxmd.com/read/28936361/relationships-between-eye-movements-during-sentence-reading-comprehension-word-spelling-and-reading-and-dti-and-fmri-connectivity-in-students-with-and-without-dysgraphia-or-dyslexia
#3
Kevin Yagle, Todd Richards, Katie Askren, Zoe Mestre, Scott Beers, Robert Abbott, William Nagy, Peter Boord, Virginia Berninger
While eye movements were recorded and brains scanned, 29 children with and without specific learning disabilities (SLDs) decided if sentences they read (half with only correctly spelled words and half with homonym foils) were meaningful. Significant main effects were found for diagnostic groups (non-SLD control, dysgraphia control, and dyslexia) in total fixation (dwell) time, total number of fixations, and total regressions in during saccades; the dyslexia group had longer and more fixations and made more regressions in during saccades than either control group...
January 2017: Journal of Systems and Integrative Neuroscience
https://www.readbyqxmd.com/read/28935857/sensorimotor-computation-underlying-phototaxis-in-zebrafish
#4
Sébastien Wolf, Alexis M Dubreuil, Tommaso Bertoni, Urs Lucas Böhm, Volker Bormuth, Raphaël Candelier, Sophia Karpenko, David G C Hildebrand, Isaac H Bianco, Rémi Monasson, Georges Debrégeas
Animals continuously gather sensory cues to move towards favourable environments. Efficient goal-directed navigation requires sensory perception and motor commands to be intertwined in a feedback loop, yet the neural substrate underlying this sensorimotor task in the vertebrate brain remains elusive. Here, we combine virtual-reality behavioural assays, volumetric calcium imaging, optogenetic stimulation and circuit modelling to reveal the neural mechanisms through which a zebrafish performs phototaxis, i.e...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28934359/microsaccades-during-reading
#5
Norick R Bowers, Martina Poletti
Recent research has shown that microsaccades contribute to high acuity vision. However, little is known about whether microsaccades also play a role in daily activities, such as reading, that do not involve stimuli at the limit of spatial resolution. While the functions of larger saccades in reading have been extensively examined, microsaccades are commonly regarded as oculomotor noise in this context. We used high-resolution eyetracking and precise gaze localization to investigate fine oculomotor behavior during reading...
2017: PloS One
https://www.readbyqxmd.com/read/28931609/movement-related-activity-in-the-periarcuate-cortex-of-monkeys-during-coordinated-eye-and-hand-movements
#6
Kiyoshi Kurata
To determine the role of the periarcuate cortex during coordinated eye and hand movements in monkeys, the present study examined neuronal activity in this region during movement with the hand, eyes, or both as effectors toward a visuospatial target. Similar to the primary motor cortex (M1), the dorsal premotor cortex contained a higher proportion of neurons that were closely related to hand movements, whereas saccade-related neurons were frequently recorded from the frontal eye field (FEF). Interestingly, neurons that exhibited activity related to both eye and hand movements were recorded most frequently in the ventral premotor cortex (PMv), located between the FEF and M1...
September 20, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28924105/the-successful-application-of-plasmapheresis-in-the-treatment-of-a-patient-with-opsoclonus-and-autoantibodies-to-glutamate-receptor-%C3%AE-2
#7
Kiyotaka Nakamagoe, Seitaro Nohara, Yukitoshi Takahashi, Mao Takiguchi, Rio Kawakami, Tadachika Koganezawa, Akira Tamaoka
Glutamate receptor δ2 (GluRδ2) is expressed in the neuronal postsynaptic densities at the junctions between the Purkinje cells and the parallel fibers. Recent reports have described patients with opsoclonus who possess anti-GluRδ2 antibodies. We report the case of a 53-year-old man with opsoclonus whose cerebrospinal fluid was positive for anti-GluRδ2 antibodies. Electronystagmography revealed abnormal sinusoidal eye movements, which were definitively identified as opsoclonus. The frequency and amplitude of saccadic oscillations diminished after plasmapheresis (PE)...
September 15, 2017: Internal Medicine
https://www.readbyqxmd.com/read/28922090/microsaccades-and-interest-areas-during-free-viewing-sport-task
#8
Alessandro Piras, Milena Raffi, Monica Perazzolo, Ivan Malagoli Lanzoni, Salvatore Squatrito
Microsaccades are important fixation eye movements for visual scene perception. Compared to novices, athletes make fewer fixations of longer duration toward limited interest areas crucial for action prediction. Thus, our aim was to study the microsaccade features during those fixations. Gaze behaviour of expert and novice table tennis players was recorder during a task in which subjects were instructed to predict the direction of the ball after the opponent's throw. Three interest areas from the opponent's body and one from the ball trajectory were identified...
September 18, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28913514/the-incidence-of-needle-stick-and-sharp-injuries-and-their-associations-with-visual-function-among-hospital-nurses
#9
Mohammad Ghasemi, Mehdi Khabazkhoob, Hassan Hashemi, Abbasali Yekta, Payam Nabovati
PURPOSE: To determine the one-year incidence of needle stick and sharp injuries (NSIs and SIs) and their associations with visual function among Iranian nurses. METHODS: In this cross-sectional study, 278 nurses working at one hospital were selected through stratified random sampling. After applying the exclusion criteria, the final analysis was performed on the data of 267 nurses. The data of occupational injuries were collected through a researcher-administered questionnaire...
September 2017: Journal of Current Ophthalmology
https://www.readbyqxmd.com/read/28912699/effects-of-scene-properties-and-emotional-valence-on-brain-activations-a-fixation-related-fmri-study
#10
Michał Kuniecki, Kinga B Wołoszyn, Aleksandra Domagalik, Joanna Pilarczyk
Temporal and spatial characteristics of fixations are affected by image properties, including high-level scene characteristics, such as object-background composition, and low-level physical characteristics, such as image clarity. The influence of these factors is modulated by the emotional content of an image. Here, we aimed to establish whether brain correlates of fixations reflect these modulatory effects. To this end, we simultaneously scanned participants and measured their eye movements, while presenting negative and neutral images in various image clarity conditions, with controlled object-background composition...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28904108/comparison-of-three-models-of-saccade-disconjugacy-in-strabismus
#11
Mark M G Walton, Michael J Mustari
In pattern strabismus the horizontal and vertical misalignments vary with eye position along the orthogonal axis. The disorder is typically described in terms of overaction or underaction of oblique muscles. Recent behavioral studies in humans and monkeys, however, have reported that such actions are insufficient to fully explain the patterns of directional and amplitude disconjugacy of saccades. There is mounting evidence that the oculomotor abnormalities associated with strabismus are at least partially attributable to neurophysiological abnormalities...
September 13, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28904104/the-superior-colliculus-and-the-steering-of-saccades-toward-a-moving-visual-target
#12
Laurent Goffart, Aaron Lee Cecala, Neeraj J Gandhi
Following the suggestion that a command encoding the current target location feeds the oculomotor system during interceptive saccades, we tested the involvement of the deep superior colliculus (dSC). Extracellular activity of 52 saccade-related neurons was recorded in three monkeys while they generated saccades to targets that were static or moving along the preferred axis, away from (outward) or toward a fixated target (inward) with a constant speed (20°/s). Vertical and horizontal motions were tested when possible...
September 13, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28900577/comparison-of-threshold-saccadic-vector-optokinetic-perimetry-svop-and-standard-automated-perimetry-sap-in-glaucoma-part-ii-patterns-of-visual-field-loss-and-acceptability
#13
Alice D McTrusty, Lorraine A Cameron, Antonios Perperidis, Harry M Brash, Andrew J Tatham, Pankaj K Agarwal, Ian C Murray, Brian W Fleck, Robert A Minns
PURPOSE: We compared patterns of visual field loss detected by standard automated perimetry (SAP) to saccadic vector optokinetic perimetry (SVOP) and examined patient perceptions of each test. METHODS: A cross-sectional study was done of 58 healthy subjects and 103 with glaucoma who were tested using SAP and two versions of SVOP (v1 and v2). Visual fields from both devices were categorized by masked graders as: 0, normal; 1, paracentral defect; 2, nasal step; 3, arcuate defect; 4, altitudinal; 5, biarcuate; and 6, end-stage field loss...
September 2017: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/28900576/comparison-of-saccadic-vector-optokinetic-perimetry-and-standard-automated-perimetry-in-glaucoma-part-i-threshold-values-and-repeatability
#14
Ian C Murray, Antonios Perperidis, Lorraine A Cameron, Alice D McTrusty, Harry M Brash, Andrew J Tatham, Pankaj K Agarwal, Brian W Fleck, Robert A Minns
PURPOSE: We evaluated threshold saccadic vector optokinetic perimetry (SVOP) and compared results to standard automated perimetry (SAP). METHODS: A cross-sectional study was done including 162 subjects (103 with glaucoma and 59 healthy subjects) recruited at a university hospital. All subjects underwent SAP and threshold SVOP. SVOP uses an eye tracker to monitor eye movement responses to stimuli and determines if stimuli have been perceived based on the vector of the gaze response...
September 2017: Translational Vision Science & Technology
https://www.readbyqxmd.com/read/28900172/cultural-and-developmental-influences-on-overt-visual-attention-to-videos
#15
Omid Kardan, Laura Shneidman, Sheila Krogh-Jespersen, Suzanne Gaskins, Marc G Berman, Amanda Woodward
Top-down influences on observers' overt attention and how they interact with the features of the visual environment have been extensively investigated, but the cultural and developmental aspects of these modulations have been understudied. In this study we investigated these effects for US and Yucatec Mayan infants, children, and adults. Mayan and US participants viewed videos of two actors performing daily Mayan and US tasks in the foreground and the background while their eyes were tracked. Our region of interest analysis showed that viewers from the US looked significantly less at the foreground activity and spent more time attending to the 'contextual' information (static background) compared to Mayans...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28891467/removal-of-inhibition-uncovers-latent-movement-potential-during-preparation
#16
Uday K Jagadisan, Neeraj J Gandhi
The motor system prepares for movements well in advance of their execution. In the gaze control system, the dynamics of preparatory neural activity have been well described by stochastic accumulation-to-threshold models. However, it is unclear whether this activity has features indicative of a hidden movement command. We explicitly tested whether preparatory neural activity in premotor neurons of the primate superior colliculus has "motor potential". We removed downstream inhibition on the saccadic system using the trigeminal blink reflex, triggering saccades at earlier-than-normal latencies...
September 11, 2017: ELife
https://www.readbyqxmd.com/read/28890683/rapid-processing-of-a-global-feature-in-the-on-visual-pathways-of-behaving-monkeys
#17
Jun Huang, Yan Yang, Ke Zhou, Xudong Zhao, Quan Zhou, Hong Zhu, Yingshan Yang, Chunming Zhang, Yifeng Zhou, Wu Zhou
Visual objects are recognized by their features. Whereas, some features are based on simple components (i.e., local features, such as orientation of line segments), some features are based on the whole object (i.e., global features, such as an object having a hole in it). Over the past five decades, behavioral, physiological, anatomical, and computational studies have established a general model of vision, which starts from extracting local features in the lower visual pathways followed by a feature integration process that extracts global features in the higher visual pathways...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28879396/vestibulo-ocular-reflex-deficits-with-medial-longitudinal-fasciculus-lesions
#18
Swee T Aw, Luke Chen, Michael J Todd, Michael H Barnett, G Michael Halmagyi
The medial longitudinal fasciculus (MLF) is the final common pathway for all conjugate adducting horizontal eye movements, as well as for the vertical-torsional vestibulo-ocular reflex (VOR). MLF lesion causes adduction paresis of ipsilesional (adducting) eye with dissociated nystagmus of contralesional (abducting) eye-the well-known clinical syndrome of internuclear ophthalmoplegia (INO). We measured the VOR stimulation and also any catch-up saccades, from individual semicircular canal (SCC) evoked by the head impulse test (HIT), using head and binocular 3-dimensional scleral search coils in 27 multiple sclerosis (MS) patients, 8 with unilateral, 19 with bilateral INO...
September 6, 2017: Journal of Neurology
https://www.readbyqxmd.com/read/28878733/clinical-approach-to-supranuclear-brainstem-saccadic-gaze-palsies
#19
REVIEW
Alexandra Lloyd-Smith Sequeira, John-Ross Rizzo, Janet C Rucker
Failure of brainstem supranuclear centers for saccadic eye movements results in the clinical presence of a brainstem-mediated supranuclear saccadic gaze palsy (SGP), which is manifested as slowing of saccades with or without range of motion limitation of eye movements and as loss of quick phases of optokinetic nystagmus. Limitation in the range of motion of eye movements is typically worse with saccades than with smooth pursuit and is overcome with vestibular-ocular reflexive eye movements. The differential diagnosis of SGPs is broad, although acute-onset SGP is most often from brainstem infarction and chronic vertical SGP is most commonly caused by the neurodegenerative condition progressive supranuclear palsy...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28870284/microsaccadic-sampling-of-moving-image-information-provides-drosophila-hyperacute-vision
#20
Mikko Juusola, An Dau, Zhuoyi Song, Narendra Solanki, Diana Rien, David Jaciuch, Sidhartha Anil Dongre, Florence Blanchard, Gonzalo G de Polavieja, Roger C Hardie, Jouni Takalo
Small fly eyes should not see fine image details. Because flies exhibit saccadic visual behaviors and their compound eyes have relatively few ommatidia (sampling points), their photoreceptors would be expected to generate blurry and coarse retinal images of the world. Here we demonstrate that Drosophila see the world far better than predicted from the classic theories. By using electrophysiological, optical and behavioral assays, we found that R1-R6 photoreceptors' encoding capacity in time is maximized to fast high-contrast bursts, which resemble their light input during saccadic behaviors...
September 5, 2017: ELife
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