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https://www.readbyqxmd.com/read/28728290/-advances-in-research-of-divergence-insufficiency
#1
Y P Li, W Zhang
Divergence insufficiency is acquired esotropia at distance fixation with symptomatic uncrossed diplopia but fusion at near. It can be divided into two forms: primary isolated form and secondary form associated with neurologic abnormalities, also called divergence palsy. The clinical features of divergence insufficiency include small esotropia only at distance but orthotropia or small esophoria at near, comitant deviation at lateral gaze, reduced divergence fusion, full abduction and normal saccadic velocities in abduction...
July 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28720525/motor-resonance-during-action-observation-is-gaze-contingent-a-tms-study
#2
Giorgia D'Innocenzo, Claudia C Gonzalez, Alexander V Nowicky, A Mark Williams, Daniel T Bishop
When we observe others performing an action, visual input to our mirror neuron system is reflected in the facilitation of primary motor cortex (M1), a phenomenon known as 'motor resonance'. However, it is unclear whether this motor resonance is contingent upon our point-of-gaze. In order to address this issue, we collected gaze data from participants as they viewed an intransitive action - thumb abduction/adduction - under four conditions: with natural gaze behaviour (free viewing) and with their gaze fixated on each of three predetermined loci at various distances from the prime mover...
July 15, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28720523/sensory-attenuation-of-self-initiated-sounds-maps-onto-habitual-associations-between-motor-action-and-sound
#3
Nathan G Mifsud, Thomas J Whitford
Sensory attenuation refers to reduced brain responses to self-initiated sensations relative to those produced by the external world, a distinction that is vital for dynamic motor control and our sense of agency. Typically, willed vocalizations elicit larger N1 reduction of the auditory evoked potential compared to indirectly evoked sounds, such as tones generated by button-presses, which is attributed to the prediction and cancellation of incoming signals enabled by speech motor commands. However, physical confounds exist, including different stimuli and the increased motor artefact associated with mouth vs...
July 15, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28715575/saccadic-suppression-during-voluntary-versus-reactive-saccades
#4
Svenja Gremmler, Markus Lappe
Saccades are fast eye movements that reorient gaze. They can be performed voluntarily-for example, when viewing a scene-but they can also be triggered in reaction to suddenly appearing targets. The generation of these voluntary and reactive saccades have been shown to involve partially different cortical pathways. However, saccades of either type confront the visual system with a major challenge from massive image motion on the retina. Despite the fact that the whole scene is swept across the retina, a saccade usually does not elicit a percept of motion...
July 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28714081/combining-two-model-systems-of-psychosis-the-effects-of-schizotypy-and-sleep-deprivation-on-oculomotor-control-and-psychotomimetic-states
#5
Inga Meyhöfer, Maria Steffens, Eliana Faiola, Anna-Maria Kasparbauer, Veena Kumari, Ulrich Ettinger
Model systems of psychosis, such as schizotypy or sleep deprivation, are valuable in informing our understanding of the etiology of the disorder and aiding the development of new treatments. Schizophrenia patients, high schizotypes, and sleep-deprived subjects are known to share deficits in oculomotor biomarkers. Here, we aimed to further validate the schizotypy and sleep deprivation models and investigated, for the first time, their interactive effects on smooth pursuit eye movements (SPEM), prosaccades, antisaccades, predictive saccades, and measures of psychotomimetic states, anxiety, depression, and stress...
July 17, 2017: Psychophysiology
https://www.readbyqxmd.com/read/28709922/pre-and-post-saccadic-stimulus-timing-in-saccadic-suppression-of-displacement-a-computational-model
#6
Arnold Ziesche, Julia Bergelt, Heiner Deubel, Fred H Hamker
When the target of a saccadic eye movement is displaced while the eyes move this displacement is often not noticed (saccadic suppression of displacement, SSD). We present a neurobiologically motivated, computational model of SSD and compare its simulation results to experimental data. The model offers a simple explanation of the effects of pre- and post-saccadic stimulus blanking on SSD in terms of peri-saccadic network dynamics. Under normal peri-saccadic conditions pre-and post-saccadic stimulus traces are recurrently integrated with reference to present and future eye position, whereas blanking diminishes the pre-saccadic stimulus trace and thus leads to an uninfluenced integration of the post-saccadic stimulus trace...
July 11, 2017: Vision Research
https://www.readbyqxmd.com/read/28704206/an-autonomous-robot-inspired-by-insect-neurophysiology-pursues-moving-features-in-natural-environments
#7
Zahra M Bagheri, Benjamin S Cazzolato, Steven Grainger, David C O'Carroll, Steven D Wiederman
OBJECTIVE: Many computer vision and robotic applications require the implementation of robust and efficient target-tracking algorithms on a moving platform. However, deployment of a real-time system is challenging, even with the computational power of modern hardware. Lightweight and low-powered flying insects, such as dragonflies, track prey or conspecifics within cluttered natural environments, illustrating an efficient biological solution to the target-tracking problem. APPROACH: We used our recent recordings from 'small target motion detector' neurons in the dragonfly brain to inspire the development of a closed-loop target detection and tracking algorithm...
July 13, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28701549/altered-visual-strategies-and-attention-are-related-to-increased-force-fluctuations-during-a-pinch-grip-task-in-older-adults
#8
Kevin G Keenan, Wendy E Huddleston, Bradley E Ernest
The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 years) were monitored during a low-force pinch grip task while viewing three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured...
July 12, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28700673/the-trickle-down-effect-of-predictability-secondary-task-performance-benefits-from-predictability-in-the-primary-task
#9
Magdalena Ewa Król, Michał Król
Predictions optimize processing by reducing attentional resources allocation to expected or predictable sensory data. Our study demonstrates that these saved processing resources can be then used on concurrent stimuli, and in consequence improve their processing and encoding. We illustrate this "trickle-down" effect with a dual task, where the primary task varied in terms of predictability. The primary task involved detection of a pre-specified symbol that appeared at some point of a short video of a dot moving along a random, semi-predictable or predictable trajectory...
2017: PloS One
https://www.readbyqxmd.com/read/28698242/abnormal-fixational-eye-movements-in-strabismus
#10
Fatema F Ghasia, Jorge Otero-Millan, Aasef G Shaikh
INTRODUCTION: Fixational saccades are miniature eye movements that constantly change the gaze during attempted visual fixation. Visually guided saccades and fixational saccades represent an oculomotor continuum and are produced by common neural machinery. Patients with strabismus have disconjugate binocular horizontal saccades. We examined the stability and variability of eye position during fixation in patients with strabismus and correlated the severity of fixational instability with strabismus angle and binocular vision...
July 11, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28695758/differential-vergence-movements-in-reading-chinese-and-english-greater-fixation-initial-binocular-disparity-is-advantageous-in-reading-the-denser-orthography
#11
Yi-Ting Hsiao, Richard Shillcock, Mateo Obregón, Hamutal Kreiner, Matthew A J Roberts, Scott McDonald
We explore two aspects of exovergence: we test whether smaller binocular fixation disparities accompany the shorter saccades and longer fixations observed in reading Chinese; we test whether potentially advantageous psychophysical effects of exovergence (cf. Arnold & Schindel, 2010; Kersten & Murray, 2010) transfer to text reading. We report differential exovergence in reading Chinese and English: Chinese readers begin fixations with more binocular disparity, but end fixations with a disparity closely similar to that of the English readers...
July 11, 2017: Quarterly Journal of Experimental Psychology: QJEP
https://www.readbyqxmd.com/read/28690585/saccadic-impairments-in-patients-with-the-norrbottnian-form-of-gaucher-s-disease-type-3
#12
Josefine Blume, Stanislav Beniaminov, Cecilia Kämpe Björkvall, Maciej Machaczka, Per Svenningsson
BACKGROUND: Chronic neuronopathic Gaucher's disease type 3 (GD3) is relatively frequent in northern Sweden. Besides multiple other neurological symptoms, horizontal gaze palsy or oculomotor apraxia is common in GD3. OBJECTIVE: To characterize the saccades in patients with Norrbottnian GD3 with respect to their neurological and cognitive status using a computer-based eye-tracking technique. METHODS: Horizontal and vertical reflexive saccades as well as antisaccades of nine GD3 patients [4M/5F; 41...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28690501/cortical-activation-during-landmark-centered-vs-gaze-centered-memory-of-saccade-targets-in-the-human-an-fmri-study
#13
Ying Chen, J D Crawford
A remembered saccade target could be encoded in egocentric coordinates such as gaze-centered, or relative to some external allocentric landmark that is independent of the target or gaze (landmark-centered). In comparison to egocentric mechanisms, very little is known about such a landmark-centered representation. Here, we used an event-related fMRI design to identify brain areas supporting these two types of spatial coding (i.e., landmark-centered vs. gaze-centered) for target memory during the Delay phase where only target location, not saccade direction, was specified...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28689088/looking-for-ideas-eye-behavior-during-goal-directed-internally-focused-cognition
#14
Sonja Walcher, Christof Körner, Mathias Benedek
Humans have a highly developed visual system, yet we spend a high proportion of our time awake ignoring the visual world and attending to our own thoughts. The present study examined eye movement characteristics of goal-directed internally focused cognition. Deliberate internally focused cognition was induced by an idea generation task. A letter-by-letter reading task served as external task. Idea generation (vs. reading) was associated with more and longer blinks and fewer microsaccades indicating an attenuation of visual input...
July 6, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28688606/a-clinical-and-neurophysiological-motor-signature-of-unverricht-lundborg-disease
#15
E Hainque, A Blancher, V Mesnage, S Rivaud-Pechoux, A Bertrand, S Dupont, V Navarro, E Roze, I Gourfinkel-An, E Apartis
OBJECTIVES: Unverricht-Lundborg disease (ULD) is the most common form of progressive myoclonus epilepsy. Cerebellar dysfunction may appear over time, contributing along with myoclonus to motor disability. The purpose of the present work was to clarify the motor and neurophysiological characteristics of ULD patients. METHODS: Nine patients with genetically proven ULD were evaluated clinically (medical history collected from patient charts, the Scale for the Assessment and Rating of Ataxia and Unified Myoclonus Rating Scale)...
July 5, 2017: Revue Neurologique
https://www.readbyqxmd.com/read/28685486/conditional-control-in-visual-selection
#16
REVIEW
Wieske van Zoest, Stefan Van der Stigchel, Mieke Donk
Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye movements and attention and to outline the conditions that help determine control. Evidence suggests that the ability to establish control depends on the complexity of the display as well as the point in time at which selection occurs...
July 6, 2017: Attention, Perception & Psychophysics
https://www.readbyqxmd.com/read/28683455/binocular-fixation-reduces-fixational-eye-movements-in-the-worst-eye-of-patients-with-center-involving-diabetic-macular-edema
#17
Nanna Stæhr Jakobsen, Dorte Ancher Larsen, Toke Bek
PURPOSE: Treatment of diabetic maculopathy with vascular endothelial growth factor inhibitors is in some patients ineffective, and, therefore, parameters predicting visual outcome after treatment should be identified. It has been shown that fixational saccades are increased in patients with reduced visual acuity secondary to diabetic maculopathy, but it is unknown to what extent these saccades in an eye affected by diabetic maculopathy are influenced by the other eye during binocular fixation...
July 7, 2017: Ophthalmic Research
https://www.readbyqxmd.com/read/28682255/visual-attention-saccadic-models-learn-to-emulate-gaze-patterns-from-childhood-to-adulthood
#18
Olivier Le Meur, Antoine Coutrot, Zhi Liu, Pia Rama, Adrien Le Roch, Andrea Helo
How people look at visual information reveals fundamental information about themselves, their interests and their state of mind. While previous visual attention models output static 2D saliency maps, saccadic models aim to predict not only where observers look at but also how they move their eyes to explore the scene. In this paper, we demonstrate that saccadic models are a flexible framework that can be tailored to emulate observer's viewing tendencies. More specifically, we use fixation data from 101 observers split into five age groups (adults, 8-10 y...
October 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28682097/saccadic-reaction-times-in-infants-and-adults-spatiotemporal-factors-gender-and-interlaboratory-variation
#19
Ben Kenward, Felix-Sebastian Koch, Linda Forssman, Julia Brehm, Ida Tidemann, Annette Sundqvist, Carin Marciszko, Tone Kristine Hermansen, Mikael Heimann, Gustaf Gredebäck
Saccade latency is widely used across infant psychology to investigate infants' understanding of events. Interpreting particular latency values requires knowledge of standard saccadic RTs, but there is no consensus as to typical values. This study provides standard estimates of infants' (n = 194, ages 9 to 15 months) saccadic RTs under a range of different spatiotemporal conditions. To investigate the reliability of such standard estimates, data is collected at 4 laboratories in 3 countries. Results indicate that reactions to the appearance of a new object are much faster than reactions to the deflection of a currently fixated moving object; upward saccades are slower than downward or horizontal saccades; reactions to more peripheral stimuli are much slower; and this slowdown is greater for boys than girls...
July 6, 2017: Developmental Psychology
https://www.readbyqxmd.com/read/28679840/contrasting-speed-accuracy-trade-offs-for-eye-and-hand-movements-reveal-the-optimal-nature-of-saccade-kinematics
#20
Atul Gopal P A, Sumitash Jana, Aditya Murthy
In contrast to hand movements, the existence of a neural representation of saccade kinematics is unclear. Saccades kinematics is typically thought to be specified by motor error/desired displacement and generated by brain stem circuits that are not penetrable to voluntary control. We studied the influence of instructed hand movement velocity on the kinematics of saccades executed without explicit instructions. When the hand movement was slow the saccade velocity decreased, independent of saccade amplitude. We leveraged the modulation of saccade velocity to study the optimality of saccades (in terms of velocity and end-point accuracy) in relation to the well-known speed-accuracy trade-off that governs voluntary movements (Fitts' law)...
July 5, 2017: Journal of Neurophysiology
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