The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
Peter Thier - One of the best experts on this subject based on the ideXlab platform.
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v1 neurons encode the perceptual compensation of false torsion arising from Listings Law
bioRxiv, 2018Co-Authors: Mohammad Farhan Khazali, Peter ThierAbstract:We try to deploy the retinal fovea to optimally scrutinize an object of interest by directing our eyes to it. Horizontal and vertical components of these fixation eye movements are determined by the objects location. However, fixation eye movements also involve a torsional component, which according to Listings Law is fully determined by the 2D eye position acquired. According to Von Helmholtz knowledge of the torsion provided by this Law alleviates the perceptual interpretation of the image tilt that changes with fixation, a view supported by psychophysical experiments he pioneered. We address the question where and how Listings Law is implemented in the visual system and we show that neurons in monkey area V1 use knowledge of torsion to compensate the image tilt associated with specific eye positions as set by Listings Law.
Mohammad Farhan Khazali - One of the best experts on this subject based on the ideXlab platform.
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v1 neurons encode the perceptual compensation of false torsion arising from Listings Law
bioRxiv, 2018Co-Authors: Mohammad Farhan Khazali, Peter ThierAbstract:We try to deploy the retinal fovea to optimally scrutinize an object of interest by directing our eyes to it. Horizontal and vertical components of these fixation eye movements are determined by the objects location. However, fixation eye movements also involve a torsional component, which according to Listings Law is fully determined by the 2D eye position acquired. According to Von Helmholtz knowledge of the torsion provided by this Law alleviates the perceptual interpretation of the image tilt that changes with fixation, a view supported by psychophysical experiments he pioneered. We address the question where and how Listings Law is implemented in the visual system and we show that neurons in monkey area V1 use knowledge of torsion to compensate the image tilt associated with specific eye positions as set by Listings Law.
P. Bruno - One of the best experts on this subject based on the ideXlab platform.
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Torsion during saccades between tertiary positions
2016Co-Authors: A. V. Van Berg, P. BrunoAbstract:Abstract We systematically studied the effect of saccade direction and saccade starting position on the velocity profile of the saccade. Saccades were made between tar-gets placed at optical infinity by dichoptic presentation. This arrangement was chosen to evoke conjugate eye movements. Eye movements were recorded binocularly, including torsion. Horizontal and vertical movements of the eyes are strongly correlated (r> 0.95) during the sac-cade, torsional movements are much less so (r. 0.67). Listings Law would predict that the three-dimensional versional velocity of the eye would be located in a plane that is tilted out of Listings plane by an amount that de-pends on the saccades starting position (half angle rule). Taking together all saccades that started from the same initial position a plane could be fitted through the velocity vectors. However, this plane was tilted less relative to Listings plane than predicted by the half angle rule. The deviation was especially large for the yaw component of the tilt (56 % of predicted). For the pitch component the prediction was better (81 % of predicted). In addition, we find that the torsional velocity during the fast “intrasac-cadic ” part of the motion can be unequal in the two eyes. The implications for three-dimensional models of saccad-ic control are discussed. Key words Ocular torsion · Angular velocity · Saccades · Version · Velocity plane
Head-free Gaze-shift - One of the best experts on this subject based on the ideXlab platform.
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POSTER PRESENTATION Open Access Theoretical understanding of three-dimensional,
2016Co-Authors: Head-free Gaze-shiftAbstract:Shifting the line of sight is naturally accomplished by the movements of both eye and head. We are studying the oclumotor system responsible for planning such head-free gaze-shifts. This includes not only the study of the kinematic mechanisms for coordination of eye and head in three-dimensional space, but also an inquiry into the nature of the internal representations that underlie the observed behavior. The latter is believed to be based on neural representations of sensory signals, coding information is receptors ’ frame of reference, being transformed into representations of motor com-mands, coding information in effectors ’ reference frame. At the behavioral level, we propose a kinematic model which gets retinal error and initial eye and head orienta-tions as input and describes an experimentally-inspired sequence of rotations including saccadic eye movement, head movement and vestibule-ocular reflex (VOR). Experimentally observed constraints, Listings ’ Law fo
A. V. Van Berg - One of the best experts on this subject based on the ideXlab platform.
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Torsion during saccades between tertiary positions
2016Co-Authors: A. V. Van Berg, P. BrunoAbstract:Abstract We systematically studied the effect of saccade direction and saccade starting position on the velocity profile of the saccade. Saccades were made between tar-gets placed at optical infinity by dichoptic presentation. This arrangement was chosen to evoke conjugate eye movements. Eye movements were recorded binocularly, including torsion. Horizontal and vertical movements of the eyes are strongly correlated (r> 0.95) during the sac-cade, torsional movements are much less so (r. 0.67). Listings Law would predict that the three-dimensional versional velocity of the eye would be located in a plane that is tilted out of Listings plane by an amount that de-pends on the saccades starting position (half angle rule). Taking together all saccades that started from the same initial position a plane could be fitted through the velocity vectors. However, this plane was tilted less relative to Listings plane than predicted by the half angle rule. The deviation was especially large for the yaw component of the tilt (56 % of predicted). For the pitch component the prediction was better (81 % of predicted). In addition, we find that the torsional velocity during the fast “intrasac-cadic ” part of the motion can be unequal in the two eyes. The implications for three-dimensional models of saccad-ic control are discussed. Key words Ocular torsion · Angular velocity · Saccades · Version · Velocity plane