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Research paper thumbnail of The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, Jun 1, 2009

Research paper thumbnail of The main sequence of human optokinetic nystagmus

Journal of Vision, Mar 23, 2010

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Vision Research, Mar 1, 2007

We investigated localization of brief visual targets during reXexive eye movements (optokinetic n... more We investigated localization of brief visual targets during reXexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization diVers markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reXexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre-and post-saccadic scenes.

Research paper thumbnail of Systematic deviation of eye-movement direction from stimulus-direction during Optokinetic Nystagmus

Journal of Vision, Jul 25, 2013

Research paper thumbnail of Visual selectivity for heading in the macaque ventral intraparietal area

Journal of neurophysiology, Jan 15, 2014

The patterns of optic flow seen during self-motion can be used to determine the direction of one&... more The patterns of optic flow seen during self-motion can be used to determine the direction of one's own heading. Tracking eye movements which typically occur during everyday life alter this task since they add further retinal image motion and (predictably) distort the retinal flow pattern. Humans employ both visual and nonvisual (extraretinal) information to solve a heading task in such case. Likewise, it has been shown that neurons in the monkey medial superior temporal area (area MST) use both signals during the processing of self-motion information. In this article we report that neurons in the macaque ventral intraparietal area (area VIP) use visual information derived from the distorted flow patterns to encode heading during (simulated) eye movements. We recorded responses of VIP neurons to simple radial flow fields and to distorted flow fields that simulated self-motion plus eye movements. In 59% of the cases, cell responses compensated for the distortion and kept the same ...

Research paper thumbnail of The main sequence of human optokinetic nystagmus

Research paper thumbnail of Systematic deviation of eye-movement direction from stimulus-direction during Optokinetic Nystagmus

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Journal of Vision, 2010

ABSTRACT We investigated localization of brief visual targets during reflexive eye movements (opt... more ABSTRACT We investigated localization of brief visual targets during reflexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization differs markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reflexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre- and post-saccadic scenes.

Research paper thumbnail of Task influences on the dynamic properties of fast eye movements

Journal of Vision, 2009

It is widely debated whether fast phases of the reflexive optokinetic nystagmus (OKN) share prope... more It is widely debated whether fast phases of the reflexive optokinetic nystagmus (OKN) share properties with another class of fast eye movements, visually guided saccades. Conclusions drawn from previous studies were complicated by the fact that a subject's task influences the exact type of OKN: stare vs. look nystagmus. With our current study we set out to determine in the same subjects the exact dynamic properties (main sequence) of various forms of fast eye movements. We recorded fast phases of look and stare nystagmus as well as visually guided saccades. Our data clearly show that fast phases of look and stare nystagmus differ with respect to their main sequence. Fast phases of stare nystagmus were characterized by their lower peak velocities and longer durations as compared to fast phases of look nystagmus. Furthermore we found no differences between fast phases of stare nystagmus evoked with limited and unlimited dot lifetimes. Visually guided saccades were on the same main sequence as fast phases of look nystagmus, while they had higher peak velocities and shorter durations than fast phases of stare nystagmus. Our data underline the critical role of behavioral tasks (e.g., reflexive vs. intentional) for the exact spatiotemporal characteristics of fast eye movements.

Research paper thumbnail of Expansion of Visual Space During Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, 2008

The mechanisms underlying visual perceptual stability are usually investigated using voluntary ey... more The mechanisms underlying visual perceptual stability are usually investigated using voluntary eye movements. In such studies, errors in perceptual stability during saccades and pursuit are commonly interpreted as mismatches between actual eye position and eye-position signals in the brain. The generality of this interpretation could in principle be tested by investigating spatial localization during reflexive eye movements whose kinematics are very similar to those of voluntary eye movements. Accordingly, in this study, we determined mislocalization of flashed visual targets during optokinetic afternystagmus (OKAN). These eye movements are quite unique in that they occur in complete darkness and are generated by subcortical control mechanisms. We found that during horizontal OKAN slow phases, subjects mislocalize targets away from the fovea in the horizontal direction. This corresponds to a perceived expansion of visual space and is unlike mislocalization found for any other volunt...

Research paper thumbnail of The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, 2009

Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmu... more Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN), are coded by only partially overlapping neural networks. This is a likely cause for the differences that have been reported for the dynamic parameters of fast eye movements. The dependence of two of these parameters—peak velocity and duration—on saccadic amplitude has been termed “main sequence.” The main sequence of OKAN fast phases has not yet been analyzed. These eye movements are unique in that they are generated by purely subcortical control mechanisms and that they occur in complete darkness. In this study, we recorded fast phases of OKAN and OKN as well as visually guided and spontaneous saccades under identical background conditions because background characteristics have been reported to influence the main sequence of saccades. Our data clearly show that fast phases of OKAN and OKN differ with respect to their main sequence. OKAN fa...

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Vision Research, 2007

We investigated localization of brief visual targets during reXexive eye movements (optokinetic n... more We investigated localization of brief visual targets during reXexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization diVers markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reXexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre-and post-saccadic scenes.

Research paper thumbnail of The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, Jun 1, 2009

Research paper thumbnail of The main sequence of human optokinetic nystagmus

Journal of Vision, Mar 23, 2010

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Vision Research, Mar 1, 2007

We investigated localization of brief visual targets during reXexive eye movements (optokinetic n... more We investigated localization of brief visual targets during reXexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization diVers markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reXexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre-and post-saccadic scenes.

Research paper thumbnail of Systematic deviation of eye-movement direction from stimulus-direction during Optokinetic Nystagmus

Journal of Vision, Jul 25, 2013

Research paper thumbnail of Visual selectivity for heading in the macaque ventral intraparietal area

Journal of neurophysiology, Jan 15, 2014

The patterns of optic flow seen during self-motion can be used to determine the direction of one&... more The patterns of optic flow seen during self-motion can be used to determine the direction of one's own heading. Tracking eye movements which typically occur during everyday life alter this task since they add further retinal image motion and (predictably) distort the retinal flow pattern. Humans employ both visual and nonvisual (extraretinal) information to solve a heading task in such case. Likewise, it has been shown that neurons in the monkey medial superior temporal area (area MST) use both signals during the processing of self-motion information. In this article we report that neurons in the macaque ventral intraparietal area (area VIP) use visual information derived from the distorted flow patterns to encode heading during (simulated) eye movements. We recorded responses of VIP neurons to simple radial flow fields and to distorted flow fields that simulated self-motion plus eye movements. In 59% of the cases, cell responses compensated for the distortion and kept the same ...

Research paper thumbnail of The main sequence of human optokinetic nystagmus

Research paper thumbnail of Systematic deviation of eye-movement direction from stimulus-direction during Optokinetic Nystagmus

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Journal of Vision, 2010

ABSTRACT We investigated localization of brief visual targets during reflexive eye movements (opt... more ABSTRACT We investigated localization of brief visual targets during reflexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization differs markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reflexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre- and post-saccadic scenes.

Research paper thumbnail of Task influences on the dynamic properties of fast eye movements

Journal of Vision, 2009

It is widely debated whether fast phases of the reflexive optokinetic nystagmus (OKN) share prope... more It is widely debated whether fast phases of the reflexive optokinetic nystagmus (OKN) share properties with another class of fast eye movements, visually guided saccades. Conclusions drawn from previous studies were complicated by the fact that a subject's task influences the exact type of OKN: stare vs. look nystagmus. With our current study we set out to determine in the same subjects the exact dynamic properties (main sequence) of various forms of fast eye movements. We recorded fast phases of look and stare nystagmus as well as visually guided saccades. Our data clearly show that fast phases of look and stare nystagmus differ with respect to their main sequence. Fast phases of stare nystagmus were characterized by their lower peak velocities and longer durations as compared to fast phases of look nystagmus. Furthermore we found no differences between fast phases of stare nystagmus evoked with limited and unlimited dot lifetimes. Visually guided saccades were on the same main sequence as fast phases of look nystagmus, while they had higher peak velocities and shorter durations than fast phases of stare nystagmus. Our data underline the critical role of behavioral tasks (e.g., reflexive vs. intentional) for the exact spatiotemporal characteristics of fast eye movements.

Research paper thumbnail of Expansion of Visual Space During Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, 2008

The mechanisms underlying visual perceptual stability are usually investigated using voluntary ey... more The mechanisms underlying visual perceptual stability are usually investigated using voluntary eye movements. In such studies, errors in perceptual stability during saccades and pursuit are commonly interpreted as mismatches between actual eye position and eye-position signals in the brain. The generality of this interpretation could in principle be tested by investigating spatial localization during reflexive eye movements whose kinematics are very similar to those of voluntary eye movements. Accordingly, in this study, we determined mislocalization of flashed visual targets during optokinetic afternystagmus (OKAN). These eye movements are quite unique in that they occur in complete darkness and are generated by subcortical control mechanisms. We found that during horizontal OKAN slow phases, subjects mislocalize targets away from the fovea in the horizontal direction. This corresponds to a perceived expansion of visual space and is unlike mislocalization found for any other volunt...

Research paper thumbnail of The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

Journal of Neurophysiology, 2009

Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmu... more Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN), are coded by only partially overlapping neural networks. This is a likely cause for the differences that have been reported for the dynamic parameters of fast eye movements. The dependence of two of these parameters—peak velocity and duration—on saccadic amplitude has been termed “main sequence.” The main sequence of OKAN fast phases has not yet been analyzed. These eye movements are unique in that they are generated by purely subcortical control mechanisms and that they occur in complete darkness. In this study, we recorded fast phases of OKAN and OKN as well as visually guided and spontaneous saccades under identical background conditions because background characteristics have been reported to influence the main sequence of saccades. Our data clearly show that fast phases of OKAN and OKN differ with respect to their main sequence. OKAN fa...

Research paper thumbnail of Localization of visual targets during optokinetic eye movements

Vision Research, 2007

We investigated localization of brief visual targets during reXexive eye movements (optokinetic n... more We investigated localization of brief visual targets during reXexive eye movements (optokinetic nystagmus). Subjects mislocalized these targets in the direction of the slow eye movement. This error decreased shortly before a saccade and temporarily increased afterwards. The pattern of mislocalization diVers markedly from mislocalization during voluntary eye movements in the presence of visual references, but (spatially) resembles mislocalization during voluntary eye movements in darkness. Because neither reXexive eye movements nor voluntary eye movements in darkness have explicit (visual) goals, these data support the view that visual goals support perceptual stability as an important link between pre-and post-saccadic scenes.