Alfred O. DiScenna

Case Western Reserve University

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Ari Z. Zivotofsky

Bar-Ilan University

Vallabh E. Das

University of Houston

R. John Leigh

Case Western Reserve University

Richard Leigh

Johns Hopkins University

Lea Averbuch‐Heller

Case Western Reserve University

Klaus G. Rottach

University Hospital Augsburg

Cecil W. Thomas

University of Birmingham

Barbara Weissman

Children's Memorial Health Institute

Louis F. Dell’Osso

Case Western Reserve University

Regina D. von Maydell

Case Western Reserve University

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Case Western Reserve University

University Hospitals of Cleveland

University School

University Hospitals Case Medical Center

Veterans Health Administration

National Institutes of Health

Rainbow Babies & Children's Hospital

Mount Sinai Medical Center

Emory University

Cleveland Research (United States)

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Tests of a linear model of visual-vestibular interaction using the technique of parameter estimation

Biological Cybernetics (1998)

Vallabh E. Das Alfred O. DiScenna Andrew Feltz Stacy S. Yaniglos Richard Leigh

10.1007/s004220050425

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Citations (15)

Modulation of high-frequency vestibuloocular reflex during visual tracking in humans

Journal of Neurophysiology (1995)

Vallabh E. Das R. J. Leigh Cecil W. Thomas Lea Averbuch‐Heller Ari Z. Zivotofsky

1. Humans may visually track a moving object either when they are stationary or in motion. To investigate visual-vestibular interaction during both conditions, we compared horizontal smooth pursuit (SP) and active combined eye-head tracking (CEHT) of a target moving sinusoidally at 0.4 Hz in four normal subjects while the subjects were either stationary or vibrated in yaw at 2.8 Hz. We also measured the visually enhanced vestibuloocular reflex (VVOR) during vibration in yaw at 2.8 Hz over a peak head velocity range of 5–40 degrees/s. 2. We found that the gain of the VVOR at 2.8 Hz increased in all four subjects as peak head velocity increased (P < 0.001), with minimal phase changes, such that mean retinal image slip was held below 5 degrees/s. However, no corresponding modulation in vestibuloocular reflex gain occurred with increasing peak head velocity during a control condition when subjects were rotated in darkness. 3. During both horizontal SP and CEHT, tracking gains were similar, and the mean slip speed of the target's image on the retina was held below 5.5 degrees/s whether subjects were stationary or being vibrated at 2.8 Hz. During both horizontal SP and CEHT of target motion at 0.4 Hz, while subjects were vibrated in yaw, VVOR gain for the 2.8-Hz head rotations was similar to or higher than that achieved during fixation of a stationary target. This is in contrast to the decrease of VVOR gain that is reported while stationary subjects perform CEHT.(ABSTRACT TRUNCATED AT 250 WORDS)

Vestibulo–ocular reflex

10.1152/jn.1995.74.2.624

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Citations (25)

Dynamic properties of horizontal and vertical eye movements in parkinsonian syndromes

Annals of Neurology (1996)

Klaus G. Rottach David E. Riley Alfred O. DiScenna Ari Z. Zivotofsky Richard Leigh

Abstract We studied dynamic properties of horizontal, vertical, and oblique eye movements in 23 patients with the following parkinsonian syndromes: idiopathie parkinsonism (PD), multiple system atrophy (MSA), pure akinesia (PA), progressive supranuclear palsy (PSP), and cortical‐basal ganglionic degeneration (CBGD). Compared with age‐matched controls, only PSP patients showed slowing of saccades. Patients in all groups showed saccadic hypometria that was most marked vertically. The trajectories of saccades made to diagonal target jumps were deviated toward the horizonal plane, due to the vertical hypometria; this was most marked in PA and PSP groups. Saccade latency was only increased in the CBGD group. Sinusoidai smooth pursuit did not differentiate between controls and patients; however, with step‐ramp stimuli, pursuit eye acceleration was impaired in all patient groups compared with controls. The vestibulo‐ocular reflex, with or without visual enhancement, was similar in patients and controls. These findings indicate that (1) in parkinsonian syndromes apart from PSP, the saccade‐generating brainstem burst neurons are probably spared, but the signals that they receive, specifying the size and direction of saccades, are flawed; and (2) measurements of the gain and trajectory of oblique saccades, and initiation of smooth pursuit, may aid in diagnosing these different types of parkinsonism.

Horizontal and vertical

10.1002/ana.410390314

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Citations (179)

Book reviews

Neuro-Ophthalmology (1990)

Gregory S. Kosmorsky Robert L. Tomsak Alfred O. DiScenna

Compressive Optic Nerve Lesions at the Optic Canal: Pathogenesis - Diagnosis - TYeatment by R. Unsold and W. Seeger. Collaborators: M. Bach, H.-R. Eggert, G. Greeven, J. DeGroot. Springer-Verlag: 44 Hartz Way, Secaucus, N.J. 07094 (1989). $149.00 (U.S.) ISBN 0-387-18838-X.Human Brain Electrophysiology - Evoked Potentials and Evoked Magnetic Fields in Science and Medicine, D. Regan, Elsevier Science Publishing Co., New York, 1989, $145.00, ISBN 0-444-01324-5.

Nerve cells

10.3109/01658109008997263

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Evidence for independent feedback control of horizontal and vertical saccades from Niemann-Pick type C disease

Vision Research (1997)

Klaus G. Rottach Regina D. von Maydell Vallabh E. Das Ari Z. Zivotofsky Alfred O. DiScenna

Horizontal and vertical

Component (thermodynamics)

Vertical axis

10.1016/s0042-6989(96)00066-1

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Citations (71)

Investigations of the pathogenesis of acquired pendular nystagmus

Brain (1995)

Lea Averbuch‐Heller Ari Z. Zivotofsky Vallabh E. Das Alfred O. DiScenna R. John Leigh

We investigated the pathogenesis of acquired pendular nystagmus (APN) in six patients, three of whom had multiple sclerosis. First, we tested the hypothesis that the oscillations of APN are due to a delay in visual feedback secondary, for example, to demyelination of the optic nerves. We manipulated the latency to onset of visually guided eye movements using an electronic technique that induces sinusoidal oscillations in normal subjects. This manipulation did not change the characteristics of the APN, but did superimpose lower-frequency oscillations similar to those induced in normal subjects. These results are consistent with current models for smooth (non-saccadic) eye movements, which predict that prolongation of visual feedback could not account for the high-frequency oscillations that often characterize APN. Secondly, we attempted to determine whether an increase in the gain of the visually-enhanced vestibulo-ocular reflex (VOR), produced by viewing a near target, was accompanied by a commensurate increase in the amplitude of APN. Increases in horizontal or vertical VOR gain during near viewing occurred in four patients, but only two of them showed a parallel increase in APN amplitude. On the other hand, APN amplitude decreased during viewing of the near target in the two patients who showed no change in VOR gain. Taken together, these data suggest that neither delayed visual feedback nor a disorder of central vestibular mechanisms is primarily responsible for APN. More likely, these ocular oscillations are produced by abnormalities of internal feedback circuits, such as the reciprocal connections between brainstem nuclei and cerebellum.

Smooth pursuit

Vestibulo–ocular reflex

Optokinetic reflex

10.1093/brain/118.2.369

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Citations (84)

Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

Journal of Neurophysiology (1992)

William P. Huebner R. John Leigh Scott H. Seidman Cecil W. Thomas Carl Billian

1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible explanation for this discrepancy is that VOR gain can be dynamically modulated and, during sustained CEHT, it may assume a lower value. Consequently, during CEHT, a smaller-amplitude SP signal would be needed to cancel the lower-gain VOR. This reduction of the SP signal could account for the attenuated tracking response observed immediately after the brake. We found evidence for the dynamic modulation of VOR gain by noting differences in responses to the onset and offset of head rotation in trials of the visually enhanced VOR.(ABSTRACT TRUNCATED AT 400 WORDS)

Smooth pursuit

Vestibulo–ocular reflex

Stimulus (psychology)

10.1152/jn.1992.68.5.1775

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Citations (52)

Magnetic fields associated with the brain’s response to infrequent events

Il Nuovo Cimento D (1983)

Daryl Hess John L Patrick M.A. Stan Joanne Frankel J. H. Tripp

Stimulus (psychology)

Human brain

10.1007/bf02455949

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Citations (1)

Comparison of Horizontal, Vertical and Diagonal Smooth Pursuit Eye Movements in Normal Human Subjects

Vision Research (1996)

Klaus G. Rottach Ari Z. Zivotofsky Vallabh E. Das Lea Averbuch‐Heller Alfred O. DiScenna

Smooth pursuit

Horizontal and vertical

10.1016/0042-6989(95)00302-9

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Citations (112)

Downbeat nystagmus in an infant: Spontaneous resolution during infancy

Neuro-Ophthalmology (1988)

Barbara Weissman Louis F. Dell’Osso Alfred O. DiScenna

Downbeat nystagmus (DBN) has been associated with pathologic as well as idiopathic conditions. DBN may occur during infancy or childhood or may be congenital. In all reported cases, the DBN persisted. The authors report an infant with DBN that resolved within the first year of life.The patient's DBN was observed by six weeks of age. The patient preferred to keep her head in a chin-down position. Her physical and neurologic examination was otherwise normal. Family history contained no nystagmus. The DBN was documented by both vertical DC electro-oculography and infrared oculography. The DBN slow phases were predominantly of constant velocity. Subsquent magnetic resonance imaging studies and metabolic investigations were negative. The DBN was clinically undetectable at nine months of age. A repeat oculographic study at one year of age confirmed the resolution of DBN.It is suggested that, in this case, DBN was caused by an immaturity of central connections associated with the vertical canal pathways and its resolution paralleled their later maturation.

10.3109/01658108808996060

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Citations (12)