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static roll vor

Richard F Lewis, Csilla Haburcakova, Wangsong Gong, Faisal Karmali, Daniel M Merfeld
To investigate the characteristics of eye movements produced by electrical stimulation of semicircular canal afferents, we studied the spatial and temporal features of eye movements elicited by short-term lateral canal stimulation in two squirrel monkeys with plugged lateral canals, with the head upright or statically tilted in the roll plane. The electrically induced vestibuloocular reflex (eVOR) evoked with the head upright decayed more quickly than the stimulation signal provided by the electrode, demonstrating an absence of the classic velocity storage effect that improves the dynamics of the low-frequency VOR...
September 2012: Journal of Neurophysiology
Richard F Lewis, Csilla Haburcakova, Wangsong Gong, Daniel Lee, Conrad Wall, Lara Thompson, Daniel M Merfeld
We are studying the effectiveness of a semicircular canal prosthesis to improve postural control, perception of spatial orientation, and the VOR in rhesus monkeys with bilateral vestibular hypofunction. Balance is examined by measuring spontaneous sway of the body during quiet stance and postural responses evoked by head turns and rotation of the support surface; perception is measured with a task derived from the subjective visual vertical (SVV) test during static and dynamic rotation in the roll plane; and the angular VOR is measured during rotation about the roll, pitch, and yaw axes...
2011: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
S Marti, A A Tarnutzer, A Palla, D Straumann
Cerebellar degeneration affects vestibular function. For instance, with lesions of the cerebellar flocculus, the ability to adaptively modify the VOR gain is markedly reduced, and cerebellar patients may even demonstrate severe vestibular deficits. We report five patients (m=3, f=2) with cerebellar disease, in whom search-coil head impulse testing revealed reduced gains of the angular VOR, while sacculus-mediated myogenic potentials were normal. Preserved static ocular counterroll in roll-tilt positions and prominent gravity-dependent modulation of downbeat nystagmus (DBN) along the pitch plane demonstrated the integrity of otolith (OL) function in these patients as well...
2008: Progress in Brain Research
Agnes M F Wong, James A Sharpe
BACKGROUND: Skew deviation is typically caused by brainstem damage, and has not been identified with focal cerebellar lesions. This vertical strabismus has been attributed to asymmetric disruption of vestibuloocular reflex (VOR) projections from otolithic receptors of the utricle to ocular motoneurons, but asymmetry of the utriculo-ocular counter-roll reflex has not been detected. METHODS: Lesions localized to the cerebellum were identified by MRI in five patients with vertical strabismus...
August 9, 2005: Neurology
Joseph L Demer, Robert A Clark
The rectus extraocular muscle (EOM) pulleys constrain EOM paths. During visual fixation with head immobile, actively controlled pulleys are known to maintain positions causing EOM pulling directions to change by one-half the change in eye position. This pulley behavior is consistent with Listing's law (LL) of ocular torsion as observed during fixation, saccades, and pursuit. However, pulley behavior during the vestibulo-ocular reflex (VOR) has been unstudied. This experiment studied ocular counter-rolling (OCR), a static torsional VOR that violates LL but can be evoked during MRI...
November 2005: Journal of Neurophysiology
James A Sharpe, Douglas Tweed, Agnes M F Wong
Palsy of a nerve might be expected to lower vestibulo-ocular reflex (VOR) responses in its fields of motion, but effects of peripheral neuromuscular disease were unknown. We recorded the VOR during sinusoidal head rotations in yaw, pitch, and roll at 0.5-2 Hz and static torsional gain in 43 patients with unilateral nerve palsies. Sixth nerve palsy (n = 21) reduced both abduction and adduction VOR gains in darkness. In light, horizontal visually enhanced VOR (VVOR) gains were normal in moderate and mild palsy...
October 2003: Annals of the New York Academy of Sciences
Christopher G Harrod, James F Baker
The horizontal and vertical vestibulo ocular reflex (VOR) of head tilted (het) mutant mice was compared to C57BL/6 controls. Eye movements were recorded in darkness using a temporarily attached search coil. Contributions of semicircular canal versus otolith organ signals were investigated by providing a canal only (vertical axis) or canal plus otolith organ (horizontal axis) stimulus. In controls, rotations that stimulated only the canals (upright yaw and on tail roll) produced accurate VOR timing during middle frequency rotations at 0...
May 16, 2003: Brain Research
Agnes M F Wong, James A Sharpe
OBJECTIVE: To analyze the vestibulo-ocular reflex (VOR) in patients with unilateral peripheral third nerve palsy. PARTICIPANTS AND METHODS: Ten patients and 15 healthy subjects were studied using magnetic search coils. Subjects made sinusoidal +/-10 degrees head-on-body rotations in yaw, pitch, and roll in darkness and during monocular viewing in light. RESULTS: Horizontal VOR and visually enhanced VOR (VVOR) gains of the paretic eye were decreased during both abduction and adduction...
March 2002: Archives of Ophthalmology
Agnes M F Wong, Douglas Tweed, James A Sharpe
PURPOSE: The effects of paralytic strabismus on the vestibulo-ocular reflex (VOR) have not been systematically investigated in humans. The purpose of this study was to analyze the VOR in patients with unilateral peripheral sixth nerve palsy. METHODS: Twenty-one patients with unilateral peripheral sixth nerve palsy (6 severe, 7 moderate, 8 mild) and 15 normal subjects were studied. Subjects made sinusoidal +/-10 degrees head-on-body rotations in yaw and pitch at approximately 0...
January 2002: Investigative Ophthalmology & Visual Science
C E Sebastian, K Pfau, E R Horn
In tadpoles of the Southern Clawed Toad (Xenopus laevis), the effects of an exposure to hypergravity of several days duration on the development of the roll-induced static vestibuloocular reflex (rVOR) were investigated. Special attention was given to the onset of the 9 or 12 days lasting 3G-period during early life. First recordings of the rVOR characteristics for complete 360 degrees rolls of the tadpoles were performed 24 hrs after the end of the 3G-period. The rVOR peak-to-peak amplitudes as well as the VOR-gain for a roll angle of 15 degrees from 3G-and 1G-samples recorded at the 2nd and 3rd day after 3G-termination agreed for the youngest group, but were reduced by approx...
January 1998: Acta Astronautica
C Sebastian, E Horn, K Esseling, J Neubert
The effects of altered gravitational conditions (AGC) on the development of the static vestibulo-ocular reflex (VOR) and readaptation to 1g were investigated in the amphibian Xenopus laevis. Tadpoles were exposed to microgravity during the German Space Mission D-2 for 10 days, using the STATEX closed survival system, or to 3g for 9 days during earth-bound experiments. At the beginning of AGC, the tadpoles had not yet developed the static VOR. The main results were: (i) Tadpoles with microgravity- or 3g-experience had a lower gain of the static VOR than the 1g-controls during the 2nd and 5th post-AGC days...
October 1995: Acta Astronautica
S C Brettler, S A Rude, K J Quinn, J E Killian, E C Schweitzer, J F Baker
Horizontal and vertical eye movements were recorded in alert pigmented rats using chronically implanted scleral search coils or temporary glue-on coils to test the dependence of the vestibulo-ocular reflex (VOR) upon rotation axis and body orientation. The contributions of semicircular-canal versus otolith-organ signals to the VOR were investigated by providing canal-only (vertical axis) and canal plus otolith (horizontal axis) stimulation conditions. Rotations that stimulated canals only (upright yaw and nose-up roll) produced an accurate VOR during middle- and high-frequency rotations (0...
June 2000: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
A Schmid-Priscoveanu, D Straumann, A Böhmer, H Obzina
This study aimed to investigate whether unilateral vestibular neuritis (VN) causes the same deficits of ocular counter-roll during static head roll (OCR(S)) and dynamic vestibulo-ocular reflex gains during head impulses (VOR(HI)) as unilateral vestibular deafferentation (VD). Ten patients with acute and 14 patients with chronic vestibular paralysis after VN were examined. The testing battery included fundus photography of both eyes with the head upright (binocular cyclorotation) and dual search coil recordings in a three-field magnetic frame...
1999: Acta Oto-laryngologica
D E Angelaki
The three-dimensional (3-D) properties of the translational vestibulo-ocular reflexes (translational VORs) during lateral and fore-aft oscillations in complete darkness were studied in rhesus monkeys at frequencies between 0.16 and 25 Hz. In addition, constant velocity off-vertical axis rotations extended the frequency range to 0.02 Hz. During lateral motion, horizontal responses were in phase with linear velocity in the frequency range of 2-10 Hz. At both lower and higher frequencies, phase lags were introduced...
August 1998: Journal of Neurophysiology
C Helmchen, H Rambold, L Fuhry, U Büttner
The mesencephalic interstitial nucleus of Cajal (iC) is considered the neural integrator for vertical and torsional eye movements and has also been proposed to be involved in saccade generation. The aim of this study was to elucidate the function of iC in neural integration of different types of eye movements and to distinguish eye movement deficits due to iC impairment from that of the immediately adjacent rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). We addressed the following questions: (1) According to the neural integrator hypothesis, all eye movements including the saccadic system and the vestibulo-ocular reflex (VOR) share a common neural integrator...
April 1998: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
H Kingma
Quantification of eye torsion induced by stimulation of the statolith organ has recently become available (in the clinic) thanks to the development of video nystagmography. A major step forward has been the development of real-time measurement of eye torsion which enables interactive testing of the statolith-ocular reflex. The function of the statolith organs can be evaluated by the study of the impact of statolith stimulation upon the canal-mediated dynamic vestibulo-ocular reflex (VOR) or by measurement of the static VOR...
July 1997: ORL; Journal for Oto-rhino-laryngology and its related Specialties
C Sebastian, K Esseling, E Horn
The effects of altered gravitational forces (AGF) on the development of the static vestibulo-ocular reflex (VOR) were investigated in Xenopus laevis tadpoles exposed to hypergravity (1.4g; 3g) or microgravity conditions (German spacelab mission D-2) for 9-10 days. The effects of light conditions during development were also tested by exposing tadpoles to either complete darkness (DD) or 12:12 h light-dark conditions (LD). The static VOR was induced by lateral roll. The efficacy of the VOR circuit after termination of AGF conditions was described by the peak-to-peak amplitude of the sinusoidal VOR characteristics (i...
November 1996: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
S Yakushin, M Dai, J Suzuki, T Raphan, B Cohen
1. We studied the contribution of the individual semicircular canals to the generation of horizontal and torsional eye movements in cynomolgus monkeys. Eye movements were elicited by sinusoidal rotation about a vertical (gravitational) axis at 0.2 Hz with the animals tilted in various attitudes of static forward or backward pitch. The gains of the horizontal and torsional components of the vestibuloocular reflex (VOR) were measured for each tilt position. The gains as a function of tilt position were fit with sinusoidal functions, and spatial gains and phases were determined...
December 1995: Journal of Neurophysiology
C Tiliket, M Shelhamer, H S Tan, D S Zee
We investigated the influence of static head orientation and position, relative to the axis of body rotation, upon vestibular adaptation. With the head centered, displaced anterior to the axis of body rotation, or tilted 40 degrees to 45 degrees in roll or pitch, the gain of the vestibulo-ocular reflex (VOR) was trained (to go either up or down) for one hour using artificial manipulation of the visual surround to produce a visual-vestibular mismatch. Before and after each training session, the VOR was measured in darkness with the head in the training as well as in several non-training positions...
1993: Journal of Vestibular Research: Equilibrium & Orientation
M Dai, L McGarvie, I Kozlovskaya, T Raphan, B Cohen
We recorded the horizontal (yaw), vertical (pitch), and torsional (roll) eye movements of two rhesus monkeys with scleral search coils before and after the COSMOS Biosatellite 2229 Flight. The aim was to determine effects of adaptation to microgravity on the vestibulo-ocular reflex (VOR). The animals flew for 11 days. The first postflight tests were 22 h and 55 h after landing, and testing extended for 11 days after reentry. There were four significant effects of spaceflight on functions related to spatial orientation: (1) Compensatory ocular counterrolling (OCR) was reduced by about 70% for static and dynamic head tilts with regard to gravity...
1994: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
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