Contribution of Vestibular Commissural Pathways to Spatial Orientation of the Angular Vestibuloocular Reflex

1997 ◽  
Vol 78 (2) ◽  
pp. 1193-1197 ◽  
Author(s):  
Susan Wearne ◽  
Theodore Raphan ◽  
Bernard Cohen
Keyword(s):  
Spatial Orientation ◽  
Semicircular Canal ◽  
Vertical Axis ◽  
Vestibular Stimulation ◽  
Velocity Storage ◽  
Vestibuloocular Reflex ◽  
Time Constants ◽  
Commissural Pathways ◽  
Before And After ◽  
Axis Rotation

Wearne, Susan, Theodore Raphan, and Bernard Cohen. Contribution of vestibular commissural pathways to spatial orientation of the angular vestibuloocular reflex. J. Neurophysiol. 78: 1193–1197, 1997. During nystagmus induced by the angular vestibuloocular reflex (aVOR), the axis of eye velocity tends to align with the direction of gravitoinertial acceleration (GIA), a process we term “spatial orientation of the aVOR.” We studied spatial orientation of the aVOR in rhesus and cynomolgus monkeys before and after midline section of the rostral medulla abolished all oculomotor functions related to velocity storage, leaving the direct optokinetic and vestibular pathways intact. Optokinetic afternystagmus and the bias component of off-vertical-axis rotation were lost, and the aVOR time constant was reduced to a value commensurate with the time constants of primary semicircular canal afferents. Spatial orientation of the aVOR, induced either during optokinetic or vestibular stimulation, was also lost. Vertical and roll aVOR time constants could no longer be lengthened in side-down or supine/prone positions, and static and dynamic tilts of the GIA no longer produced cross-coupling from the yaw to pitch and yaw to roll axes. Consequently, the induced nystagmus remained entirely in head coordinates after the lesion, regardless of the direction of the resultant GIA vector. Gains of the aVOR and of optokinetic nystagmus to steps of velocity were unaffected or slightly increased. These results are consistent with a model in which the direct aVOR pathways are organized in semicircular canal coordinates and spatial orientation is restricted to the indirect (velocity storage) pathways.

Compensatory and Orienting Eye Movements Induced By Off-Vertical Axis Rotation (OVAR) in Monkeys

2002 ◽  
Vol 88 (5) ◽  
pp. 2445-2462 ◽  
Author(s):  
Keisuke Kushiro ◽  
Mingjia Dai ◽  
Mikhail Kunin ◽  
Sergei B. Yakushin ◽  
Bernard Cohen ◽  
...  
Keyword(s):  
Eye Movements ◽  
Vertical Axis ◽  
Velocity Storage ◽  
Eye Position ◽  
Rotational Axis ◽  
Vestibuloocular Reflex ◽  
Time Constants ◽  
Head Velocity ◽  
Axis Rotation ◽  
Eye Velocity

Nystagmus induced by off-vertical axis rotation (OVAR) about a head yaw axis is composed of a yaw bias velocity and modulations in eye position and velocity as the head changes orientation relative to gravity. The bias velocity is dependent on the tilt of the rotational axis relative to gravity and angular head velocity. For axis tilts <15°, bias velocities increased monotonically with increases in the magnitude of the projected gravity vector onto the horizontal plane of the head. For tilts of 15–90°, bias velocity was independent of tilt angle, increasing linearly as a function of head velocity with gains of 0.7–0.8, up to the saturation level of velocity storage. Asymmetries in OVAR bias velocity and asymmetries in the dominant time constant of the angular vestibuloocular reflex (aVOR) covaried and both were reduced by administration of baclofen, a GABAB agonist. Modulations in pitch and roll eye positions were in phase with nose-down and side-down head positions, respectively. Changes in roll eye position were produced mainly by slow movements, whereas vertical eye position changes were characterized by slow eye movements and saccades. Oscillations in vertical and roll eye velocities led their respective position changes by ≈90°, close to an ideal differentiation, suggesting that these modulations were due to activation of the orienting component of the linear vestibuloocular reflex (lVOR). The beating field of the horizontal nystagmus shifted the eyes 6.3°/ g toward gravity in side down position, similar to the deviations observed during static roll tilt (7.0°/ g). This demonstrates that the eyes also orient to gravity in yaw. Phases of horizontal eye velocity clustered ∼180° relative to the modulation in beating field and were not simply differentiations of changes in eye position. Contributions of orientating and compensatory components of the lVOR to the modulation of eye position and velocity were modeled using three components: a novel direct otolith-oculomotor orientation, orientation-based velocity modulation, and changes in velocity storage time constants with head position re gravity. Time constants were obtained from optokinetic after-nystagmus, a direct representation of velocity storage. When the orienting lVOR was combined with models of the compensatory lVOR and velocity estimator from sequential otolith activation to generate the bias component, the model accurately predicted eye position and velocity in three dimensions. These data support the postulates that OVAR generates compensatory eye velocity through activation of velocity storage and that oscillatory components arise predominantly through lVOR orientation mechanisms.

Vestibulo-ocular function in anxiety disorders

2007 ◽  
Vol 16 (4-5) ◽  
pp. 209-215
Author(s):  
Joseph M. Furman ◽  
Mark S. Redfern ◽  
Rolf G. Jacob
Keyword(s):  
Panic Disorder ◽  
Anxiety Disorders ◽  
Semicircular Canal ◽  
Constant Velocity ◽  
Vertical Axis ◽  
Velocity Storage ◽  
Movement Response ◽  
Ocular Reflex ◽  
Axis Rotation ◽  
High Degree

Previous studies of vestibulo-ocular function in patients with anxiety disorders have suggested a higher prevalence of peripheral vestibular dysfunction compared to control populations, especially in panic disorder with agoraphobia. Also, our recent companion studies have indicated abnormalities in postural control in patients with anxiety disorders who report a high degree of space and motion discomfort. The aim of the present study was to assess the VOR, including the semicircular canal-ocular reflex, the otolith-ocular reflex, and semicircular canal-otolith interaction, in a well-defined group of patients with anxiety disorders. The study included 72 patients with anxiety disorders (age 30.6 +/− 10.6 yrs; 60 (83.3% F) and 29 psychiatrically normal controls (age 35.0 +/minus; 11.6 yrs; 24 (82.8% F). 25 patients had panic disorder; 47 patients had non-panic anxiety. Patients were further categorized based on the presence (45 of 72) or absence (27 of 72) of height phobia and the presence (27 of 72) or absence (45 of 72) of excessive space and motion discomfort (SMD). Sinusoidal and constant velocity earth-vertical axis rotation (EVAR) was used to assess the semicircular canal-ocular reflex. Constant velocity off-vertical axis rotation (OVAR) was used to assess both the otolith-ocular reflex and static semicircular canal-otolith interaction. Sinusoidal OVAR was used to assess dynamic semicircular canal-otolith interaction. The eye movement response to rotation was measured using bitemporal electro-oculography. Results showed a significantly higher VOR gain and a significantly shorter VOR time constant in anxiety patients. The effect of anxiety on VOR gain was significantly greater in patients without SMD as compared to those with SMD. Anxiety patients without height phobia had a larger OVAR modulation. We postulate that in patients with anxiety, there is increased vestibular sensitivity and impaired velocity storage. Excessive SMD and height phobia seem to have a mitigating effect on abnormal vestibular sensitivity, possibly via a down-weighting of central vestibular pathways.

Rotational kinematics of the human vestibuloocular reflex. II. Velocity steps

1994 ◽  
Vol 72 (5) ◽  
pp. 2480-2489 ◽  
Author(s):  
D. Tweed ◽  
M. Fetter ◽  
D. Sievering ◽  
H. Misslisch ◽  
E. Koenig
Keyword(s):  
Cross Talk ◽  
Human Subjects ◽  
Head Rotation ◽  
Horizontal Axis ◽  
Main Diagonal ◽  
Velocity Storage ◽  
Vestibuloocular Reflex ◽  
Simple Explanation ◽  
Time Constants ◽  
Axis Rotation

1. Gain matrices were used to quantify the three-dimensional vestibuloocular reflex (VOR) in five human subjects who were accelerated over 1 s and then spun at a constant 150 degrees/s for 29 s in darkness. Rotations were torsional, vertical and horizontal, about earth-vertical and earth-horizontal axes. 2. Elements on the main diagonal of the gain matrices were much smaller than the optimal value of -1, and torsional gain was weaker than vertical or horizontal. Off-diagonal elements, indicating cross talk, were minimal except for a small but consistent horizontal response to torsional head rotation. 3. Downward slow phases were more than twice as fast as upward at the start of rotation about both earth-vertical and earth-horizontal axes, but the asymmetry vanished later in the rotation. 4. During earth-vertical-axis rotation, all matrix elements decayed to zero. The main-diagonal torsional and vertical gains waned with time constants close to that of the cupula (6.7 and 7.3 s). Velocity storage prolonged the horizontal response to horizontal head rotation (time constant 14.2 s) but not the horizontal response to torsion (7.7 s). A simple explanation is that velocity storage acts on a central estimate of head motion that accurately distinguishes horizontal from torsional and that the inappropriate horizontal eye velocity response to torsion occurs because of cross talk downstream from velocity storage. 5. During earth-horizontal-axis rotation, the torsional, vertical, and horizontal main-diagonal elements declined, with time constants of 7.6, 8.2, and 7.9 s, to maintained nonzero values, all equal to about -0.1. Off-diagonal elements, including the horizontal response to torsion, decayed to zero, so that the otolith-driven reflex, late in the rotation, was equally strong in all dimensions and almost free of detectable cross talk. 6. The difference between gain curves over the course of earth-vertical- and earth-horizontal-axis rotations was not constant but increased with time, suggesting that the VOR response to earth-horizontal-axis rotation is not a simple sum of canal and otolith reflexes.

Vestibuloocular reflex of rhesus monkeys after spaceflight

1992 ◽  
Vol 73 (2) ◽  
pp. S121-S131 ◽  
Author(s):  
B. Cohen ◽  
I. Kozlovskaya ◽  
T. Raphan ◽  
D. Solomon ◽  
D. Helwig ◽  
...  
Keyword(s):  
Steady State ◽  
Time Constant ◽  
Rhesus Monkeys ◽  
Vertical Axis ◽  
Vestibuloocular Reflex ◽  
Before And After ◽  
The Central Nervous System ◽  
Axis Rotation ◽  
The One ◽  
Eye Velocity

The vestibuloocular reflex (VOR) of two rhesus monkeys was recorded before and after 14 days of spaceflight. The gain (eye velocity/head velocity) of the horizontal VOR, tested 15 and 18 h after landing, was approximately equal to preflight values. The dominant time constant of the animal tested 15 h after landing was equivalent to that before flight. During nystagmus induced by off-vertical axis rotation (OVAR), the latency, rising time constant, steady-state eye velocity, and phase of modulation in eye velocity and eye position with respect to head position were similar in both monkeys before and after flight. There were changes in the amplitude of modulation of horizontal eye velocity during steady-state OVAR and in the ability to discharge stored activity rapidly by tilting during postrotatory nystagmus (tilt dumping) after flight: OVAR modulations were larger, and tilt dumping was lost in the one animal tested on the day of landing and for several days thereafter. If the gain and time constant of the horizontal VOR change in microgravity, they must revert to normal soon after landing. The changes that were observed suggest that adaptation to microgravity had caused alterations in way that the central nervous system processes otolith input.

Spatial orientation of periodic alternating drift (PAD)

2007 ◽  
Vol 16 (4-5) ◽  
pp. 201-207
Author(s):  
Aldo Ferraresi ◽  
Gian Battista Azzena ◽  
Diana Troiani
Keyword(s):  
Prone Position ◽  
Time Constant ◽  
Spatial Orientation ◽  
Vertical Component ◽  
Vertical Axis ◽  
Longitudinal Axis ◽  
Vestibular Stimulation ◽  
Horizontal Component ◽  
Velocity Storage ◽  
Pigmented Rabbits

Sinusoidal vestibular stimulation induces in the intact rabbit in prone position a periodic alternating drift (PAD), evident in the earth horizontal plane when the animal is rotated about the vertical axis but weak in the vertical one when the animal is rotated about the longitudinal axis. It has been hypothesized that these oscillations are related to an intrinsic instability of the velocity storage, due to the length of its time constant. The velocity storage has the longest time constant aligned with the vertical axis, and it changes its orientation with the gravity vector. The present research examined the spatial orientation of PAD in relation to changes of the animal position with respect to gravity. Normal pigmented rabbits were sinusoidally oscillated about their longitudinal axes to evoke vertical eye responses. The stimulation was carried out with the animal in prone position and with the animal in nose-up condition. With the animal in prone position, PAD had a weak vertical component, but an evident horizontal component was visible. When the animal was in nose-up position, the horizontal component of PAD was clearly visible, while the vertical component was negligible. In both stimulation conditions PAD period and peak velocity were not modulated by the stimulus characteristics. These results are consistent with a model of PAD based on an interaction between velocity storage and the cerebellar adaptation-habituation circuit.

Control of Spatial Orientation of the Angular Vestibuloocular Reflex by the Nodulus and Uvula

1998 ◽  
Vol 79 (5) ◽  
pp. 2690-2715 ◽  
Author(s):  
Susan Wearne ◽  
Theodore Raphan ◽  
Bernard Cohen
Keyword(s):  
Spatial Orientation ◽  
Three Dimensional ◽  
Cross Coupling ◽  
Velocity Storage ◽  
Coordinate Frame ◽  
Vestibuloocular Reflex ◽  
Time Constants ◽  
Vertical Roll ◽  
Eye Rotation ◽  
Eye Velocity

Wearne, Susan, Theodore Raphan, and Bernard Cohen. Control of spatial orientation of the angular vestibuloocular reflex by the nodulus and uvula. J. Neurophysiol. 79: 2690–2715, 1998. Spatial orientation of the angular vestibuloocular reflex (aVOR) was studied in rhesus monkeys after complete and partial ablation of the nodulus and ventral uvula. Horizontal, vertical, and torsional components of slow phases of nystagmus were analyzed to determine the axes of eye rotation, the time constants (Tcs) of velocity storage, and its orientation vectors. The gravito-inertial acceleration vector (GIA) was tilted relative to the head during optokinetic afternystagmus (OKAN), centrifugation, and reorientation of the head during postrotatory nystagmus. When the GIA was tilted relative to the head in normal animals, horizontal Tcs decreased, vertical and/or roll time constants (Tcvert/roll) lengthened according to the orientation of the GIA, and vertical and/or roll eye velocity components appeared (cross-coupling). This shifted the axis of eye rotation toward alignment with the tilted GIA. Horizontal and vertical/roll Tcs varied inversely, with Tchor being longest and Tcvert/roll shortest when monkeys were upright, and the reverse when stimuli were around the vertical or roll axes. Vertical or roll Tcs were longest when the axes of eye rotation were aligned with the spatial vertical, respectively. After complete nodulo-uvulectomy, Tchor became longer, and periodic alternating nystagmus (PAN) developed in darkness. Tchor could not be shortened in any of paradigms tested. In addition, yaw-to-vertical/roll cross-coupling was lost, and the axes of eye rotation remained fixed during nystagmus, regardless of the tilt of the GIA with respect to the head. After central portions of the nodulus and uvula were ablated, leaving lateral portions of the nodulus intact, yaw-to-vertical/roll cross-coupling and control of Tcvert/roll was lost or greatly reduced. However, control of Tchor was maintained, and Tchor continued to vary as a function of the tilted GIA. Despite this, the eye velocity vector remained aligned with the head during yaw axis stimulation after partial nodulo-uvulectomy, regardless of GIA orientation to the head. The data were related to a three-dimensional model of the aVOR, which simulated the experimental results. The model provides a basis for understanding how the nodulus and uvula control processing within the vestibular nuclei responsible for spatial orientation of the aVOR. We conclude that the three-dimensional dynamics of the velocity storage system are determined in the nodulus and ventral uvula. We propose that the horizontal and vertical/roll Tcs are separately controlled in the nodulus and uvula with the dynamic characteristics of vertical/roll components modulated in central portions and the horizontal components laterally, presumably in a semicircular canal-based coordinate frame.

Spatial orientation of postrotatory nystagmus during static roll tilt in cats

2002 ◽  
Vol 12 (1) ◽  
pp. 15-23
Author(s):  
Keiko Yasuda ◽  
Hiroaki Fushiki ◽  
Rinnosuke Wada ◽  
Yukio Watanabe
Keyword(s):  
Spatial Orientation ◽  
Vertical Axis ◽  
Longitudinal Axis ◽  
Velocity Storage ◽  
Slow Phase ◽  
Storage Mechanism ◽  
Spatial Disorientation ◽  
Acceleration And Deceleration ◽  
Eye Velocity ◽  
Roll Tilt

While the stimulation of otolith inputs reduces the duration of postrotatory nystagmus (PRN), there is still room for dialogue about the effect of static tilt on the orientation of PRN. We studied one possible influence of static roll tilt on the spatial orientation of PRN in cats. The animal was rotated about an earth-vertical axis (EVA) at a constant velocity of 100 deg/s with an acceleration and deceleration of 120 deg / s 2 . Within two seconds after stopping EVA rotation, the animal was passively tilted at 45 deg/s about its longitudinal axis by as much as ± 90 deg in steps of 15 deg. Eye movements were measured with magnetic search coils. The angle of the PRN plane and its slow phase eye velocity were measured. The time constant of PRN decreased with an increase in roll tilt. The PRN plane remained earth horizontal within a range of ± 30 deg roll tilt. Beyond this range, the velocity of PRN decreased too rapidly to measure any change in orientation. Our results indicate a spatially limited and temporally short interaction of the semicircular canal and otolith signals in the velocity storage mechanism of cat PRN. Our data, along with previous studies, suggest that different species show different solutions to the problem of the imbalance and spatial disorientation during contradictory stimuli.

Responses to vertical vestibular stimulation of neurons in the nucleus reticularis gigantocellularis in rabbits

1995 ◽  
Vol 73 (6) ◽  
pp. 2378-2391 ◽  
Author(s):  
M. H. Fagerson ◽  
N. H. Barmack
Keyword(s):  
Semicircular Canal ◽  
Head Tilt ◽  
Vertical Axis ◽  
Vestibular Nuclei ◽  
Vestibular Stimulation ◽  
Medial Aspect ◽  
Unit Recording ◽  
Nucleus Reticularis ◽  
Nucleus Reticularis Gigantocellularis ◽  
Electrolytic Lesions

1. Because the nucleus reticularis gigantocellularis (NRGc) receives a substantial descending projection from the caudal vestibular nuclei, we used extracellular single-unit recording combined with natural vestibular stimulation to examine the possible peripheral origins of the vestibularly modulated activity of caudal NRGc neurons located within 500 microns of the midline. Chloralose-urethan anesthetized rabbits were stimulated with an exponential "step" and/or static head-tilt stimulus, as well as sinusoidal rotation about the longitudinal or interaural axes providing various combinations of roll or pitch, respectively. Recording sites were reconstructed from electrolytic lesions confirmed histologically. 2. More than 85% of the 151 neurons, in the medial aspect of the caudal NRGc, responded to vertical vestibular stimulation. Ninety-six percent of these responded to rotation onto the contralateral side (beta responses). Only a few also responded to horizontal stimulation. Seventy-eight percent of the neurons that responded to vestibular stimulation responded during static roll-tilt. One-half of these neurons also responded transiently to the change in head position during exponential "step" stimulation, suggesting input mediated by otolith and semicircular canal receptors or tonic-phasic otolith neurons. 3. Seventy-five percent of the responsive neurons had a "null plane." The planes of stimulation resulting in maximal responses, for cells that responded to static stimulation, were distributed throughout 150 degrees in both roll and pitch quadrants. Five of these cells responded only transiently during exponential "step" stimulation and responded maximally when stimulated in the plane of one of the vertical semicircular canals. 4. The phase of the response of the 25% of medial NRGc neurons that lacked "null planes" gradually shifted approximately 180 degrees during sinusoidal vestibular stimulation as the plane of stimulation was shifted about the vertical axis. These neurons likely received convergent input with differing spatial and temporal properties. 5. The activity of neurons in the medial aspect of the caudal NRGc of rabbits was modulated by both otolithic macular and vertical semicircular canal receptor stimulation. This vestibular information may be important for controlling the intensity of the muscle activity in muscles such as neck muscles where the load on the muscle is affected by the position of the head with respect to gravity. Some of these neurons may also shift muscle function from an agonist to an antagonist as the direction of head tilt changes.

Effect of aging on the otolith-ocular reflex

2001 ◽  
Vol 11 (2) ◽  
pp. 91-103
Author(s):  
Joseph M. Furman ◽  
Mark S. Redfern
Keyword(s):  
Semicircular Canal ◽  
Head Tilt ◽  
Vestibular Function ◽  
Vertical Axis ◽  
Ocular Reflex ◽  
Age Related ◽  
Vestibulo Ocular Reflex ◽  
Older Subjects ◽  
Axis Rotation ◽  
Reflex Time

We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.

Unilateral Peripheral Semicircular Canal Lesion and Off-Vertical Axis Rotation

1996 ◽  
Vol 116 (3) ◽  
pp. 361-367 ◽  
Author(s):  
P. Denise ◽  
C. Darlot ◽  
P. Ignatiew-Charles ◽  
M. Toupet
Keyword(s):  
Semicircular Canal ◽  
Vertical Axis ◽  
Axis Rotation
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