Ocular Responses to Head Rotations During Mirror Viewing

Han, Yong Seop; Somers, Jeffrey T.; Kim, Jae Il; Kumar, Arun N.; Leigh, R. John

doi:10.1152/jn.2001.86.5.2323

Cited by 7 publications

(15 citation statements)

References 10 publications

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“…Under these conditions, four of the subjects showed a greater vergence angle, but the gain of EVOR was not increased compared with monocular viewing. In vergence angle is not correlated with VOR gain during near viewing is consistent with our former study of visually enhanced VOR during mkor viewing (Han et al 2001). …”

Section: Vergence Angle and The Compensatory Response During Near Viesupporting

confidence: 92%

“…Special demands are made when subjects v i m a new, earth-fmed stationary target during head rotations (BlakemoE and Donaghy 1980;Biger and Prablanc 1981 ;Viirre et al 1986; Hine and Thorn 1987;Han et al 2001). Since the eyes do not lie on the axk of head rotation, t h y are displaced (translated) as well as rotated whm the head tums.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we refer to the sum of vestibular and non-vestibular factors contributing to eye movements th& compensate for head rotations as the enhanced VOR (EVOR). How much nomvestibular factors contribute to EVOR appears to vary according to species and test paradigms.Special demands are made when subjects v i m a new, earth-fmed stationary target during head rotations (BlakemoE and Donaghy 1980; Biger and Prablanc 1981 ; Viirre et al 1986;Hine and Thorn 1987;Han et al 2001). Since the eyes do not lie on the axk of head rotation, t h y are displaced (translated) as well as rotated whm the head tums.…”

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confidence: 99%

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Vestibular and non-vestibular contributions to eye movements that compensate for head rotations during viewing of near targets

et al. 2005

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We studied horizontal eye movements induced by en-bloc yaw rotation, over a frequency range 0.2 -2.8 Hz, in 10 normal h u m subjects as they monocularly viewed a target located at their near pomt of focus. We measured gain and phase relationships between eysin-head velocity and head velocity when the near target was either earth-fiued or head-fixd. During viewingoftheearth-fDced near tqet,median gam was 1.49 (range 1.24 -1.87) at 0.2 Hz for the group of subjects, but declined at hi&er frequencies, so that at 2.8 Hz median gim was 1.08 (range 0.68 -1.67). During viewing of the head-fixd near target, median gam was 0.03 (range 0.01 -0.10) at 0.2 Hz for the group of subjects, but increased at hi&er frequencies, so that at 2.8 Hz median gain was 0.71 (range 0.28 -0.94). We estimated the vestibular contribution to these responses (vestibulo-ocular reflex g m , Gvor) by applying transient head perturbations (peak acceleration> 1,000 deg's2) during sinusoidal rotation under the two viewing conditions. Median Gvor, estimated < 7 0 m after the onset of head perturbation, was 0.98 (range 0.39 -1.42) while viewingtheearth-fDed near target, and 0.97 (range 0.37 -1.33) while viewing the head-fixd near tatget. For the group of subjects, 9 out of 10 subjects showed no sigificant difference of Gvor between the two viavingconditions ( p > 0.053 ) at all test frequencies.Since Gvor accounted for only -73% of the overall response gain during viaving of the earthfixd target, we investigited the relative contributions of non-vestibular factors. When subjects viewed the earth-fDced target under strobe illumination, to eliminate retinal image slip information, the gain of compensatory eye movements declined compared with viewing in ambient room li&t. During sumof-sine head rotations, while viewing the earth-ftued tatget, to Han et al., NOR during near-viewing minimize contributions from predictive mechanisms, gim also declined Nonetheless, simple superposition of smooth-pursuit tracking of sinusoidal target motion could not fully account for the overall response at higJer frequencies, suggesting other non-vestibular contributions.During binocular viewing conditions when vergence angle was sigpificantly greater than monocular viewing (p < O.oOl), ths gim of compensatory eye movemeEts did not show proportional change; indeed, gam could not be con-elated with vergence ande during monocular or binocular viewing. We conclude that several separate factors contribute to generate eye rotations during sinusoidal yaw head rotations while viewing a near target; these include the VOR, visual-tracking eye movements that utilize retinal image motion, predictive eye movements and, possibly, other unidentified norrvestibular factors. For these experiments, vergence was not an import& determinant of response gam. I N T R O D U C T I O NIn order to see the enviromnt clearly, images of stationary objects must be held fairly still on the retina (Carpenter 1991). During natural activities, especially lommotbn, head perturbations with predominant f...

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Section: Vergence Angle and The Compensatory Response During Near Viesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Vestibular and non-vestibular contributions to eye movements that compensate for head rotations during viewing of near targets

et al. 2005

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“…12,13 To interpret the significance of this finding, we briefly review what potential effect each of these visual stimuli might have on PAN, based on current concepts of its pathogenesis.…”

Section: T H I R D S E S S I Omentioning

confidence: 99%

“…Thus, visual inputs might influence PAN (1) through a visual fixation mechanism, 1 (2) through optokinetic inputs (which normally summate with vestibular nucleus neurons and influence 'velocity storage'), 10,11 or (3) because viewing a near target adjusts the vestibular responses to take account of the geometric fact that the eyes do not lie at the center of rotation of the head. 12,13 Evidence to support the visual fixation mechanism is that patients have been reported who have developed PAN following visual loss, and the nystagmus subsequently resolved after sight was restored. 14,15 Similarly, PAN is suppressed during vision in the monkey model for PAN.…”

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confidence: 99%

Effects of visual fixation and convergence on periodic alternating nystagmus due to MS

Garbutt

Thakore

Rucker

et al. 2004

Neuro-Ophthalmology

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We studied a young woman with multiple sclerosis, who developed periodic alternating nystagmus (PAN) with a period of oscillation of about three minutes. Neither visual fixation of a stationary target nor large-field optokinetic stimulation substantially influenced the cycle of PAN. During convergence, induced by fixation of a near target, PAN was suppressed by over 70%. Treatment with baclofen abolished her nystagmus, but optokinetic and pursuit responses remained impaired. Convergence during viewing a near target did not increase the response (gain) of her vestibulo-ocular reflex. We postulate that visual drives were able to suppress PAN independently of any effects on vestibular responses and were prevented from exerting effects on velocity storage and vestibular gain adjustment by demyelinating lesions affecting her pontine nuclei and cerebellar circuits.

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Vestibulo-ocular responses to vertical translation in normal human subjects

et al. 2007

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Prior studies of the human translational vestibulo-ocular reflex (tVOR) report that eye rotations amount to less than 60% of those required to keep the eyes pointed at a stationary visual target, unlike the angular VOR (aVOR) which is optimized to maintain stable gaze. Our first goal was to determine if the performance of the tVOR improves when head translations are combined with head rotations in ambient lighting. A second goal was to measure tVOR during vertical head translations (bob), which has not received systematic study. We measured tVOR alone and in combination with the aVOR in 20 normal human subjects, aged 25-72 years, as they sat on a moving platform that bobbed at 2.0 Hz while rotating horizontally (yaw) at 1.0 Hz. When subjects viewed a visual target at 2 m, median "compensation gain" (eye rotational velocity/required eye rotational velocity to maintain foveal target fixation) was 0.52 during pure bob and 0.59 during combined bob-yaw; during viewing of a near target at approximately 17 cm, compensation gain was 0.58 for pure bob and 0.60 for combined bob-yaw. Mean phase lag of eye-in-head velocity for the tVOR was approximately 19 degrees with respect to the ideal compensatory response, irrespective of whether translation was accompanied by rotation. Thus, the tVOR changed only slightly during translation-rotation versus pure translation, and our subjects' ocular rotations remained at about 60% of those required to point the eyes at the target. Comparison of response during binocular or monocular viewing, and ambient or reduced illumination, indicated that relative image motion between the target and background was an important determinant of tVOR behavior. We postulate that tVOR evolved not to stabilize the image of the target on the fovea, but rather to minimize retinal image motion between objects lying in different planes, in order to optimize motion parallax information.

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Ocular Responses to Head Rotations During Mirror Viewing

Cited by 7 publications

References 10 publications

Vestibular and non-vestibular contributions to eye movements that compensate for head rotations during viewing of near targets

Vestibular and non-vestibular contributions to eye movements that compensate for head rotations during viewing of near targets

Effects of visual fixation and convergence on periodic alternating nystagmus due to MS

Vestibulo-ocular responses to vertical translation in normal human subjects

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