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MRC Human Movement and Balance Unit (Section
of Neuro-Otology), The National Hospital for Neurology and Neurosurgery
and Physics Department (Biophysics), Imperial College, London, UK
Correspondence to: Dr A Bronstein, MRC Human Movement and Balance Unit, The National Hospital for Neurology and Neurosurgery, 8-11 Queen Square, London WC1N 3BG, UK.
Received 13 May 1997 and in revised form 1
April 1998;
Accepted 24 April
1998
OBJECTIVES
To investigate (1) the effects of loss
of vestibular function on spatiotemporal vision and (2) the mechanisms
which enable labyrinthine defective (LD) patients to adapt to oscillopsia.
METHODSVisual function and eye movements were
assessed in seven normal subjects and four LD patients with oscillopsia
due to absent vestibulo-ocular reflex. Temporal vision was assessed by
measurement of threshold sensitivity for detection of a target which
moved across a flickering, spatially uniform background field. Spatial vision was investigated by measurements of threshold sensitivity for
the detection of a target moving across a spatially modulated background in the form of square wave gratings. Velocity discrimination was assessed with drifting gratings. All measurements were made under
static conditions and during oscillatory movement of either the visual
stimulus or the subject (1 Hz, peak velocity 50°/s).
RESULTS
TEMPORAL RESPONSESNormal subjects and LD
patients exhibited similar responses while static and under body oscillation.
SPATIAL RESPONSESThe two groups achieved similar
results under static conditions but body oscillation reduced threshold
sensitivities and shifted the spatial response function towards lower
spatial frequencies in the LD patients only. Similar changes in the
spatial responses were seen during oscillation of the visual stimulus
but these occurred in both normal subjects and LD patients.
VELOCITY DISCRIMINATIONTwo LD patients achieved
normal velocity discrimination but the other two showed abnormal
responses to visual stimulus movement; one displayed a loss of velocity
discrimination during whole body oscillation, and the other mismatched
the velocity of two moving grating stimuli.
CONCLUSIONSThe changes in the spatial
responses are attributed to the presence of retinal slip during visual
stimulus motion in all subjects or body oscillation in the LD patients.
It is concluded that any visual adaptation to oscillopsia achieved by
the LD patients does not influence the measured spatial response
functions, which arise at an early stage of visual processing. The
abnormal velocity discrimination may relate to the progressive
improvement in oscillopsia reported by LD patients.
This article has been cited by other articles:
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  A. Deutschlander, K. Hufner, R. Kalla, T. Stephan, T. Dera, S. Glasauer, M. Wiesmann, M. Strupp, and T. Brandt Unilateral vestibular failure suppresses cortical visual motion processing Brain, April 1, 2008; 131(4): 1025 - 1034. [Abstract] [Full Text] [PDF]
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E. A. Grunfeld, A. B. Morland, A. M. Bronstein, and M. A. Gresty Adaptation to oscillopsia: A psychophysical and questionnaire investigation Brain, February 1, 2000; 123(2): 277 - 290. [Abstract] [Full Text] [PDF]
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