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Impaired modulation of the vestibulo-ocular reflex in Huntington's disease

Authors

  • Joanne Fielding BA, BSc(Hons),

    Corresponding author
    1. Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry, and Psychological Medicine, Clayton Campus, Monash University, Victoria, Australia
    2. Mental Health Research Institute, Parkville, Victoria, Australia
    • Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton Campus, Victoria 3800, Australia
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  • Nellie Georgiou-Karistianis BSc(Hons), PhD,

    1. Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry, and Psychological Medicine, Clayton Campus, Monash University, Victoria, Australia
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  • John Bradshaw PhD, DSc,

    1. Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry, and Psychological Medicine, Clayton Campus, Monash University, Victoria, Australia
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  • Lynette Millist BApSci,

    1. Mental Health Research Institute, Parkville, Victoria, Australia
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  • Andrew Churchyard BSc(Hons), MB.BS, FRACP, PhD,

    1. Department of Neurology, Monash Medical Center, Clayton, Victoria, Australia
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  • Edmond Chiu DPM, MRANZCP, FRANZCP, MB.BS,

    1. Huntington's Disease Clinic, St. Georges Hospital, Kew, Victoria, Australia
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  • Owen White MB, BS, MSc, PhD, FRACP

    1. Mental Health Research Institute, Parkville, Victoria, Australia
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Abstract

The vestibulo-ocular reflex (VOR) stabilizes gaze during movement, in conjunction with other afferent information: visual, proprioceptive, and somaesthetic. The reflex can either be augmented or suppressed, depending on visual requirements, and undergoes long-term adaptation to compensate for physical changes in the subject. Importantly, over relatively short periods of time, the VOR should function consistently under the same circumstances. This study examines VOR function in patients with Huntington's disease (HD), with a view to investigating cortical influences on the reflex. Horizontal eye movements were recorded in 9 patients with HD and 7 normal subjects, using the scleral search coil technique, in response to high frequency, unpredictable head rotations imposed manually. To establish base VOR function, recordings were made in darkness, without instruction, before and after wearing ×2 magnifying lenses for a period of 2 hours to adapt the reflex. Recordings were also made before adaptation, while fixating a stationary visual target (VOR augmentation), and while fixating a target moving with the head (VOR suppression). Although results suggest that the VOR is preserved in HD, with relatively normal gain values and appropriate augmentation and suppression of the reflex with visual input, patients were unable to adapt the VOR to altered visual conditions. This represents a novel finding in HD and suggests that cortical structures compromised in HD exert influences on the long-term adaptation of the VOR. © 2003 Movement Disorder Society

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