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This Article Full Text Full Text (PDF) All Versions of this Article: 99/3/1354    most recent 01214.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bunday, K. L. Articles by Bronstein, A. M. PubMed PubMed Citation Articles by Bunday, K. L. Articles by Bronstein, A. M.

Visuo-vestibular Influences on the Moving Platform Locomotor Aftereffect

Neuro-Otology Unit, Department of Clinical Neuroscience, Division of Neuroscience and Mental Health, Imperial College London, Charing Cross Hospital, London, United Kingdom

Submitted 31 October 2007; accepted in final form 7 January 2008

After walking onto a moving platform subjects experience a locomotor aftereffect (LAE), including a self-generated stumble, when walking again onto a stationary platform. Thus this LAE affords examination of the role of vestibular input during an internally generated postural challenge. The experiments involved walking onto the stationary sled (BEFORE trials), walking onto the moving sled (MOVING), and a second set of stationary trials (AFTER). We investigated 9 bilateral labyrinthine defective subjects (LDS) and 13 age-matched normal controls (NC) with eyes open. We repeated the experiment in 5 NC and 5 LDS but this time the AFTER trials were performed twice, first eyes closed and then on eye reopening. During MOVING trials, LDS were considerably unstable, thus confirming the established role of the vestibular system during externally imposed postural perturbations. During AFTER trials, both groups experienced an aftereffect with eyes open and closed, shown as higher approach gait velocity, a forward trunk overshoot, and increased leg EMG. However, there were no significant group differences due to the fact that stopping the forward trunk overshoot was accomplished by anticipatory EMG bursts. On eye reopening the aftereffect reemerged, significantly larger in LDS than that in NC. The lack of group differences in AFTER trials suggests that when facing internally generated postural perturbations, as in this adaptation process, the CNS relies less on vestibular feedback and more on anticipatory mechanisms. Reemergence of the aftereffect on eye reopening indicates the existence of a feedforward visuo-contextual mechanism for locomotor learning, which is adaptively enhanced in the absence of vestibular function.