Direct current stimulation over V5 enhances visuomotor coordination
by improving motion perception in humans
A. Antal, M.A. Nitsche, W. Kruse, T.Z Kincses, K.-P. Hoffmann & W. Paulus
J.Cogn.Neurosci., 16:521-527, 2004
- The primary aim of this study was to determine the extent to which human MT+/V5, an extrastriate visual area
known to mediate motion processing, is involved in visuomotor coordination. To pursue this we increased or decreased the excitability of MT+/V5, primary motor, and primary visual cortex
by the application of 7 min of anodal and cathodal transcranial direct current stimulation (tDCS) in healthy human
subjects while they were performing a visuomotor tracking task involving hand movements. The percentage of correct
tracking movements increased specifically during and immediately after cathodal stimulation, which decreases cortical
excitability, only when V5 was stimulated. None of the other stimulation conditions affected visuomotor performance.
We propose that the improvement in performance caused by cathodal tDCS of V5 is due to a focusing effect on to
the complex motion perception conditions involved in this task. This hypothesis was proven by additional experiments:
Testing simple and complex motion perception in dot kinetograms, we found that a diminution in excitability induced
by cathodal stimulation improved the subject's perception of the direction of the coherent motion only if this
was presented among random dots (complex motion perception), and worsened it if only one motion direction was presented
(simple movement perception). Our data suggest that area V5 is critically involved in complex motion perception
and identification processes important for visuomotor coordination. The results also raise the possibility of the
usefulness of tDCS in rehabilitation strategies for neurological patients with visuomotor disorders.
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