A medial to lateral shift in pre-movement cortical activity in hemi-Parkinson's disease

Objective: Recent evidence suggests that cortical activity associated with voluntary movement is relatively shifted from medial to lateral premotor ar eas in Parkinson's disease. This shift occurs bilaterally even for unilater al responses. It is not clear whether the shift in processing reflects an o verall change in movement strategy, thereby involving alternate cortical ar eas, or reflects a compensatory change whereby, given the appropriate condi tions, less impaired cortical areas are able to provide a similar function in compensation for those areas which are more impaired. This issue was exa mined in patients with hemi-Parkinson's disease, in whom basal ganglia impa irment is most pronounced in one hemisphere. Methods: Fourteen patients with hemi-Parkinson's disease and 15 age-matched control subjects performed a Go/NoGo finger movement task and the continge nt negative variation (CNV) was recorded from 21 scalp positions. Results and conclusions: Maximal CNV amplitudes were found over central med ial regions for control subjects, but were shifted more frontally for Parki nson's disease patients, reduced in amplitude over the midline and laterali zed towards the side ipsilateral to the greatest basal ganglia impairment. This shift in cortical activity from medial to lateral areas in Parkinson's disease patients appears to reflect a compensatory mechanism operating pre dominantly on the side of greatest basal ganglia impairment. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.