EVIDENCE FOR LATERAL PREMOTOR AND PARIETAL OVERACTIVITY IN PARKINSONS-DISEASE DURING SEQUENTIAL AND BIMANUAL MOVEMENTS - A PET STUDY

Patients with Parkinson's disease have great difficulty in performing sequential and bimanual movements. We used (H2O)-O-15 PET to study the regional cerebral blood flow associated with performance of sequentia l finger movements made unimanually and bimanually in a group of Parki nson's disease patients and a group of control volunteers. In controls , sequential finger movements led to activation of the contralateral m otor cortex and inferior parietal cortex (Brodmann area 40), the later al premotor cortex and bilateral supplementary motor area. No prefront al activation was seen. Sequential finger movements in the Parkinson's disease group were associated with a similar pattern of activation bu t there was relative impairment of activation in the mesial frontal an d prefrontal areas. A novel finding was the presence of relative overa ctivity in the lateral premotor and inferolateral parietal regions. We conclude that in Parkinson's disease there is a switch from the use o f striato-mesial frontal to parietal-lateral premotor circuits in orde r to facilitate performance of complex finger movements.