Role of the Supplementary Motor Area and the Right Premotor Cortex in the Coordination of Bimanual Finger Movements

TLDR

The study investigates which cortical regions are engaged during different types of bimanual finger movements to better understand the neural basis of bimanual coordination. Using 15O‑labeled water PET, the authors measured regional cerebral blood flow in right‑handed volunteers while performing acoustically paced mirror, parallel, and unimanual finger movements at 1 Hz and 2 Hz. They found that the posterior supplementary motor area and right dorsal premotor cortex were more active during parallel bimanual movements than during mirror or unimanual movements, indicating these areas support bimanual coordination.

Abstract

To obtain a better understanding of the cortical representation of bimanual coordination, we measured regional cerebral blood flow (rCBF) with 15O-labeled water and positron emission tomography (PET). To detect areas with changes of rCBF during bimanual finger movements of different characteristics, we studied 12 right-handed normal volunteers. A complete session consisted of three rest scans and six scans with acoustically paced (1 Hz) bimanual, mirror, or parallel sequential finger movements. Activation of the right dorsal premotor area (PMd) extending to the posterior supplementary motor area (SMA) was significantly stronger during the parallel movements than during the mirror sequential movements (p < 0.05, at cluster level with correction for multiple comparisons). To determine whether these cortical areas truly represented bimanual coordination, a different group of nine normal volunteers was studied with a different task. Subjects performed acoustically paced (2 Hz) abduction-adduction movements of the index finger, making right only, left only, and bimanual mirror and parallel movements. Activation of the posterior SMA and right PMd was significantly greater during the parallel movements than during the bimanual mirror movements or the unimanual movements of either hand (p < 0.01, with anatomical constraint). Thus, the posterior SMA and right PMd appear to be related to the bimanual coordination of finger movements.