SEQUENTIAL ACTIVATION OF SUPPLEMENTARY MOTOR AREA AND PRIMARY MOTOR CORTEX DURING SELF-PACED FINGER MOVEMENT AN HUMAN EVALUATED BY FUNCTIONAL

The 'Bereitschaftspotential' attributed to activation of the supplemen tary motor area (SMA) precedes the 'motor potential' of the primary mo tor cortex (M1) about 500-1000 ms during self-initiated movements. A m easurement procedure is reported to evaluate the sequence of hemodynam ic activation within both motor areas by functional magnetic resonance imaging (fMRI). The fMRI-data were averaged across multiple trials of single voluntary finger movements and analyzed with respect to the on set-time of signal increase. All participants showed a sequential hemo dynamic response with SMA preceding M1 activation. The mean latency be tween hemodynamic activation of SMA and M1 amounted to 0.8 s. These fi ndings suggest that the vascular response parallels the electrical eve nts and that a sufficient temporal resolution can be achieved by fMRI to detect sequential hemodynamic activation of functionally connected cortical areas. (C) 1997 Elsevier Science Ireland Ltd.