Statistical probability mapping reveals high-frequency magnetoencephalographic activity in supplementary motor area during self-paced finger movements

Investigations of both haemodynamic and electroencephalographic measures of brain activity have demonstrated supplementary motor area (SMA) involvemen t in self-paced finger movements. in contrast, analysis of magnetoencephalo graphic (MEG) signals in the time domain has usually failed to detect SMA a ctivity in healthy individuals. We investigated oscillatory MEG activity in 12 normal adults during (a) a self-paced, complex sequence of finger movem ents and (b) a simple finger opposition task paced externally by tactile st imuli presented to the contralateral thumb. Statistical probability mapping revealed enhanced non-phase-locked spectral amplitudes in the 22-28 Hz ran ge over bilateral frontal cortex during self-paced as compared to externall y cued finger movements. This activity may reflect recruitment of cell asse mblies in SMA during self-paced, complex movements. (C) 2000 Elsevier Scien ce Ireland Ltd. All rights reserved.