Bilateral neuromagnetic activation of human primary sensorimotor cortex inpreparation and execution of unilateral voluntary finger movements

Extracranial magnetoencephalographic activity was separately recorded (25 c hannels) from bilateral primary sensorimotor cortex (M1-S1) of normal right -handers during unilateral finger movements. Standard dipole analysis indic ated only a contralateral M1-S1 source for first movement-evoked field (MEF 1) peaking at about 115 ms after electromyographic onset. However, the subt raction of the magnetic field generated by this source from the recorded ma gnetic field disclosed a low-amplitude ipsilateral central-parietal MEF1 th at was explained by an ipsilateral M1-S1 source. (C) 1999 Published by Else vier Science B.V. All rights reserved.