Distribution of the cortical potentials associated with voluntary finger movements in man.

EEG recordings obtained prior to, during and after voluntary muscular contractions in right- and left-handers were analysed by the summation method. This technique makes it possible to record electrophysiological correlates of the preparation, initiation and execution of voluntary movement. The apparent differences in lateral distribution of the N1 and N2 component centrally reflect fundamentally different cortical processes associated with preparatory and execution of voluntary movement. On the whole, these findings fit the known fact that hemispherical lateralisation is more pronounced in right-handers, in this case in one of the paired motor systems. Left-handers exhibit less intra-hemispheric focalization of cerebral motor functions. The distribution pattern of both negative wave parietally is in agreement with the bilateral organisation of the parietal cortex. The anterior-posterior distribution of N1 and N2 (steeper anterior than posterior gradients were obtained) indicates a close co-operation between the central motor and the parietal sensitive areas.