40-Hz oscillations during motor behavior in man.

40-Hz oscillations were measured during finger, toe and tongue movement using an electrode array of 56 electrodes over the pre and post central areas. Each movement was made 150 times in intervals of 12 s. The average power increase in narrow frequency bands between 8 and 40 Hz was then calculated and the topographical distribution studied. 40-Hz oscillations were only found contralateral over the hand area for finger movements, close to the vertex for toe movements and bilateral symmetrical for tongue movements. The maxima of the 40-Hz oscillations occurred before movement onset.