[The relationship between achievement of a simple movement and changes in the individual components of an evoked...

Various moments of preparation and performance of a simple voluntary movement were tested in man with the aid of somatosensory, auditory, and visual evoked responses. An obvious attenuation of somatosensory responses closely related to the movement but independent of the spontaneous EEG changes and unaffected by the ischaemic deafferentation of the active limb, was observed. The time course of the amplitude changes was different for separate components of the same evoked response. The evoked response to stimulation of the inactive limb and the auditory evoked response changed also, while the visual evoked response remained unchanged. The described changes cannot be explained by changes in the transmission via the specific pathways. The changes in the response early components are supposed to manifest facilitation or activation of the sensory-motor cortical neurons, and those of the late, generalized complex--a decrease in the ascending message from unspecific structures.