Activity of cat parietofrontal neurons during the performance of a voluntary movement.

The impulse activity of 227 neurons of field 5 was investigated in cats trained to complete a movement of the forepaw in response to a stimulus. The discharges of each of them were collected relative to three markers: the presentation of the conditional signal, the raising of the paw from a support, and pressing on a pedal. The reactions associated with the performance of the reflex were recorded in 224 neurons. The majority of the cells reacting to the stimulus generated a pronounced excitatory response even at the beginning of the movement, but were inhibited at the moment of the touching of the pedal. Sixty-seven percent of the neurons whose discharges were collected relative to the raising of the paw reacted prior to the appearance of the EMG response. The parietofrontal neurons were identified on the basis of the presence of an antidromic response to the stimulation of the motor cortex. The changes in the discharge frequency which were associated with the movement significantly more often anticipated the EMG response in the parietofrontal neurons as compared with non-parietofrontal cells (79.0 and 63.3%, respectively). The parietofrontal neurons reacted more actively to the conditional signal, light flashes, acoustic tone, and tactile stimulation as well. Their role in the triggering and unfolding of the program of a voluntary movement is discussed.