Activity of 98 neurons of the parietal associative cortex (PAC) and 189 supposedly aminergic brainstem neurons (dopaminergic in the substantia nigra pans compacta, noradrenergic in the locus coeruleus region, and serotonergic in the raphe nuclei) was recorded in awake cats. The animals were trained to perform a voluntary movement (pressing a pedal) not earlier than at a certain prefixed time moment. More than half of the recorded units modified their activity before the movement initiation. The PAC neurons responded mostly within the interval of planning of the movement, while reactions of aminergic neurons were observed in the course of its initiation, which probably provides facilitation of the responses of cortical neurons. The pattern of responses was rather specific for each of the studied neuronal populations.