The responses of neurons in the ventrolateral nucleus (VL) of the thalamus were studied in humans during performance of voluntary motor tests; recordings were made with microelectrodes during stereotaxic operations in patients with Parkinson's disease. Two previously classified types of polyvalent neurons (A, B) were found to show different patterns of responses during the functional stages of carrying out a voluntary movement (preparation, initiation, performance). A and B neurons showed concordant changes in the dynamics of ongoing network activity in the form of linked (activation-inhibition) and synergic (activation) response patterns, correlating with the preparation-trigger and performance phases of movements. It is suggested that the simultaneous activity of both types of neuron, with their common functional nature, reflects integrative processes occurring in the ventrolateral nucleus and associated with programming and processing of general signal parameters but not with the performance of any particular movement. The anterior (Voa nucleus) and posterior (Vop) parts of the ventrolateral nucleus were found to have different roles in organizing voluntary movements, associated with differences in their cellular organization and mechanisms of transmitting motor signals. It is suggested that the concordant changes in the activities of the two types of neurons in these areas seen during the performance of voluntary movements gives the ventrolateral nucleus a key role in the motor control system in humans.