Monkey pulvinar units related to motor activity and sensory response.

Single neuron activity in the pulvinar (Pu) was recorded in unanesthetized Macaca irus to investigate the sensory-motor role of this nucleus. A cylinder cemented to the skull allowed microelectrode penetrations. The head was immobilized during recording. Animals were trained to move a lever (push-pull). Electromyographs (EMGs) of several limb muscles were recorded together with Pu unit activity. The effect of active and passive limb movements was studied. Pu responses were also recorded during stimulation with flashes and clicks. A high percentage of units (65%) modified their discharge rate with limb movements. Firings showed a rate modulation in relation to specified movement phases, which were characteristic of each individual unit. Firing rates correlated with movement parameters, strongly with velocity and amplitude, and less with force. Firing rate modulation depth correlated better than mean rate changes with movement parameters, implying that dynamic information is well represented while static parameters are less important. Most of the movement-related units showed visual or auditory responses. A visuo-auditory and motor response was demonstrated in a few cells. The results suggest a participation of the Pu in motor-control.