Contribution of the dentato-thalamo-cortical system to control of motor synergy.

Stimulation of the dentate nucleus in the chronically implanted baboon elicits both movements restricted to a single joint and also complex movements of several body segments. The complex movements correspond to precise but stereotyped coordinating activity. Two types of data reveal that the cerebello-thalamo-cortical system is concerned in the elaboration of complex movements. (1) Examination of cortical, pyramidal and muscle response latencies shows that the message might be transmitted by this pathway. (2) The complex movement which is produced by stimulation of a site in the dentate nucleus is similar to the sum of movements induced by stimulation of each cortical point receiving excitatory projection from this particular dentate focus.