A STUDY was made to determine the physiological effects of lesions in the intralaminar thalamic nuclei upon subthalamic dyskinesia in the monkey. This study was based upon seven rhesus monkeys taken from a larger series in which lesions in the subthalamic nucleus produced unequivocal choreoid activity of sufficient persistence and severity to be appropriate for physiological evaluation. In these animals attempts were made to destroy portions of the intralaminar thalamic nuclei by electrodes introduced along the course of the internal medullary lamina. Attempts were made to produce maximal lesions in the centromedian nucleus without destroying parts of the ventral lateral nucleus.
Lesions in five monkeys destroyed portions of the centromedian, paracentral, and central lateral nuclei. Because of the spatial disposition of the intralaminar nuclei, portions of the dorsomedial and ventral posterior medial nuclei frequently were concomitantly involved. This study indicates that localized lesions destroying parts of the intralaminar nuclei do