Recording and stimulation of the ventralis intermedius nucleus of the human thalamus

Abstract

Extracellular recording of the spontaneous and evoked activity in and around the thalamic ventralis intermedius (V.i.m.) nucleus and electrical stimulation of the recorded point were performed on awake parkinsonian patients. In V.i.m., the neurons were found which responded to contralateral natural stimuli of kinesthetic origin. V.i.m. nucleus and its dorsal area were rich in spontaneous burst discharges, rhythmic and nonrhythmic, mostly independent from peripheral afferent inflow. When V.i.m. area was stimulated electrically (rectangular pulse of 0.5 msec, 60 Hz, 10V), weak intensity stimulation produced paresthetic sensation exactly in its peripheral receptive field, and stronger stimulation often resulted in complex movement of the contralateral upper limb around its receptive field, generally being predominant in extensor muscle.