Physiological properties of projection neurons in the monkey striatum to the globus pallidus.

In order to study neuronal information transfer from the striatum to the globus pallidus (GP) during voluntary movement, we recorded activity of electrophysiologically identified projection neurons in the putamen to the GP while the monkey was performing learned movement tasks. Two categories of putamen neurons were recorded: one with tonic spontaneous discharges at about 2-7 impulses/s responded to external sensory stimuli (type I); the other with very low spontaneous discharge rates less than 0.5 impulses/s showed phasic burst discharges which were time-locked to limb or orofacial movements (type II). All of the putamen neurons identified as projecting to the GP (external and/or internal segment) by an antidromic activation from electrical stimulation of the GP were type II cells. It was concluded that the movement-related activity of type II putamen neurons is transferred to GP and/or SN during voluntary movement but tonically active type I cells do not project to the GP.