Pallidal and entopeduncular intracellular responses to striatal, cortical, thalamic, and sensory inputs

Abstract

Intracellular recordings were made from pallidal and entopeduncular neurons in cats. Responses were evoked by direct brain stimulation and auditory and somatosensory stimuli. Brain sites stimulated were caudate nucleus, the precruciate area of the cerebral cortex, and the central median-parafascicular region of the thalamus. The predominant synaptic response pattern for all types of stimulation was an EPSP-IPSP sequence. Thirty percent of the responses were IPSPs only. Relatively few “pure” EPSPs were recorded. These patterns of synaptic responses were compared with those evoked by comparable stimuli to caudate neurons. In particular, the relatively high percentage of “pure” IPSPs in pallidal and entopeduncular cells contrasted with the rate occurrence of “pure” IPSPs in caudate neurons. This difference in incidence of response types may be attributed to anatomical differences in the fine structure of these nuclei.