Suppression of cell firing in the substantia nigra by caudate nucleus stimulation

• Published in: Experimental neurology Vol. 37; no. 2; pp. 395 - 411
• Main Authors: McNair, J.L., Sutin, J., Tsubokawa, T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.1972
• Subjects: Anesthesia; Animals; Barbiturates; Cats; Caudate Nucleus - physiology; Electric Stimulation; Evoked Potentials; Globus Pallidus - physiology; Haplorhini; Male; Nerve Degeneration; Neural Inhibition; Neural Pathways - physiology; Substantia Nigra - physiology; Synaptic Transmission - drug effects; Thalamic Nuclei - physiology
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/0014-4886(72)90083-0

Cats anesthetized with barbiturates show a unique 8–12/sec continuous rhythmic activity in the subthalamic nucleus and ventral tegmental region which may be correlated with the “barbiturate tremor.” Pallidal stimulation inhibits subthalamic nucleus slow-wave and single-unit activity, while nigral stimulation produces a phasic discharge in subthalamic neurons. In contrast to pallidal stimulation, caudate stimulation does not inhibit the firing of subthalamic nucleus cells. In view of this and the action of the substantia nigra upon the subthalamic nucleus, we studied the effects of caudate activation upon extracellularly recorded single unit responses in the nigra of barbiturate-anesthetized cats. Fifty-one units were analyzed. Of these, 24 were localized to the tegmentum just above the substantia nigra, 25 in the nigra, and two in the cerebral peduncle. The predominant effect of single caudate stimuli was suppression of firing of nigral (95%) or tegmental (58%) cells for either 70 or 140 msec, or more. These effects were seen in both medial and lateral portions of the nigra, and at rostral and caudal levels of the nucleus. No short-latency spikes were seen in nigral cells following caudate stimulation, and only a few in units localized to the tegmentum. In the barbiturate anesthetized cat, caudate stimulation leads to a suppression of firing of cells throughout the substantia nigra.