Neuropharmacological analysis of caudate-induced cortical inhibition.

The effects of cortical superfusion of various chemical agents on the inhibition of the discharge of cortical neurons evoked by caudate nucleus stimulation were studied in urethane anesthetized rats. The post-stimulus inhibition (PSI) was unaffected by cortical superfusion with bicuculline, 6-amino-methyl 3-methyl-4H, 1, 2, 6-benzothiadiazine-1, 1-diazidehydrochloride (TAG) and atropine. The PSI was readily and reversibly blocked by cortical superfusion or i.v. injection of strychnine independently of both strychnine capability of eliciting epileptiform activity, and of the degree of excitation produced by the drug. Two animals with poor or absent PSI showed appearance of PSI after glycine topical application. These data suggest that in the rat neocortex, glycine may mediate the inhibitory effect resulting from caudate stimulation.