DYNAMICS OF CORTICAL-NEURONS RESPONSIVENE SS TO REPEATED SEPARATE ACTIONS OF L-GLUTAMATE AND ACETYLCHOLINE

Comparative analysis of the probability, direction and magnitude of ch anges of the mean firing rates for the background and L-glutamate - (G lu) and acetylcholine - (ACh) induced activity of single sensorimotor cortical neurons of unanesthetized rats showed that more significant c hanges occured in reaction to the applications of Glu. Increases of Gl u-induced activity were more frequent than increases of ACh-induced ac tivity in the course of 20 microiontophoretic applications of the tran smitters. Declines of Glu-induced activity were more frequent and prof ound than those of ACh-induced activity as a result of 100 presentatio ns. Enhancements of the background activity occured usually between th e cellular responses to ACh, and its decreases were more specific duri ng successive separate Glu presentations. The different functional rol es of Glu and ACh in the dynamics of neuronal discharges in the course of learning are discussed.