FACILITATORY AND DEPRESSIVE EFFECTS OF IO NTOPHORETICALLY APPLIED ACETYLCHOLINE ON THE EARLY AND LATE COMPONENTS OF REACTIONS OF CAT MOTOR CORTEX NEURONS DURING PERFORMANCE OF CONDITIONED FOREPAW PLACING

The iontophoretic application of acetylcholine onto the motor cortex o f cats during the execution of conditioned placing reaction caused an increase in neuronal excitability and facilitation of ''extrinsic'' co nnections (manifested as an enhancement of primary responses to electr ical stimulation of the parietal cortex) and independent effect of sup presion, which could be seen only in the response components with long er latency, The functional significance of these oppositely directed e ffects of acetylcholine application is corroborated by statistically s ignificant changes in the motor response latency of the same direction s as the changes in neuronal responses. Such a correlation was observe d in a number of experiments.