[The effect of serotonin on the neuronal reactions of the sensorimotor cortex evoked by tactile and conditional acoustic stimulation].

Responses of the sensorimotor cortex neurons to tactile and conditional sound stimuli have been investigated before and after serotonin and lysergoamide iontophoretic application. Three functional neuronal groups were distinguished according to their responses to unconditional and conditional stimuli. It was shown that serotonin application facilitated early and late impulse responses to tactile stimuli, facilitated and modulated impulse responses of many cortical neurons to conditional stimuli. Changes in responses to conditioning occurred during initial phase of the placing reaction and just after initiation of the conditional movement. Serotonin application promoted involving new neurons in response to sound. All these changes in the reactions developed with unsignificant background activity fluctuation. It is supposed that facilitation of neuronal responses caused by serotonin was linked with activation of excitatory receptors (S2). An increase of the background and evoked impulse activity following application of lysergoamide may depend on inhibitory serotonin receptors (S1B).