[Effect of microiontophoretic application of serotonin on the background impulse activity of visual cortex neurons in unanesthetized cats].

Sustained spike activity of neurones in the visual area (field 17) of the cerebral cortex and its changes induced by microionophoresis of serotonin was studied in experiments on unanaesthetized cats immobilized with diplacine. Neurones of field 17 with sustained activity are characterized by non-rhythmic, low-frequency discharges of a mixed type. 55 per cent of the studied neurones were sensitive to serotonin. They exhibited excitatory, inhibitory and phasic responses. The points discussed are: the importance of intracortical interactions between neurones in mechanisms of generation of their sustained spike activity, and the possible ;nvolvement of serotonin in ;he neurochemical processes of synaptic transmission in the visual area of the cerebral cortex.