[The dual nature of the participation of the raphe nucleus in regulating neuronal interaction in the rabbit cerebral cortex].

Electrical stimulation of the midbrain raphe nuclei has been studied for peculiarities of its effect on the efficiency of synaptic transmission in the visual cortex of restrained rabbits. Preliminary identification of monosynaptic connections was conducted by the method of cross interval histograms of two neurons recorded in one cortical microvolume. Two types of changes in the character of interneuronal relations were revealed under the raphe nuclei effect. The obtained data are discussed considering the double role of serotonin in the regulation of cortical synaptic processes: mediatory (due to classical synaptic contacts) and modulatory (due to serotonin-containing varicosities in the intercellular space).