[Neuronal interactions in the auditory cortex of the alert cat]

Background activity of neighbouring neurons was recorded during chronic experiments in auditory cortex of unanesthetized unimmobilized cats. Functional connection between simultaneously observed neurons was estimated by cross-correlation of the spike trains. 20 pairs of neurons were studied. The most frequent type of interaction (50%) was a "shared excitatory input" from specific auditory afferents. Interaction of the "shared inhibitory input" type (5%) and complex patterns of interactions were found. No interaction between cells was observed in 10% of cases. Direct inhibitory influence of a cell on a neighbouring one was not found at all. Probable reasons of absence of direct inhibitory interactions between auditory cortical neurons are discussed. Low level of background activity in inhibitory neurons is regarded to be possible.