[Conditioned reactions of the neurons of the dorsal region of the hippocampus to a combination of sound and extracellular polarization].

Neuronal responses were recorded in the dorsal part of the rabbit hippocampus to a, aperiodical (45 units) and b, periodical (25 units) presentations of combinations of a sound and a DC pulse (anode, 0,1-2,0 na) acting through the recording microelectrode. In the group (a) identified conditioned responses to a former indifferent acoustic stimulus were elaborated in 22% of the neurones. More than a half of them produced differentiation and extinction. Differences were revealed between conditioned reactions and responses in pseudoconditioning tests. In the group (b) 30% of units elaborated a conditioned reaction to time. Activation type reactions were predominant. They appeared when the stimuli were omitted, and sometimes they emerged in 12 or more successive omissions.