[Effect of micropolarization of cat brain structures on extinctive inhibition]

The influence of bipolar micropolarization (MCP) (in the range of 0.01--0.1 mca) of the midbrain reticular formation (RF), the dorsal hippocampus (HC) and the temporal cortex (TC) on conditioned behaviour in conditions of extinctive inhibition of an active avoidance reaction to an acoustic stimulus was studied on seven cats in a shuttle chamber. It was shown that: 1) MCP or RF and TC restores the semiextinct conditioned reflex, while MCP of HC deepens its extinction; 2) MCP of RF reduces the conditioned reflex latency, while MCP of HC and TC increases it; 3) during MCP of RF there is an increase in the number of intersignal spontaneous motor reactions and of reactions to surroundings, while during MCP of HC and TC their number decreases; 4) MCP of RF and TC produces no disinhibition, if the conditioned reflex is deeply extinguished. The influence of MCP on conditioned behaviour is regarded as a directed modulation of reproduction of the dominating traces of one of the two contesting temporary connections which determine the achievement or non-achievement of the motor reaction.