[Relationship between background and induced activity of cat auditory cortex neurons during elaboration of a defensive conditioned reflex to acoustic stimulation].

Using glass microelectrodes, the impulse activity of auditory cortex neurons was studied in chronic experiments on cats. It was shown that an increase in frequency of the background activity occurring in many neurons during conditioning was often observed prior to the appearance of conditioned motor reactions. Comparison of mean frequencies of the background activity and corresponding evoked activity shows, on the one hand, the nonlinear dependence between them and, on the other hand, the prevalence of activation reactions as compared with inhibitory ones. Some levels of background activity were distinguished corresponding to mean evoked activity frequency ranges. Background activity analysis performed prior to the presentation of the conditioned stimulus and after its cessation (aftereffect) shows that at stable conditioned reflex mean frequencies in these periods are close to each other.