Conditioned blink reflex and neuronal activity in the auditory cortex of the cat.

The present study is concerned with conditioned reflex changes in background and evoked activity of the neuronal population of the auditory cortex (AI) in three waking cats. For the elaboration of a conditioned blink reflex, a series of eight clicks was used as the signal. The unconditional stimulus was rhythmic blowing of air at the eye. During the elaboration of a positive conditioned reflex there was a significant increase in the level of background activity. During conditioned reflex extinction, background activity showed a further increase. When extinguishing inhibition became profound, it was equivalent to sleep, and there was a strong fall in the level of background activity. During the restoration of an extinguished conditioned reflex, background activity fell to the level observed during conditioned reflex extinction, at the stage of consolidation. Application of an acoustic stimulus elicited a general, sometimes a slight increase in the number of spike discharges. Within the range of 300-350 ms - the time of appearance of the evoked response - neuronal activity underwent a reorganization, sometimes with a tendency to phasic variations. Phasic variations of the given population in response to sound were observed at all stages of the study.