[Reversal of signal significance of stimuli in the avoidance reflex]

The course of reversal learning in go -- no go avoidance reflex differentiation in both cats and dogs was analysed in terms of interrelations between drive and instrumental reflex activity. When signalling properties of the conditioned stimuli were reversed, marked changes in the drive state of experimental animals occurred. The increase of the fear drive influenced both the transfer of the instrumental response to the new positive conditioned stimulus and the extinction of the response to the previously positive stimulus. The quality of the conditioned stimuli and their reflexogenic strength exerted clear effects on the fear drive and on the course of reversal learning. Prefrontal lesions affected the drive state and the conditioned reflex activity of the animals during the reversal learning.