THE LEARNED FUNCTION OF FOOD-DEPRIVATION CUES - A ROLE FOR CONDITIONED MODULATION

Rats trained in one context to use stimuli arising from food deprivati on as discriminative signals for shock were tested in other contexts t o assess the basis of conditioned responding (i.e., freezing or behavi oral immobility). In Experiment 1, discriminative control by 24-h food -deprivation cues failed to promote transfer responding in a test cont ext that had no association with shock. This indicated that food depri vation cues had little direct excitatory power. However, transfer of b ehavioral control by 24-h food-deprivation cues was obtained in a cont ext paired with shock only when the rats were 19 h water deprived. Thi s finding agrees with the idea that food-deprivation cues become condi tioned modulators of the capacity of external stimuli to activate thei r association with an unconditioned stimulus. In Experiment 2, rats tr ained to use 24-h food-deprivation cues as signals for shock exhibited significantly greater transfer performance when the transfer context had undergone partial extinction relative to when the transfer context had undergone only simple excitatory training. This finding with depr ivation cues and transfer contexts (1) paralleled earlier results obta ined with discrete (auditory and visual) conditioned modulators and tr ansfer targets, and (2) posed difficulties for associative summation a nd generalization interpretations of transfer performance.