Conditional control of freezing by food deprivation intensity stimuli in pavlovian conditioning procedures

The potential of food deprivation intensity stimuli to acquire conditional control over freezing was investigated using four different classical conditioning procedures. In Experiment 1, rats were consistently shocked in a training box under one level of food deprivation and not shocked under a different food deprivation level. In Experiment 2, rats received a single shock under one of two different food deprivation levels, whereas in Experiment 3, animals were first preexposed to a training box under one deprivation level and then received a single shock under a different deprivation level. Finally, in Experiment 4, rats received a single shock under a specific food deprivation level, followed by extinction sessions under a different level. In each experiment, the effect of food deprivation intensity stimuli on conditioned freezing was subsequently assessed in nonreinforced tests under each of two deprivation levels. In Experiment 2, a high deprivation level during testing reduced freezing, regardless of whether the shock had occurred under a high or a low deprivation level. In Experiments 1, 3, and 4, rats that during training had received the nonshock sessions under a high deprivation level and the shock session(s) under a low level showed less freezing under the high level than under the low level. The results were discussed in terms of the joint operation of associative and nonassociative stimulus effects of food deprivation intensity cues on conditioned freezing.