Associative mechanisms underlying the function of satiety cues in the control of energy intake and appetitive behavior.

While previous research has identified a number of metabolic, neural, and hormonal events that could serve as potential satiety signals, the mechanisms that enable satiety signals to suppress food-seeking and eating behavior remain poorly specified. Here we investigate the idea that the inhibitory power of satiety signals is derived, at least in part, from their ability to signal that foods and food-related stimuli will not be followed by reinforcing postingestive consequences. Viewed in this way, the signaling relationship in which satiety cues are embedded defines what is known in Pavlovian conditioning as a "serial feature negative" (sFN) discrimination problem. In this problem a "negative feature" cue precedes the presentation of a "target" cue on trials without reinforcement. In contrast, the target is reinforced on trials when the negative feature cue is not presented. Satiety cues can be seen as paralleling the function of negative feature cues in that they signal when food-related target cues will be nonreinforced. We conducted two experiments with rats that assessed if satiety signals functioned like negative feature stimuli. Experiment 1 explicitly pretrained satiety cues as negative feature stimuli, irrelevant stimuli, or under conditions where their ability to serve as negative feature stimuli would be attenuated. Control by satiety cues was highly sensitive to these experimental contingencies, with the best performance exhibited by rats given sFN pretraining. This sFN pretraining also transferred to enhance performance during subsequent training on another sFN problem with both external and internal negative feature cues. We also found that discriminative control by satiety cues blocked the development of that control by external cues. Experiment 2 evaluated whether a manipulation known to impair sFN performance with external negative feature cues (i.e., maintenance on a western diet) would also impair sFN performance when satiety cues were trained as negative feature stimuli. The results showed that compared to standard chow, WD intake impaired sFN performance similarly with both types of stimuli. These experiments provide evidence that an associative mechanism, like that underlying sFN performance, is involved with the control of appetitive behavior by satiety cues.