The Effect of High-Fat Diet on Extinction and Renewal

Diets high in saturated fats are linked to health problems and impairments in cognitive function in humans. Recent evidence suggests that exposure to a high-fat diet can impair rats' ability to appropriately inhibit responding to stimuli that are reinforced in some circumstances but not in others. Here, we examined the effects of exposure to a high-fat diet on the context-specific renewal of extinguished responding. Rats first received pairings of a noise stimulus with a food reinforcer. After 14 days of exclusive access to either a high-fat or a matched control diet, rats received nonreinforced presentations (extinction) of the noise in either the same context in which they were trained or a different context. Finally, responding to the noise was evaluated in the original training context in all rats. In control rats, substantial renewal was observed; that is, responding was greater if extinction was conducted in a context different from that of training and testing. Renewal was significantly less robust in rats fed the high-fat diet despite evidence that they were at least as sensitive to context change as control rats. Implications of these results for models of relapse and treatments for phobias, addiction, and overeating are discussed.