title: Contexts Paired with Junk Food Impair Goal-Directed Behavior in Rats: Implications for Decision Making in Obesogenic Environments.
abstract: The high prevalence of obesity and related metabolic diseases calls for greater understanding of the factors that drive excess energy intake. Calorie-dense palatable foods are readily available and often are paired with highly salient environmental cues. These cues can trigger food-seeking and consumption in the absence of hunger. Here we examined the effects of palatable food-paired environmental cues on control of instrumental food-seeking behavior. In Experiment 1, adult male rats received exposures to one context containing three "junk" foods (JFs context) and another containing chow (Chow context). Next, rats were food-deprived and trained to perform instrumental responses (lever-press) for two novel food rewards in a third, distinct context. Contextual influences on flexible control of food-seeking behavior were then assessed by outcome devaluation tests held in the JF, chow and training contexts. Devaluation was achieved using specific satiety and test order was counterbalanced. Rats exhibited goal-directed control over behavior when tested in the training and chow-paired contexts. Notably, performance was habitual (insensitive to devaluation) when tested in the JF context. In Experiment 2 we tested whether the impairment found in the JF context could be ameliorated by the presentation of a discrete auditory cue paired with the chow context, relative to a second cue paired with the JF context. Consistent with the results of Experiment 1, the devaluation effect was not significant when rats were tested in the JF context with the JF cue. However, presenting the chow cue increased the impact of the devaluation treatment leading to a robust devaluation effect. Further tests confirmed that performance in the chow context was goal-directed and that sensory-specific satiety in the JF context was intact. These results show that environments paired with palatable foods can impair goal-directed control over food-seeking behavior, but that this deficit was improved by a cue paired with chow. This has promising implications for assisting individuals in controlling their eating behavior in environments designed to dysregulate it.
authors.affiliation: School of Psychology, The University of Sydney Sydney, NSW, Australia.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kendig
authors.affiliation: School of Psychology, The University of Sydney Sydney, NSW, Australia.
authors.forename: Ambrose M K
authors.initials: AM
authors.lastname: Cheung
authors.affiliation: School of Psychology, The University of Sydney Sydney, NSW, Australia.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Raymond
authors.affiliation: School of Psychology, The University of Sydney Sydney, NSW, Australia.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Corbit
keywords: Pavlovian conditioning; context; habit; instrumental conditioning; junk food; rat; stimulus