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.

Differential effects of acute and prolonged morphine withdrawal on motivational and goal-directed control over reward-seeking behavior

“…This conclusion is also supported by the context-specificity of the deficit observed after brief morphine re-exposure, which was only apparent when rats were tested in the morphine-paired context. Interestingly, similar context-specific deficits in reward devaluation sensitivity have been observed when rats are tested in the presence of cues that predict other salient stimuli including alcohol [55], methamphetamine [77], or unrestricted access to highly-palatable junk foods [82]. Together, such findings suggest that affectively-charged environmental cues can perturb the cognitive processes responsible for goal-directed action selection.…”

Junk Food Exposure Disrupts Selection of Food-Seeking Actions in Rats

“…It is perhaps surprising that this aspect of decision-making is compromised following a simple change in diet given that rats exposed chronically to cocaine show relatively normal sensitivity to outcome devaluation on this same goal-directed action selection task ( 46 ). It may be that experiences consuming junk foods are particularly relevant and, therefore, have a lasting impact on how we decide which foods are worth pursuing.…”

“…We suggest that the tendency for junk-food diets to disrupt action selection for food reward may result from diet-related learning rather than a permanent and unconditional cognitive impairment. For instance, there is growing evidence that rats' capacity for goal-directed action selection for food rewards is acutely disrupted in the presence of contextual cues that signal access to junk food ( 46 ), an effect that has also been shown with drug-paired cues [either methamphetamine ( 47 ) or alcohol ( 48 )]. Thus, it is possible that rats given extensive junk-food exposure acquired a persistent—and perhaps less cue-dependent—expectation of having access to junk food, and that this influenced the way they made decisions about other food-seeking actions.…”

Making and breaking habits: Revisiting the definitions and behavioral factors that influence habits in animals

“…Further support for the context‐dependent nature of habits comes from work showing that training for habitual responding in one context does not interfere with goal‐directed responding in another context regardless of whether the two contexts differed according to length of training (3 vs. 12 sessions, experienced sequentially) or schedule of reinforcement (RR vs. RI, experienced concurrently; Gremel & Costa, 2013; Steinfeld & Bouton, 2021). Additional evidence of context specificity comes from work showing that food responding becomes habitual in the presence of contextual cues paired with alcohol or junk food, while being goal directed in the presence of control contextual cues (Kendig et al, 2016; Ostlund et al, 2010). In sum, these data indicate that habitual learning is context dependent and that new contexts trigger a transition to goal‐directed responding.…”