Neural Correlates of Reward
This line of research investigates a putative shared neural architecture for the representation of different kinds of reward. This work is in its early stages and is supported by research grants from the National Institute on Drug Abuse (NIDA) and the National Heart, Lung, and Blood Institute. Specifically, we are investigating the neural response to material that is considered to be rewarding to different groups of people. For example, our recent work has demonstrated that viewing attractive, opposite-sex faces engages the nucleus accumbens (NAcc) more so than viewing unattractive faces (Cloutier et al., 2008, JCN). This same brain region is similarly responsive when restricted eaters (i.e., dieters) view images of food (Demos, Kelley, and Heatherton, 2011, JCN), and, most recently, when avid users of online digital environments view images of virtual items that are judged to be desirable for their virtual avatar (Caudle et al., in prep).
Our study in dieters demonstrated further specificity in the NAcc such that reward-related activity in response to food cues was only evident following dietary restraint failures, and more recently, we have demonstrated that cue-reactivity in the NAcc predicts weight gain over a six-month period in first-year college students (Demos, Heatherton, and Kelley, submitted).
Although traditional fMRI is well-suited to capture momentary brain activity wedded to the presentation or consumption of rewarding stimuli, it struggles to capture more tonic aspects of self-regulation. Put simply, the capacity for self-regulation reflects on-going, well-established efforts to achieve personal goals, the temporal dynamics of which are difficult to measure using standard event-related fMRI paradigms. A key innovation in this line of research is the application of rs-fcMRI to the study of self-regulation failure. rs-fcMRI signal correlations reflect histories of co-activation across brain regions—a pattern of statistical coherence that arises throughout development and provides a measure of the long-term functional relatedness of brain regions. One network consistently identified in studies of resting-state functional connectivity is the fronto-parietal control network, which includes dorsolateral PFC, dorsal PFC, middle cingulate cortex, intraparietal sulcus, and inferior parietal lobule (Dosenbach et al., 2008). We have preliminary evidence that the integrity of this fronto-parietal network is compromised for those with greater body weight and enhanced for those with highest aerobic capacity (Huckins et al., in prep). These findings provide initial evidence that individual differences in the integrity of this network are crucial for the long-term success or failure of self-regulation. In future studies, we plan to use these innovative rs-fcMRI methods to assess self-regulatory outcomes across a range of appetitive and potentially addictive behaviors such as eating, sex, alcohol consumption, smoking, and excessive use of online digital environments. Towards this end, we have already collected over 500 subjects worth of resting-state data.