Neural Correlates of Reward and Self-Regulation
This line of research investigates a putative shared neural architecture for the representation of different kinds of reward and top-down control mechanisms that underlie self-regulatory success and failure. This work is supported by research grants from the National Institute on Drug Abuse (NIDA), the National Institute on Alcohol Abuse and Alcoholism (NIAA) and the National Heart, Lung, and Blood Institute (NHLBI).
Specifically, we are investigating the neural response to material that is considered to be rewarding to different groups of people. For example, our work has demonstrated that viewing attractive, opposite-sex faces engages the nucleus accumbens (NAcc) and a lateral region of the orbitofrontal cortex (OFC) more so than viewing unattractive faces (Cloutier et al., 2008, JCN). These same brain regions are similarly responsive when restricted eaters (i.e., dieters) view images of food (Demos, Kelley, and Heatherton, 2011; Wagner et al., 2012; Wagner et al., 2013), when smokers view smoking cues (Wagner et al., 2011), and when avid users of online digital environments view images of virtual items that are judged to be desirable for their virtual avatar. Our studies 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.
More recently, we have demonstrated that cue-reactivity in reward regions predicts real world appetitive behavior. Demos, Heatherton, and Kelley (2012) demonstrated that individual differences in ventral striatum responses to food cues predicted subsequent weight gain in a six-month followup, and responses to images of erotic scenes predicted individual differences in sexual interest. These effects were domain specific. Food cue reactivity predicted subsequent weight gain but not sexual interest and vice versa. Lopez et al. (2014) extended this work using smartphone experience sampling technology and showed that reward activity in response to appetizing food images predicts giving in to everyday food desires.
Our most recent work demonstrates that reward activity to fast-food commercials can predict adiposity in adolescents (Rapuano et al., 2015). Interestingly, this reward-related activity to food commercials was accompanied by the additional recruitment of mouth-specific somatosensory-motor cortices—a finding that suggests the intriguing possibility that higher-adiposity adolescents mentally simulate eating behaviors and offers a potential neural mechanism for the formation and reinforcement of unhealthy eating habits that may hamper an individual’s ability lose weight later in life.
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. In our recent Annual Review of Neuroscience article (Kelley, Wagner, and Heatherton, 2015), we review the available neuroscientific evidence regarding self-regulation and its failures. At its core, self-regulation involves a critical balance between the strength of an impulse and an individual’s ability to inhibit the desired behavior. Although neuroimaging and patient studies provide consistent evidence regarding the reward aspects of impulses and desires, the neural mechanisms that underlie the capacity for control have eluded consensus, with various executive control regions implicated in different studies. We outline the necessary properties for a self-regulation control system and suggest that the use of resting-state functional connectivity (rs-fcMRI) analyses may be useful for understanding how people regulate their behavior and why they sometimes fail in their attempts. We have preliminary evidence that the integrity of rs-fcMRI systems related to reward and self-regulation is compromised for those with greater body weight and enhanced for those with highest aerobic capacity (Huckins et al., in prep). 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.