Sign- vs. goal-tracking is associated with greater adiposity and altered functional connectivity in response to a naturalistic food paradigm

Our modern food environment is full of highly palatable, ultra-processed foods that influence our eating behaviors. The reinforcement learning framework posits that some individuals readily assign motivational value to environmental cues (e.g., food ads) that predict reward, biasing their attention and making them more susceptible to seek that reward. These individuals are characterized as sign-trackers and differ from goal-trackers who do not tend to assign any motivational value to those reward-predicting environmental cues. Here, we tested whether this well-characterized phenotype in animals that is commonly associated with increased impulsivity and substance use disorders, could be translated to humans and adapted to study differences in adiposity and eating behaviors. A total of 47 adults completed a food-adapted Pavlovian conditioning task with cues predicting the delivery of candy with simultaneous eye-tracking to determine the sign-tracking vs. goal-tracking phenotype. Participants also completed a naturalistic fMRI scan where they passively viewed videos of sweet and savory dishes to examine functional connectivity associated with those phenotypes. We found that sign-tracking behavior was associated with a greater waist-to-hip ratio but not BMI. During the viewing of the sweet video only, we identified a brain network comprising high-degree nodes in the fusiform gyrus, occipital lobe, prefrontal cortex and posterior cingulate cortex that predicted higher sign-tracking behavior. These findings suggest that the sign- and goal-tracking phenotype model translates to humans using a food-based eye-tracking methodology. Further, supported by animal research, sign-tracking is associated with greater central adiposity and greater functional connectivity between visual, sensorimotor, and subcortical networks.