Neuroimaging studies of hunger and impulsivity

Impulsive decision-making is associated with enhanced sensitivity to immediate over delayed rewards. The medial prefrontal cortex (MPFC), the anterior cingulate cortex (ACC), and the insula are involved in evaluating rewards and making decisions. The current study used functional magnetic resonance imaging (fMRI) to examine impulsive decision-making when participants reported increasing levels of hunger and no change in hunger over the 2 hours prior to the scan. Scans were performed using a 3 Tesla Siemens Skyra scanner. A mixed group of healthy weight to obese subjects was separated into an increasing hunger group, and a no change in hunger group. Participants performed a delay discounting task during which they chose between a smaller immediately available reward and a larger delayed reward. fMRI data were analyzed using AFNI and focused on brain responses when participants selected the immediately available reward, delayed reward and the difference in brain responses between choosing the immediately available vs. the delayed reward. Preliminary results show differences in brain activations between subjects who reported increases in hunger compared to those who did not report changes in hunger levels, in the insula and MPFC when choosing the delayed reward, but no differential brain activations were found when choosing the immediately available reward. Overall, the MPFC and insula may be activating more to suppress the urge to select an immediate choice when participants are hungry. These results indicate that changes in hunger impact impulsive decision-making and have implications for the development of health interventions.