Unraveling Interoceptive Processing and Action Dynamics: Exploring Neural and Psychological Responses to Food Cues Using fMRI

Interoception, the perception of body signals, which is crucial for maintaining metabolic homeostasis, is asserted to play a vital role in obesity. Despite conceptual assumptions that impaired insular interoceptive processing contributes to overeating behaviors predominantly through modulating motor cortices, this link has not been extensively explored. Therefore, to further investigate neural mechanisms underlying insula-based interoceptive processing, this pre-registered (PMC9003175) study assessed blood oxygenation level-dependent (BOLD) responses via functional magnetic resonance tomography (fMRI) in 45 healthy participants (31 females/14 males, age 35.78 {+/-} 10 years, BMI 29.52 {+/-} 3.5 kg/m2) during a block-designed food cue reactivity task. Region of interest (insula) and whole brain voxel-wise correlation analyses explored neural correlates of visceral interoception. Furthermore, group factor analysis (GFA) unveiled coherence patterns between neural (fMRI) and psychological/behavioral measures. At the psychological level, self-reported hunger (P < 0.01, d = 0.82) and food craving (P < 0.01, d = 0.68) significantly increased, while craving control (P = 0.04, d = 0.37) decreased after cue exposure. Voxel-wise correlation analysis identified positive correlations (P < 0.01) between visceral interoception and activation of the precentral gyrus (PrG or motor cortex), insula, inferior frontal gyrus (IFG), posterior cingulate cortex (PCC), and superior parietal lobule (SPL). Moreover, altered functional connectivity dynamics were noted within the insula-PrG-IFG network during food cue exposure, with a significant reduction of IFG-PrG connections (P = 0.05). Interestingly, GFA identified a cross-unit latent factor across neural and psychological/behavioral measures. Overall, our findings indicate that altered interoceptive processing (insula activity), motor planning (motor cortex activity), and diminished inhibitory control (negative IFG-PrG connectivity) collectively contribute to food craving generation and potentially subsequent actions toward food consumption.