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 insular interoceptive functioning contributes to obesity risk, predominantly through modulating motor cortices, this link has not been extensively explored. Therefore, to further investigate neural and psychological components underlying the processing of food cues with a specific focus on insula-based interoceptive processing, this 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 appetitive sensations. At the psychological level, appetitive sensations (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 subjective appetitive sensation 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 unveiled a cross-unit latent factor across neural and psychological/behavioral measures. Overall, our findings suggest that interoceptive processing in the insula with increased motor cortex activity, and diminished inhibitory control of IFG contribute to the enhancement of an appetitive state and possibly subsequent weight gain. Further research incorporating the consummatory phase may offer deeper insights into the neural mechanisms underlying the generation of action tendencies toward food consumption patterns.