Immediate neural responses of appetitive motives and its relationship with hedonic appetite and body weight as revealed by magnetoencephalography

BACKGROUND: We aimed to determine the brain areas related to food motivation and to examine individual variability using magnetoencephalography (MEG) during a fasted state. Correlation analysis was performed between MEG responses and the subscale and aggregated scores of the Power of Food Scale (PFS) and body mass index (BMI). MATERIAL/METHODS: Eight healthy, right-handed males [age, 29.0±10.4 years; BMI, 22.7±2.4 kg/m(2) (mean ±SD)] were enrolled. The MEG experiment consisted of 2 food sessions and 2 control sessions in an alternating and counterbalanced order. During the MEG recordings, participants viewed a set of food pictures (food session) or mosaic pictures (control session) projected on a screen. RESULTS: When participants viewed pictures of food items, we were able to estimate equivalent current dipoles (ECDs) in the insular cortex in all participants peaked approximately 300 ms after the onset of each picture presentation. When they viewed mosaic pictures, 1 of 8 participants exhibited corresponding ECDs. Of note, significant correlations were observed between the intensities of the MEG responses and the subscale scores of Factor 1 (food available) (r=0.846, P=0.008) and those of Factor 2 (food present) (r=0.875, P=0.004), the aggregated scores of PFS (r=0.820, P=0.013), and BMI (r=0.898, P=0.002). CONCLUSIONS: We demonstrated the involvement of the immediate neural responses of the insular cortex in individual differences in appetitive motivation. The signal intensities of the insular cortex were associated with self-awareness of appetitive motive.