There is growing evidence for the role of the insular cortex in various types of cravings, including food craving. Here, we used resting-state functional brain connectivity (FBC) to explore system-level dysfunctions in the brain of obese (OB) individuals and their correlations with the leptin levels. We first used hierarchical clustering to identify the brain regions whose altered functioning was consistently reported by neuroimaging studies on food perception in OB subjects. We found that a cluster centred in left anterior insula and overlying frontal operculum (AI/fO) was specifically associated with hyper-responsivity in OB. This cluster was then used as a seed for a seed-based FBC analysis in 10 OB and 11 normal weight controls matched for sex, age and education. The analysis implied the calculation of the functional correlations of each brain voxel with the seed along the resting state fMRI time series. OB patients, compared to the control group, showed hyper-connectivity between the left AI/fO and key regions of the reward system, such as the left medial orbitofrontal cortex (OFC), in addition to the bilateral parahippocampal gyri and the posterior cingulate gyrus; conversely, they exhibited hypo-connectivity between the seed and the left dorsolateral prefrontal cortex, a key region involved in inhibitory control (all Ps < .corrected for multiple comparisons). Finally, we found a substantial trend for a negative correlation between AI/fO-OFC hyper-connectivity and plasma levels of leptin (ρ = - .612, p = .06). Our results provide evidence for an imbalance between reward and inhibitory control systems in OB patients, which might be worsened by an altered response to food intake regulatory hormones (e.g., anorexigenic leptin), thus driving the overeating behavior. Moreover, our results suggest that the left AI could be a suitable target for drugs or neuro-modulatory treatment to recalibrate the FBC of a network involved in food intake, reward and cognitive control.


F. Devoto: None. A. Ferrulli: None. L. Zapparoli: None. R. Bonandrini: None. L. Sconfienza: None. G. Banfi: None. L. Luzi: Speaker's Bureau; Self; A. Menarini Diagnostics, AstraZeneca, Eli Lilly and Company. Research Support; Self; Gelesis. Consultant; Self; McKinsey & Company. Speaker's Bureau; Self; Menarini Group, Merck Sharp & Dohme Corp.. Research Support; Self; Novartis AG. Speaker's Bureau; Self; Novo Nordisk A/S. Research Support; Self; Sunstar Foundation. Speaker's Bureau; Self; Smith & Nephew. E. Paulesu: None.

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