Food cue reactivity in successful laparoscopic gastric banding: A sham-deflation-controlled pilot study.

Laparoscopic adjustable gastric banding (LAGB) offers a unique opportunity to examine the underlying neuronal mechanisms of surgically assisted weight loss due to its instant, non-invasive, adjustable nature. Six participants with stable excess weight loss (%EWL ≥ 45) completed 2 days of fMRI scanning 1.5-5 years after LAGB surgery. In a within-subject randomized sham-controlled design, participants underwent (sham) removal of ∼ 50% of the band's fluid. Compared to sham-deflation (i.e., normal band constriction) of the band, in the deflation condition (i.e., decreasing restriction) participants showed significantly lower activation in the anterior (para)cingulate, angular gyrus, lateral occipital cortex, and frontal cortex in response to food images (p < 0.05, whole brain TFCE-based FWE corrected). Higher activation in the deflation condition was seen in the fusiform gyrus, inferior temporal gyrus, lingual gyrus, lateral occipital cortex. The findings of this within-subject randomized controlled pilot study suggest that constriction of the stomach through LAGB may indirectly alter brain activation in response to food cues. These neuronal changes may underlie changes in food craving and food preference that support sustained post-surgical weight-loss. Despite the small sample size, this is in agreement with and adds to the growing literature of post-bariatric surgery changes in behavior and control regions.

Increased Functional Connectivity Between Ventral Attention and Default Mode Networks in Adolescents With Bulimia Nervosa.

OBJECTIVE: Bulimia nervosa (BN) is characterized by excessive attention to self and specifically to body shape and weight, but the ventral attention (VAN) and default mode (DMN) networks that support attentional and self-referential processes are understudied in BN. This study assessed whether altered functional connectivity within and between these networks contributes to such excessive concerns in adolescents with BN early the course of the disorder. METHOD: Resting-state functional magnetic resonance images were acquired from 33 adolescents with BN and 37 healthy control adolescents (12-21 years) group matched by age and body mass index. Region-of-interest analyses were performed to examine group differences in functional connectivity within and between the VAN and DMN. In addition associations of VAN-DMN connectivity with BN symptoms, body shape/weight concerns, and sustained attention were explored using the Continuous Performance Test (CPT). RESULTS: Compared with control adolescents, those with BN showed significantly increased positive connectivity between the right ventral supramarginal gyrus and all DMN regions and between the right ventrolateral prefrontal cortex and the left lateral parietal cortex. Within-network connectivity did not differ between groups. VAN-DMN connectivity was associated with BN severity and body shape/weight concerns in the BN group. No significant group-by-CPT interactions on VAN-DMN connectivity were detected. CONCLUSION: Increased positive VAN-DMN connectivity in adolescents with BN could reflect abnormal engagement of VAN-mediated attentional processes at rest, perhaps related to their excessive attention to self-referential thoughts about body shape/weight. Future studies should further investigate these circuits as targets for the development of early interventions aimed at decreasing excessive body shape/weight concerns.