These findings suggest that ghrelin effects in HIPP modulate connectivity with the insula, which processes interoception and might be relevant to LSG-induced reductions in appetite/anxiety. Role of LSG in PCC and its enhanced connectivity with DLPFC in improving self-regulation following LSG requires further investigation.

The "hunger" hormone ghrelin regulates food-intake and preference for high-calorie (HC) food through modulation of the mesocortico-limbic dopaminergic pathway. Laparoscopic sleeve gastrectomy (LSG) is an effective bariatric surgery to treat morbid obesity. We tested the hypothesis that LSG-induced reductions in appetite and total ghrelin levels in blood are associated with reduced prefrontal brain reactivity to food cues. A functional magnetic resonance imaging (fMRI) cue-reactivity task with HC and low-calorie (LC) food pictures was used to investigate brain reactivity in 22 obese participants tested before and one month after bariatric surgery (BS). Nineteen obese controls (Ctr) without surgery were also tested at baseline and one-month later. LSG significantly decreased (1) fasting plasma concentrations of total ghrelin, leptin and insulin, (2) craving for HC food, and (3) brain activation in the right dorsolateral prefrontal cortex (DLPFC) in response to HC vs. LC food cues (P FWE < 0.05). LSG-induced reduction in DLPFC activation to food cues were positively correlated with reduction in ghrelin levels and reduction in craving ratings for food. Psychophysiological interaction (PPI) connectivity analyses showed that the right DLPFC had stronger connectivity with the ventral anterior cingulate cortex (vACC) after LSG; and changes in BMI were negatively correlated with changes in connectivity between the right DLPFC and vACC in the LSG group only. These findings suggest that LSG-induced weightloss may be related to reductions in ghrelin, possibly leading to decreased food craving and hypothetically reducing DLPFC response to the HC food cues.

Obese individuals exhibit brain alterations of resting-state functional connectivity (RSFC) integrity of resting-state networks (RSNs) related to food intake. Bariatric surgery is currently the most effective treatment for combating morbid obesity. How bariatric surgery influences neurocircuitry is mostly unknown. Functional connectivity density (FCD) mapping was employed to calculate local (lFCD)/global (gFCD) voxelwise connectivity metrics in 22 obese participants who underwent functional magnetic resonance imaging before and 1 month after sleeve gastrectomy (SG), and in 19 obese controls (Ctr) without surgery but tested twice (baseline and 1-month later). Two factor (group, time) repeated measures ANOVA was used to assess main and interaction effects in lFCD/gFCD; regions of interest were identified for subsequent seed to voxel connectivity analyses to assess resting-state functional connectivity and to examine association with weight loss. Bariatric surgery significantly decreased lFCD in VMPFC, posterior cingulate cortex (PCC)/precuneus, and dorsal anterior cingulate cortex (dACC)/dorsomedial prefrontal cortex (DMPFC) and decreased gFCD in VMPFC, right dorsolateral prefrontal cortex (DLPFC) and right insula (p < .05). lFCD decreased in VMPFC and PCC/precuneus correlated with reduction in BMI after surgery. Seed to voxel connectivity analyses showed the VMPFC had stronger connectivity with left DLPFC and weaker connectivity with hippocampus/parahippocampus, and PCC/precuneus had stronger connectivity with right caudate and left DLPFC after surgery. Bariatric surgery significantly decreased FCD in regions involved in self-referential processing (VMPFC, DMPFC, dACC, and precuneus), and interoception (insula), and changes in VMPFC/precuneus were associated with reduction in BMI suggesting a role in improving control of eating behaviors following surgery.

Functional magnetic resonance imaging (fMRI) has been used to investigate sex‐related differences in brain abnormalities in patients with irritable bowel syndrome (IBS). Like IBS, women with functional constipation (FC) are 2.1 times as many as men. No study has been performed yet to examine sex‐related differences in brain activity and connectivity in patients with FC. Here, we employed resting‐state fMRI with amplitude of low‐frequency fluctuation (ALFF) to investigate brain functional differences in 51 patients with FC (34 females) and 52 healthy controls (34 females). Results showed abdominal pain and abdominal distension correlated with trait (TAI) and state (SAI) anxiety ratings in the female FC group, and abdominal distension correlated with sensation of incomplete evacuation in the male FC group. Two‐way ANOVA revealed sex effects on ALFF in precentral gyrus, thalamus, insula (INS), and orbital frontal cortex (OFC, PFWE < 0.05). Post hoc test showed that the female FC group had lower ALFF than males in these brain regions (P < 0.01), and ALFF in INS and OFC was correlated with abdominal pain and difficulty of defecation, respectively. Seed voxel correlation analysis showed that the female FC group had weaker connectivity than males between INS and lateral OFC (lOFC). INS‐lOFC connectivity was negatively correlated with the anxiety score in the female FC group and was negatively correlated with abdominal distension in the male FC group. These findings provide the first insight into sex‐related differences in patients with FC and highlight that INS and OFC play an important role in modulating the intrinsic functional connectivity of the resting brain network showing that this role is influenced by sex.

Obesity-related brain gray (GM) and white matter (WM) abnormalities have been reported in regions associated with food-intake control and cognitive-emotional regulation. Bariatric surgery (BS) is the most effective way to treat obesity and induce structural recovery of GM/WM density and WM integrity. It is unknown whether the surgery can promote structural changes in cortical morphometry along with weight-loss. Structural Magnetic Resonance Imaging and surface-based morphometry analysis were used to investigate BS-induced alterations of cortical morphometry in 22 obese participants who were tested before and one month post-BS, and in 21 obese controls (Ctr) without surgery who were tested twice (Baseline and One-month). Results showed that fasting plasma ghrelin, insulin, and leptin levels were significantly reduced post-BS (P < 0.001). Post-BS there were significant decreases in cortical thickness in the precuneus (P < 0.05) that were associated with decreases in BMI. There were also significant increases post-BS in cortical thickness in middle (MFG) and superior (SFG) frontal gyri, superior temporal gyrus (STG), insula and ventral anterior cingulate cortex (vACC); and in cortical volume in left postcentral gyrus (PostCen) and vACC (P < 0.05). Post-BS changes in SFG were associated with decreases in BMI. These findings suggest that structural changes in brain regions implicated in executive control and self-referential processing are associated with BS-induced weight-loss.