Habenular connectivity predict weight loss and negative emotional-related eating behavior after laparoscopic sleeve gastrectomy.

Habenular (Hb) processes negative emotions that may drive compulsive food-intake. Its functional changes were reported following laparoscopic-sleeve-gastrectomy (LSG). However, structural connectivity (SC) of Hb-homeostatic/hedonic circuits after LSG remains unclear. We selected regions implicated in homeostatic/hedonic regulation that have anatomical connections with Hb as regions-of-interest (ROIs), and used diffusion-tensor-imaging with probabilistic tractography to calculate SC between Hb and these ROIs in 30 obese participants before LSG (PreLSG) and at 12-month post-LSG (PostLSG12) and 30 normal-weight controls. Three-factor-eating-questionnaire (TFEQ) and Dutch-eating-behavior-questionnaire (DEBQ) were used to assess eating behaviors. LSG significantly decreased weight, negative emotion, and improved self-reported eating behavior. LSG increased SC between the Hb and homeostatic/hedonic regions including hypothalamus (Hy), bilateral superior frontal gyri (SFG), left amygdala (AMY), and orbitofrontal cortex (OFC). TFEQ-hunger negatively correlated with SC of Hb-Hy at PostLSG12; and increased SC of Hb-Hy correlated with reduced depression and DEBQ-external eating. TFEQ-disinhibition negatively correlated with SC of Hb-bilateral SFG at PreLSG. Increased SC of Hb-left AMY correlated with reduced DEBQ-emotional eating. Higher percentage of total weight-loss negatively correlated with SC of Hb-left OFC at PreLSG. Enhanced SC of Hb-homeostatic/hedonic regulatory regions post-LSG may contribute to its beneficial effects in improving eating behaviors including negative emotional eating, and long-term weight-loss.

Long-term changes in insula-mesolimbic structural and functional connectivity in obese patients after laparoscopic sleeve gastrectomy.

OBJECTIVE: Brain imaging studies have shown insula-related functional and structural abnormalities in patients with obesity. Laparoscopic sleeve gastrectomy is currently an effective procedure for treating obesity, which promotes acute recovery of brain functional and structural abnormalities in obese patients. The aim of this study was to investigate the long-term impact of laparoscopic sleeve gastrectomy on insula-related structural and functional connectivity. METHODS: Diffusion tensor imaging and resting-state functional magnetic resonance imaging were employed to investigate laparoscopic sleeve gastrectomy-induced changes in insula-related structural connectivity and corresponding resting-state functional connectivity in 25 obese patients prior to (PreLSG) and 12 months post-surgery (PostLSG12). RESULTS: Results showed significant increases in fractional anisotropy and axial diffusivity between the right insula and anterior cingulate cortex, and higher fractional anisotropy of left insula-putamen, left insula-caudate and anterior cingulate cortex-right posterior cingulate cortex/precuneus at PostLSG12 compared with PreLSG. There were significant negative correlations between axial diffusivity of right insula-anterior cingulate cortex and body mass index, and fractional anisotropy of right insula-anterior cingulate cortex with scores on external eating at PostLSG12. Anxiety and depressive status ratings were negatively correlated with fractional anisotropy of left insula-putamen at PostLSG12. In addition, there was a significant decrease in resting-state functional connectivity between left insula and left caudate. CONCLUSIONS: These findings demonstrate long-term changes in insula-related structural and functional connectivity abnormalities promoted by laparoscopic sleeve gastrectomy, which highlight its strong association with long-term weight loss and improvement in eating behaviors.

Alterations in Functional and Structural Connectivity of Basal Ganglia Network in Patients with Obesity.

Obesity is related to overconsumption of high-calorie (HiCal) food, which is modulated by brain reward and inhibitory control circuitries. The basal ganglia (BG) are a key set of nuclei within the reward circuitry, but obesity-associated functional and structural abnormalities of BG have not been well studied. Resting-state functional MRI with independent component analysis (ICA) and probabilistic tractography were employed to investigate differences in BG-related functional-(FC) and structural connectivity (SC) between 32 patients with obesity (OB) and 35 normal-weight (NW) participants. Compared to NW, OB showed significantly lower FC strength in the caudate nucleus within the BG network, and seed-based FC analysis showed lower FC between caudate and dorsolateral prefrontal cortex (DLPFC), which was negatively correlated with craving for HiCal food cues. Further SC analysis revealed that OB showed lower SC than NW between left caudate and left DLPFC as measured with fractional anisotropy (FA). Alterations in FC and SC between caudate and DLPFC in obese patients, which highlights the role of BG network in modulating the balance between reward and inhibitory-control.

Brain structural changes in regions within the salience network in patients with functional constipation.

Functional constipation (FCon) is one of the common functional gastrointestinal disorders (FGID). Previous studies reported alterations in cortical morphometry as well as changes in white matter (WM) fiber tracts and thalamo-limbic/parietal structural connectivity (SC). However, whether patients with FCon are implicated in changes in gray matter (GM) volume and associated SC remains unclear. Voxel-based morphometry (VBM) was first employed to examine differences in GM volume between 48 patients with FCon and 52 healthy controls (HC). Diffusion tensor imaging (DTI) with probabilistic tractography analysis was then employed to explore alterations in SC of these regions. Results showed abdominal symptoms were positively correlated with anxiety (SAS). Two sample t-test showed patients with FCon had decreased GM volumes in the right middle frontal gyrus (MFG_R), left insula (INS_L), and anterior cingulate cortex (ACC, PFWE < 0.05) which were negatively correlated with abdominal symptoms and difficulty of defecation respectively. Seed-based SC analysis showed patients with FCon had decreased fractional anisotropy of the ACC-right MFG and bilateral INS-MFG tracts. These findings reflect FCon is associated with changes in GM volumes and corresponding SC in brain regions within the salience network.

White-matter microstructural alterations in patients with functional constipation: A tract-based spatial statistics study.

BACKGROUND: Highly prevalent functional constipation (FC) belongs to the category of functional gastrointestinal disorders. Neuroimaging studies have demonstrated brain functional and morphometric changes in patients with FC. However, whether FC is associated with white-matter (WM) microstructural alterations remains unclear. METHODS: Diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) were introduced to investigate WM microstructural changes as calculated by fractional anisotropy (FA), mean (MD), axial (AD), and radial diffusivity (RD) in 26 FC patients and 31 healthy controls. KEY RESULTS: Patients with FC relative to healthy controls had significantly decreased FA with increased MD/RD in the genu (GCC) and body (BCC) of the corpus callosum, right cingulum (Cing), bilateral anterior corona radiata (ACR), bilateral superior corona radiata (SCR), and left posterior corona radiata (PCR) (pFWE  < 0.05). Between-group difference was only in the left SCR and PCR when regressing out anxiety and depression as covariates. CONCLUSIONS AND INFERENCES: These WM tracts are mainly responsible for sensory and emotional information communication and corresponding functional integration; thus, our findings indicate an association between FC and WM microstructural abnormalities in regions involved with visceral afferent and emotional-arousal processing. Alterations in WM microstructures including the CC, cingulum, and ACR are more related to psychological symptoms than constipation, which might have greater impact on brain structures.

Habenular and mediodorsal thalamic connectivity predict persistent weight loss after laparoscopic sleeve gastrectomy.

OBJECTIVE: The aim of this study was to investigate laparoscopic sleeve gastrectomy (LSG)-induced changes in connectivity between regions involved with reward/antireward and cognitive control and the extent to which these changes persist after surgery and predict sustainable weight loss. METHODS: Whole-brain local functional connectivity density (lFCD) was studied in 25 participants with obesity who underwent resting-state functional MRI before (PreLSG), 1 month after (PostLSG1 ), and 12 months after (PostLSG12 ) LSG and compared with 25 normal-weight controls. Regions with significant time effects of LSG on functional connectivity density were identified for subsequent seed-based connectivity analyses and to examine associations with behavior. RESULTS: LSG significantly increased lFCD in the mediodorsal thalamic nucleus (MD) and in the habenula (Hb) at PostLSG12 compared with PreLSG/PostLSG1 , whereas it decreased lFCD in the posterior cingulate cortex/precuneus (PCC/PreCun) at PostLSG1 /PostLSG12 , and these changes were associated with reduction in BMI. In contrast, controls had no significant lFCD differences between baseline and repeated measures. MD had stronger connectivity with PreCun and Hb at PostLSG12 compared with PreLSG/PostLSG1 , and the increased MD-left PreCun and Hb-MD connectivity correlated with decreases in hunger and BMI, respectively. PCC/PreCun had stronger connectivity with the insula at PostLSG1-12 . CONCLUSIONS: The findings highlight the importance of reward and interoceptive regions as well as that of regions mediating negative emotions in the long-term therapeutic benefits of LSG.

Obese Individuals Show Disrupted Dynamic Functional Connectivity between Basal Ganglia and Salience Networks.

Previous functional magnetic resonance imaging (fMRI) studies have showed obesity (OB)-related alterations in intrinsic functional connectivity (FC) within and between different resting-state networks (RSNs). However, few studies have examined dynamic functional connectivity (DFC). Thus, we employed resting-state fMRI with independent component analysis (ICA) and DFC analysis to investigate the alterations in FC within and between RSNs in 56 individuals with OB and 46 normal-weight (NW) controls. ICA identified six RSNs, including basal ganglia (BG), salience network (SN), right executive control network/left executive control network, and anterior default-mode network (aDMN)/posterior default-mode network. The DFC analysis identified four FC states. OB compared with NW had more occurrences and a longer mean dwell time (MDT) in state 2 (positive connectivity of BG with other RSN) and also had higher FC of BG-SN in other states. Body mass index was positively correlated with MDT and FCs of BG-aDMN (state 2) and BG-SN (state 4). DFC analysis within more refined nodes of RSNs showed that OB had more occurrences and a longer MDT in state 1 in which caudate had positive connections with the other network nodes. The findings suggest an association between caudate-related and BG-related positive FC in OB, which was not revealed by traditional FC analysis, highlighting the utility of adding DFC to the more conventional methods.

Altered Functional Connectivity Within and Between Salience and Sensorimotor Networks in Patients With Functional Constipation.

Functional constipation (FCon) is a common functional gastrointestinal disorder. A considerable portion of patients with FCon is associated with anxiety/depressive status (FCAD). Previous neuroimaging studies mainly focused on patients with FCon without distinguishing FCAD from FCon patients without anxiety/depressive status (FCNAD). Differences in brain functions between these two subtypes remain unclear. Thus, we employed resting-state functional magnetic resonance imaging (RS-fMRI) and graph theory method to investigate differences in brain network connectivity and topology in 41 FCAD, 42 FCNAD, and 43 age- and gender-matched healthy controls (HCs). FCAD/FCNAD showed significantly lower normalized clustering coefficient and small-world-ness. Both groups showed altered nodal degree/efficiency mainly in the rostral anterior cingulate cortex (rACC), precentral gyrus (PreCen), supplementary motor area (SMA), and thalamus. In the FCAD group, nodal degree in the SMA was negatively correlated with difficulty of defecation, and abdominal pain was positively correlated with nodal degree/efficiency in the rACC, which had a lower within-module nodal degree. The salience network (SN) exhibited higher functional connectivity (FC) with the sensorimotor network (SMN) in FCAD/FCNAD, and FC between these two networks was negatively correlated with anxiety ratings in FCAD group. Additionally, FC of anterior insula (aINS)-rACC was only correlated with constipation symptom (i.e., abdominal pain) in the FCNAD group. In the FCAD group, FCs of dorsomedial prefrontal cortex-rACC, PreCen-aINS showed correlations with both constipation symptom (i.e., difficulty of defecation) and depressive status. These findings indicate the differences in FC of the SN-SMN between FCAD and FCNAD and provide neuroimaging evidence based on brain function, which portrays important clues for improving new treatment strategies.