Disrupted topological organization of the frontal-mesolimbic network in obese patients
Neuroimaging studies have revealed brain functional abnormalities in frontal-mesolimbic regions in obesity. However, the effects of obesity on brain network topology remains largely unknown. In the current study, we employed resting-state functional magnetic resonance imaging and graph theory methods to investigate obesity-related changes in brain network topology in 26 obese patients and 28 normal weight subjects. Results revealed that the whole-brain networks of the two groups exhibited typical features of small-world topology. Obese patients showed significantly increased shortest path length (Lp) and decreased global efficiency (Eglob). Moreover, decreased nodal-degree/efficiency was found in frontal (medial orbitofrontal cortex-mOFC, rostral anterior cingulate cortex-rACC), striatal (caudate/nucleus accumbens) and limbic regions (insula, amygdala, hippocampus/parahippocampal gyrus) and thalamus in obese patients. Network-based statistics showed that a sub-network, composed of 31 nodes and 30 edges, was significantly disrupted in obese patients; 29 out of 30 connections were associated with the right rACC. In the obese group, Lp and Eglob were negatively correlated with body mass index (BMI, P < 0.005), and BMI was negatively correlated with nodal-degree/efficiency of the mOFC (P < 0.001). Findings suggest disruption of the small-world organization and a global reduction of integration of functional brain networks involving the right rACC in obesity and implicating the mOFC in mediating severity.
KeywordsBrain connectome Frontal-mesolimbic Obesity Resting-state fMRI
This work was supported by the National Natural Science Foundation of China under Grant Nos. 81271549, 81470816, 61431013, 81501543, 81730016, 81601563, 81371530, 81571751, and 81571753, National Clinical Research Center for Digestive Diseases, Xi’an, China under Grant No. 2015BAI13B07, and in part by the Intramural Research Program of the United States National Institute on Alcoholism and Alcohol Abuse, Z01AA3009 (DT, NDV, GJW).
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
Informed consent was obtained from all patients included in the study.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
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