Functional network centrality in obesity: A resting-state and task fMRI study Isabel García-García a,b , María Ángeles Jurado a,c,d,n , Maite Garolera d,e , Idoia Marqués-Iturria a,c , Annette Horstmann b,f , Bàrbara Segura a,d , Roser Pueyo a,c,d , María José Sender-Palacios g , Maria Vernet-Vernet g , Arno Villringer b , Carme Junqué a,d,h , Daniel S. Margulies i , Jane Neumann b,f a Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Passeig de la Vall d'Hebron, 171, 08035 Barcelona, Spain b Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany c Institute for Brain, Cognition and Behaviour (IR3C), University of Barcelona, Barcelona, Spain d Grup de Recerca Consolidat en Neuropsicologia (2014 SGR 98), Barcelona, Spain e Neuropsychology Unit, Hospital de Terrassa, Consorci Sanitari de Terrassa, Terrassa, Spain f IFB Adiposity Diseases, Leipzig University Medical Center, Leipzig, Germany g CAP Terrassa Nord, Consorci Sanitari de Terrassa, Terrassa, Spain h Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain i Max Planck Research Group for Neuroanatomy and Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany article info Article history: Received 1 August 2014 Received in revised form 3 February 2015 Accepted 28 May 2015 Available online 19 June 2015 Keywords: Body-mass index fMRI Functional connectivity Graph analysis Brain abstract Obesity is associated with structural and functional alterations in brain areas that are often functionally distinct and anatomically distant. This suggests that obesity is associated with differences in functional connectivity of regions distributed across the brain. However, studies addressing whole brain functional connectivity in obesity remain scarce. Here, we compared voxel-wise degree centrality and eigenvector centrality between participants with obesity (n ¼20) and normal-weight controls (n ¼21). We analyzed resting state and task-related fMRI data acquired from the same individuals. Relative to normal-weight controls, participants with obesity exhibited reduced degree centrality in the right middle frontal gyrus in the resting-state condition. During the task fMRI condition, obese participants exhibited less degree centrality in the left middle frontal gyrus and the lateral occipital cortex along with reduced eigenvector centrality in the lateral occipital cortex and occipital pole. Our results highlight the central role of the middle frontal gyrus in the pathophysiology of obesity, a structure involved in several brain circuits signaling attention, executive functions and motor functions. Additionally, our analysis suggests the existence of task-dependent reduced centrality in occipital areas; regions with a role in perceptual processes and that are profoundly modulated by attention. & 2015 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Obesity is a chronic multifactorial health problem defined by excessive adiposity or body fat. Although obesity is not usually strictly considered a brain disorder, multiple lines of neurobiolo- gical research have revealed the existence of structural and functional brain alterations associated with obesity (Dagher, 2012). Relative to normal-weight participants, obese populations exhibit lower gray matter volume, cortical thickness and glucose meta- bolism in the prefrontal cortex (Pannacciulli et al., 2006; Will- eumier et al., 2011; Marqués-Iturria et al., 2014). In striatal struc- tures, individuals with obesity seem to exhibit lower dopamine D2/D3 receptor availability (Wang et al., 2001; De Weijer et al., 2011; but see Eisenstein et al., 2013) and increased gray matter volume (Horstmann et al., 2011). Additionally, functional neuroi- maging studies have observed differences between participants with obesity and normal-weight controls during reward proces- sing. In response to food stimuli, participants with obesity ex- hibited higher activation of the parahippocampal gyrus/amygdala, putamen and superior frontal gyrus, along with lower activation of the insula and occipital areas (Nummenmaa et al., 2012; Brooks Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/psychresns Psychiatry Research: Neuroimaging http://dx.doi.org/10.1016/j.pscychresns.2015.05.017 0925-4927/& 2015 Elsevier Ireland Ltd. All rights reserved. Abbreviations: AFNI, Analysis of Functional Neuroimages; BMI, body-mass index; FSL, FMRIB Software Library; fMRI, functional magnetic resonance imaging; ICA, independent component analysis; SCID-I, Structured Clinical Interview for DSM-IV; SPM, statistical parametric mapping n Corresponding author at: Department of Psychiatry and Clinical Psychobiology, University of Barcelona, Passeig de la Vall d'Hebron, 171, 08035 Barcelona. Fax: þ34 93 402 15 84. E-mail address: majurado@ub.edu (M.Á. Jurado). Psychiatry Research: Neuroimaging 233 (2015) 331–338