Neuroimaging and neuromodulation approaches to study eating behavior and prevent and treat eating disorders and obesity

basal metabolism in and well as inparallel with increasedactivation of inresponsetopalat-ablefoodcues.Elevatedrewardregionresponsivitymaytriggerfoodcravingandpredictfutureweightgain.This studies using functional and molecular neuroimaging to early diagnostics andtophenotypesubjectsatriskbyexploringdifferentneurobehavioraldimensionsofthefoodchoicesandmo- tivationprocesses.Inthe functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), pharmacogenetic fMRI and functional near-infrared spectroscopy (fNIRS) will be discussed in the context of recent work dealing with eating behavior, with a particular focus on obesity. In the second part of the review, non-invasive strategies to modulate food-related brain processes and functions will be presented. At the leading edge of non-invasive brain-based technologies is real-time fMRI (rtfMRI) neurofeedback,which isa powerful tooltobetterunderstand thecomplexity ofhuman brain – behavior relation-ships.rtfMRI, aloneor when combinedwith othertechniquesand toolssuch asEEGand cognitivetherapy,could be used to alter neural plasticity and learned behavior to optimize and/or restore healthy cognition and eating behavior. Other promising non-invasive neuromodulation approaches being explored are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS). Converging evidence points at thevalueofthesenon-invasiveneuromodulationstrategiestostudybasicmechanismsunderlyingeatingbehav- iorandtotreatitsdisorders.Bothoftheseapproacheswillbecomparedinlightofrecentworkinthis fi eld,while addressing technical and practical questions. The third part of this review will be dedicated to invasive neuromodulation strategies, such asvagus nerve stimulation (VNS)and deep brain stimulation (DBS).Incombi-nation with neuroimaging approaches, these techniques are promising experimental tools to unravel the intricate relationships between homeostatic and hedonic brain circuits. Their potential as additional therapeutic tools to combat pharmacorefractory morbid obesity or acute eating disorderswillbe discussed, in terms of tech-nicalchallenges, applicability and ethics. In ageneraldiscussion,wewillput the brain at the coreoffundamental research, prevention and therapy in the context of obesity and eating disorders. First, we will discuss the possi-bilityto identifynewbiologicalmarkersofbrainfunctions.Second, wewillhighlightthe potential ofneuroimag- ing and neuromodulation in individualized medicine. Third, we will introduce the ethical questions that are concomitant to the emergence of new neuromodulation therapies. conclusions: the at the core of research, prevention and therapy in the context of obesity and eating intrac-tableobesity,andinducesomeweightlossundermetabolicallyoptimized settings. Two clinical trials on DBS for ANarealsoin progress according to Gorgulho which demonstrate that DBS is a hot topic and promising alternative strategy to combat obesity and eating disorders.