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

https://doi.org/10.1016/j.nicl.2015.03.016Get rights and content
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Highlights

  • We review the neural vulnerability factors related to obesity and eating disorders.

  • We compare the pros and cons of neuroimaging techniques to study eating behavior.

  • We present non-invasive strategies to modulate food-related brain processes.

  • We also present invasive neuromodulation methods such as VNS and DBS.

  • We discuss about neuroimaging and neuromodulation for prevention and therapy.

Abstract

Functional, molecular and genetic neuroimaging has highlighted the existence of brain anomalies and neural vulnerability factors related to obesity and eating disorders such as binge eating or anorexia nervosa. In particular, decreased basal metabolism in the prefrontal cortex and striatum as well as dopaminergic alterations have been described in obese subjects, in parallel with increased activation of reward brain areas in response to palatable food cues. Elevated reward region responsivity may trigger food craving and predict future weight gain. This opens the way to prevention studies using functional and molecular neuroimaging to perform early diagnostics and to phenotype subjects at risk by exploring different neurobehavioral dimensions of the food choices and motivation processes. In the first part of this review, advantages and limitations of neuroimaging techniques, such as 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 is a powerful tool to better understand the complexity of human brain–behavior relationships. rtfMRI, alone or when combined with other techniques and tools such as EEG and cognitive therapy, 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 the value of these non-invasive neuromodulation strategies to study basic mechanisms underlying eating behavior and to treat its disorders. Both of these approaches will be compared in light of recent work in this field, while addressing technical and practical questions. The third part of this review will be dedicated to invasive neuromodulation strategies, such as vagus nerve stimulation (VNS) and deep brain stimulation (DBS). In combination 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 disorders will be discussed, in terms of technical challenges, applicability and ethics. In a general discussion, we will put the brain at the core of fundamental research, prevention and therapy in the context of obesity and eating disorders. First, we will discuss the possibility to identify new biological markers of brain functions. Second, we will highlight the potential of neuroimaging and neuromodulation in individualized medicine. Third, we will introduce the ethical questions that are concomitant to the emergence of new neuromodulation therapies.

Abbreviations

5-HT
serotonin
aCC
anterior cingulate cortex
ADHD
attention deficit hyperactivity disorder
AN
anorexia nervosa
ANT
anterior nucleus of the thalamus
BAT
brown adipose tissue
BED
binge eating disorder
BMI
body mass index
B N
bulimia nervosa
BOLD
blood oxygenation level dependent
BS
bariatric surgery
CBF
cerebral blood flow
CCK
cholecystokinin
Cg25
subgenual cingulate cortex
DA
dopamine
daCC
dorsal anterior cingulate cortex
DAT
dopamine transporter
DBS
deep brain stimulation
DBT
deep brain therapy
dlPFC
dorsolateral prefrontal cortex
DTI
diffusion tensor imaging
dTMS
deep transcranial magnetic stimulation
ED
eating disorders
EEG
electroencephalography
fMRI
functional magnetic resonance imaging
fNIRS
functional near-infrared spectroscopy
GP
globus pallidus
HD-tDCS
high-definition transcranial direct current stimulation
HFD
high-fat diet
HHb
deoxygenated-hemoglobin
LHA
lateral hypothalamus
lPFC
lateral prefrontal cortex
MER
microelectrode recording
MRS
magnetic resonance spectroscopy
Nac
nucleus accumbens
OCD
obsessive–compulsive disorder
OFC
orbitofrontal cortex
O2Hb
oxygenated-hemoglobin
pCC
posterior cingulate cortex
PD
Parkinson's disease
PET
positron emission tomography
PFC
prefrontal cortex
PYY
peptide tyrosine tyrosine
rCBF
regional cerebral blood flow
rtfMRI
real-time functional magnetic resonance imaging
rTMS
repetitive transcranial magnetic stimulation
SPECT
single photon emission computed tomography
STN
subthalamic nucleus
tACS
transcranial alternate current stimulation
tDCS
transcranial direct current stimulation
TMS
transcranial magnetic stimulation
TRD
treatment-resistant depression
tRNS
transcranial random noise stimulation
VBM
voxel-based morphometry
vlPFC
ventrolateral prefrontal cortex
vmH
ventromedial hypothalamus
vmPFC
ventromedial prefrontal cortex
VN
vagus nerve
VNS
vagus nerve stimulation
VS
ventral striatum
VTA
ventral tegmental area

Keywords

Brain
Neuroimaging
Neuromodulation
Obesity
Eating disorders
Human

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