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Obesity; Neuroimaging; Functional magnetic resonance tomography; voxel-based morphometry; positron emission tomography
Abstract:
Neuroimaging Technologies in
Obesity Research.
Neurological correlates
of obesity have been extensively discussed
and investigated over the last few years. Use
of neuroima ging technology provides novel ap-
proaches to obesity research. Among these,
magnetic resonance imaging (MRI) and positron
emission tomography (PET) appear to be most
promising. Due to the great variability of con-
founding factors on brain development many
selection criteria have to be fulfi lled in order to
assure the reliability of a neuroimaging study.
The number of highly capable MRI and PET in-
vestigation centers is increasing, especially in
large urban areas where highly characterized
cohorts of subjects can be recruited. Recent in-
vestigations have shown that the human brain
receives and distributes homeostatic and he-
donic impulses to regulate eating behavior. Both
hunger and appetite are distinct aspects of the
drive to eat originating in different brain areas,
yet subject to a common regulating center. The
responsible areas appear to be structurally and
functionally altered in obesity, including chang-
es in the reward system. Women and men (both
lean and obese) seem to respond differentially
to homeostatic and hedonic stimuli for hunger
and satiety. The “hun ger networks” are affect-
ed by genetic, biochemical, hormonal, neuronal,
and other factors. For example ghrelin, peptide
YY, and leptin are claimed to be endocrine sig-
nals from the gastro intes ti nal tract and adipose
tissue not only regulating metabolic activity and
nutrient distribution but also possessing central
nervous effects. These hormones act as short-
time or long-time modulators of specifi c brain
areas with homeostatic or hedonic power on
food evaluation and eating behavior. Know-
ing the interactions of certain brain regions in
the regulation of hunger/appetite and satiety/
satiation will allow for the development of new
therapeutic agents against obesity.
