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The use of functional MRI to study appetite control in the CNS.

De Silva A, Salem V, Matthews PM, Dhillo WS - Exp Diabetes Res (2012)

Bottom Line: In the present absence of any safe or effective centrally acting appetite suppressants, a better understanding of how appetite is controlled is vital for the development of new antiobesity pharmacotherapies.Early functional imaging techniques revealed an attenuation of brain reward area activity in response to visual food stimuli when humans are fed-in other words, the physiological state of hunger somehow increases the appeal value of food.The hypothalamus acts as a central gateway modulating homeostatic and nonhomeostatic drives to eat.

View Article: PubMed Central - PubMed

Affiliation: Division of Diabetes, Endocrinology and Metabolism, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.

ABSTRACT
Functional magnetic resonance imaging (fMRI) has provided the opportunity to safely investigate the workings of the human brain. This paper focuses on its use in the field of human appetitive behaviour and its impact in obesity research. In the present absence of any safe or effective centrally acting appetite suppressants, a better understanding of how appetite is controlled is vital for the development of new antiobesity pharmacotherapies. Early functional imaging techniques revealed an attenuation of brain reward area activity in response to visual food stimuli when humans are fed-in other words, the physiological state of hunger somehow increases the appeal value of food. Later studies have investigated the action of appetite modulating hormones on the fMRI signal, showing how the attenuation of brain reward region activity that follows feeding can be recreated in the fasted state by the administration of anorectic gut hormones. Furthermore, differences in brain activity between obese and lean individuals have provided clues about the possible aetiology of overeating. The hypothalamus acts as a central gateway modulating homeostatic and nonhomeostatic drives to eat. As fMRI techniques constantly improve, functional data regarding the role of this small but hugely important structure in appetite control is emerging.

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Related in: MedlinePlus

Modulation of neuronal activity in the fed versus fasted state. Representative whole-brain fMRI sections showing regions where the difference in BOLD signal between viewing food images and nonfood images is blunted in the fed state compared with the fasted state. Unpublished image from [37].
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fig3: Modulation of neuronal activity in the fed versus fasted state. Representative whole-brain fMRI sections showing regions where the difference in BOLD signal between viewing food images and nonfood images is blunted in the fed state compared with the fasted state. Unpublished image from [37].

Mentions: In 2006, Porubská et al. published the results of an fMRI study of 12 normal-weight fasted subjects. Visual food stimuli (in contrast to nonfood images) activated the insular and orbitofrontal cortices, with a positive modulation of insular activity induced by subjective ratings of appetite [34]. These findings are consistent with the recognition of the insula as being an important region in establishing salience [35]. Following on from this, Führer et al. in 2008 studied 12 healthy male volunteers undergoing two separate scanning sessions—one when fasted overnight and the other immediately after a large meal. They performed a whole brain, uncorrected analysis of the data and particularly noted significantly enhanced activity within the OFC when hungry, again with reference to our understanding of this area as subjectifying the perceived pleasantness of food [36]. We have also recently demonstrated that feeding reduces the difference in BOLD signal between viewing images of food and nonfood in several brain regions (Figure 3), but significantly so in the insula [37]. Furthermore, in 2009, Goldstone et al. reported the findings from a fMRI study of twenty individuals in both the fed and fasted state; subjects viewed pictures of high calorie, low calorie, and nonfood items whilst rating the appeal value of these images. They found that when fasted, there was significantly greater activation to high calorie over low calorie food items in the ventral striatum (important in mediating hedonic drive and action [38]), amygdala, anterior insula, and OFC. They found that high calorie foods were consistently rated as more appealing, that this was augmented with fasting and that the increase in appeal rating bias for high calorie over low calorie foods in the fasted state was positively correlated with activity in the OFC [39]. In the same year, Schur et al. performed a study of ten normal weight, fed subjects viewing images of fattening food, nonfattening food, and nonfood items. These food images were specifically chosen based on whether the food was perceived to be compatible with an effort to lose weight. In a ROI analysis, this was the first study to report increased hypothalamic activation when viewing pictures of fattening food compared with nonfood items, although this finding did not extend to other comparisons (i.e., fattening versus nonfattening or all food versus nonfood). In concordance with other studies, they also found increased activation in the amygdala, insula and OFC when viewing fattening foods compared with nonfood items [40]. Also in agreement with previous findings were the results of Siep et al., who in 2009 reported increased activity in the amygdala and OFC in response to viewing high calorie versus low calorie food images, but only when their subjects were fasted [41]. Their experimental protocol allowed for the further observation that this increased activity in the amygdala and OFC was only evident when participants explicitly evaluated foods but not when their concentration was diverted elsewhere.


The use of functional MRI to study appetite control in the CNS.

De Silva A, Salem V, Matthews PM, Dhillo WS - Exp Diabetes Res (2012)

Modulation of neuronal activity in the fed versus fasted state. Representative whole-brain fMRI sections showing regions where the difference in BOLD signal between viewing food images and nonfood images is blunted in the fed state compared with the fasted state. Unpublished image from [37].
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376546&req=5

fig3: Modulation of neuronal activity in the fed versus fasted state. Representative whole-brain fMRI sections showing regions where the difference in BOLD signal between viewing food images and nonfood images is blunted in the fed state compared with the fasted state. Unpublished image from [37].
Mentions: In 2006, Porubská et al. published the results of an fMRI study of 12 normal-weight fasted subjects. Visual food stimuli (in contrast to nonfood images) activated the insular and orbitofrontal cortices, with a positive modulation of insular activity induced by subjective ratings of appetite [34]. These findings are consistent with the recognition of the insula as being an important region in establishing salience [35]. Following on from this, Führer et al. in 2008 studied 12 healthy male volunteers undergoing two separate scanning sessions—one when fasted overnight and the other immediately after a large meal. They performed a whole brain, uncorrected analysis of the data and particularly noted significantly enhanced activity within the OFC when hungry, again with reference to our understanding of this area as subjectifying the perceived pleasantness of food [36]. We have also recently demonstrated that feeding reduces the difference in BOLD signal between viewing images of food and nonfood in several brain regions (Figure 3), but significantly so in the insula [37]. Furthermore, in 2009, Goldstone et al. reported the findings from a fMRI study of twenty individuals in both the fed and fasted state; subjects viewed pictures of high calorie, low calorie, and nonfood items whilst rating the appeal value of these images. They found that when fasted, there was significantly greater activation to high calorie over low calorie food items in the ventral striatum (important in mediating hedonic drive and action [38]), amygdala, anterior insula, and OFC. They found that high calorie foods were consistently rated as more appealing, that this was augmented with fasting and that the increase in appeal rating bias for high calorie over low calorie foods in the fasted state was positively correlated with activity in the OFC [39]. In the same year, Schur et al. performed a study of ten normal weight, fed subjects viewing images of fattening food, nonfattening food, and nonfood items. These food images were specifically chosen based on whether the food was perceived to be compatible with an effort to lose weight. In a ROI analysis, this was the first study to report increased hypothalamic activation when viewing pictures of fattening food compared with nonfood items, although this finding did not extend to other comparisons (i.e., fattening versus nonfattening or all food versus nonfood). In concordance with other studies, they also found increased activation in the amygdala, insula and OFC when viewing fattening foods compared with nonfood items [40]. Also in agreement with previous findings were the results of Siep et al., who in 2009 reported increased activity in the amygdala and OFC in response to viewing high calorie versus low calorie food images, but only when their subjects were fasted [41]. Their experimental protocol allowed for the further observation that this increased activity in the amygdala and OFC was only evident when participants explicitly evaluated foods but not when their concentration was diverted elsewhere.

Bottom Line: In the present absence of any safe or effective centrally acting appetite suppressants, a better understanding of how appetite is controlled is vital for the development of new antiobesity pharmacotherapies.Early functional imaging techniques revealed an attenuation of brain reward area activity in response to visual food stimuli when humans are fed-in other words, the physiological state of hunger somehow increases the appeal value of food.The hypothalamus acts as a central gateway modulating homeostatic and nonhomeostatic drives to eat.

View Article: PubMed Central - PubMed

Affiliation: Division of Diabetes, Endocrinology and Metabolism, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.

ABSTRACT
Functional magnetic resonance imaging (fMRI) has provided the opportunity to safely investigate the workings of the human brain. This paper focuses on its use in the field of human appetitive behaviour and its impact in obesity research. In the present absence of any safe or effective centrally acting appetite suppressants, a better understanding of how appetite is controlled is vital for the development of new antiobesity pharmacotherapies. Early functional imaging techniques revealed an attenuation of brain reward area activity in response to visual food stimuli when humans are fed-in other words, the physiological state of hunger somehow increases the appeal value of food. Later studies have investigated the action of appetite modulating hormones on the fMRI signal, showing how the attenuation of brain reward region activity that follows feeding can be recreated in the fasted state by the administration of anorectic gut hormones. Furthermore, differences in brain activity between obese and lean individuals have provided clues about the possible aetiology of overeating. The hypothalamus acts as a central gateway modulating homeostatic and nonhomeostatic drives to eat. As fMRI techniques constantly improve, functional data regarding the role of this small but hugely important structure in appetite control is emerging.

Show MeSH
Related in: MedlinePlus