Imaging methodologies and applications for nutrition research: what can functional MRI offer?

Abstract

Food intake is influenced by a complex regulatory system involving the integration of a wide variety of sensory inputs across multiple brain areas. Over the past decade, advances in neuroimaging using functional MRI (f MRI) have provided valuable insight into these pathways in the human brain. This review provides an outline of the methodology of f MRI, introducing the widely used blood oxygenation level-dependent contrast for f MRI and direct measures of cerebral blood flow using arterial spin labelling. A review of f MRI studies of the brain's response to taste, aroma and oral somatosensation, and how fat is sensed and mapped in the brain in relation to the pleasantness of food, and appetite control is given. The influence of phenotype on individual variability in cortical responses is addressed, and an overview of f MRI studies investigating hormonal influences (e.g. peptide YY, cholecystokinin and ghrelin) on appetiterelated brain processes provided. Finally, recent developments in MR technology at ultrahigh field (7 T) are introduced, highlighting the advances this can provide for f MRI studies to investigate the neural underpinnings in nutrition research. In conclusion, neuroimaging methods provide valuable insight into the mechanisms of flavour perception and appetite behaviour. Over the past decade, advances in neuroimaging techniques, particularly functional MRI (f MRI), have provided valuable insight into central food-related pathways in the human brain. This review outlines recent advances in f MRI to understand flavour perception and human appetitive behaviour. A brief overview of the method of f MRI and the blood oxygenation level-dependent (BOLD) contrast generally used in f MRI is provided, together with how more direct measures of cerebral blood flow (CBF) can be assessed. f MRI studies of the brain's response to taste, aroma and flavour perception are outlined. The question of how fat is sensed and mapped in the brain in relation to the pleasantness of food, appetite control and hormonal influences is addressed. The role of neuroimaging studies to assess eating behaviour in obesity will be outlined. Finally, recent developments in MR technology, and the advances they can provide for future f MRI studies to investigate the neural underpinnings in nutrition research will be described. Principles of functional MRIf MRI has revolutionised the research of functional brain mapping and is now the most widely used method for mapping brain activity. f MRI measures brain activity *Corresponding author: Dr S. Francis, email susan.francis@nottingham.ac.uk ‡ The original version of this article was published with incorrect conference details. A notice detailing this has been published and the error rectified in the online and print PDF and HTML copies.

Impaired Brain Satiety Responses After Weight Loss in Children With Obesity

“…In a previous fMRI study in fasted lean adults, De Silva et al demonstrated that the combined administration of PYY and GLP-1 attenuated brain areas that are involved in appetitive behavior, including amygdala, caudate, insula, nucleus accumbens, OFC, and putamen, thereby supporting that pharmacologic provision of these hormones ( 48 , 49 ), affects activation within brain areas included in our study. In another fMRI study following a test meal, ghrelin levels were associated with activation in the insula, amygdala, and OFC, while GLP-1 was associated with reduced activation in insula and OFC ( 50 ), demonstrating a potential relation between meal-induced changes of gut hormones and changes in brain areas involved in appetitive behavior.…”

Food, Eating, and the Gastrointestinal Tract

“…These sensory experiences are associated with pleasant or occasionally unpleasant sensations (changes in mood and digestive well-being), i.e., the hedonic dimension of the sensory experience [12][13][14]18,19]. Changes in the activity of the central nervous system (CNS) in response to meal ingestion have been documented by means of functional brain imaging (e.g., functional magnetic resonance imaging and positron emission tomography) [20][21][22][23][24][25][26]. These studies reveal the crucial role of the CNS in the control of food intake and the conscious perception of sensation and in the maintenance of homeostasis [27].…”

Biogastronomy: Factors that determine the biological response to meal ingestion

“…[43][44][45][46] In humans, changes in brain activity can be detected by different methods, such as functional magnetic resonance imaging and positron emission tomography. [47][48][49] The central nervous system plays a key role in homeostasis, control of food intake and perception of conscious sensations. 50…”