Gaining new insights into food reward with functional neuroimaging.

The notion that eating is intimately related to feelings of pleasure is not new. Indeed, in an environment characterised by many varied and palatable foods, hedonistic drives are likely to play a greater role in modulating food intake than homeostatic ones. Until recently however, a neurobiological account of the rewarding properties of food was lacking. The ability to reveal functional brain activity has been made possible with the advent of functional neuroimaging techniques such as electroencephalography (EEG), magnetoencephalography (MEG), positron emission tomography (PET) and most recently, functional magnetic resonance imaging (fMRI). Neuroimaging studies in fed and fasted, lean and obese, normal and pathological states have revealed variations in food-related reward processing. Eating is a multi-sensory experience and understanding the precise mechanisms by which food modulates reward circuits will be important in understanding the aetiology of obesity and eating disorders. Here we review the development of functional neuroimaging as a research tool and recent neuroimaging studies relating to food reward. In particular, we evaluate the ability of leptin and the gut hormones peptide YY3-36 and ghrelin to modulate activity in reward-related brain regions. Finally, we discuss the potential to use such information to guide development of pharmaceuticals, functional foods and life-style modifications.