Cerebral Cortex Advance Access published online on August 14, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp169
How the Brain Represents the Reward Value of Fat in the Mouth
Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK, 1 Current address: Department of Psychology and Helen Wills Neuroscience Institute, University of California at Berkeley, CA 94720-3190, USA, 2 Current address: Psychology Research Group, School of Design, Engineering and Computing, University of Bournemouth, BH12 5BB Bournemouth, UK, 3 Current address: School of Psychology and Trinity College Institute of Neuroscience, Trinity College Dublin 2, Ireland
Address correspondence to Prof Edmund T. Rolls, Oxford Centre for Computational Neuroscience, Oxford, UK and International Digital Laboratory, University of Warwick, CV4 7AL, UK. Email: edmund.Rolls{at}oxcns.org.
The palatability and pleasantness of the sensory properties of foods drive food selection and intake and may contribute to overeating and obesity. Oral fat texture can make food palatable and pleasant. To analyze its neural basis, we correlated humans’ subjective reports of the pleasantness of the texture and flavor of a high- and low-fat food with a vanilla or strawberry flavor, with neural activations measured with functional magnetic resonance imaging. Activity in the midorbitofrontal and anterior cingulate cortex was correlated with the pleasantness of oral fat texture and in nearby locations with the pleasantness of flavor. The pregenual cingulate cortex showed a supralinear response to the combination of high fat and pleasant, sweet flavor, implicating it in the convergence of fat texture and flavor to produce a representation of highly pleasant stimuli. The subjective reports of oral fattiness were correlated with activations in the midorbitofrontal cortex and ventral striatum. The lateral hypothalamus and amygdala were more strongly activated by high- versus low-fat stimuli. This discovery of which brain regions track the subjective hedonic experience of fat texture will help to unravel possible differences in the neural responses in obese versus lean people to oral fat, a driver of food intake.
Key Words: appetite • cingulate cortex • emotion • flavor • insular cortex • orbitofrontal cortex • taste