Odor Coding in the Brain
When a food is eaten to satiety, the pleasantness of its smell and taste are reduced. The important consequence of this effect, referred to as “sensory-specific satiety,” is to diminish consumption of the sated food, and to promote food search for different items containing other nutritional benefits. Presently, the neural mechanisms regulating appetite states in a sensory-specific manner are poorly understood. In addition, because most odors naturally encountered in the environment are complex assortments of dozens, or even hundreds, of different odorous molecules, it is not known whether sensory-specific satiety modulates the rewarding value of a pleasant food smell at the level of the whole odor, or for specific odor components carrying particular behavioral salience. The research proposed here combines highresolution functional MRI and analytical chemistry techniques with an olfactory satiety paradigm to elucidate how information about food reward value is modulated in the human brain. Findings from the proposed work may have a far-reaching impact on the basic and clinical science of eating disorders and obesity, given that a relative neural insensitivity, or derangement, to hunger and satiety signals may contribute to dietary imbalances and appetite dysregulation.