Cortical and limbic activation during viewing of high- versus low-calorie foods

Despite the high prevalence of obesity, eating disorders, and weight-related health problems in modernized cultures, the neural systems regulating human feeding remain poorly understood. Therefore, we applied functional magnetic resonance imaging (fMRI) to study the cerebral responses of 13 healthy normal-weight adult women as they viewed color photographs of food. The motivational salience of the stimuli was manipulated by presenting images from three categories: high-calorie foods, low-calorie foods, and nonedible dining-related utensils. Both food categories were associated with bilateral activation of the amygdala and ventromedial prefrontal cortex. High-calorie foods yielded significant activation within the medial and dorsolateral prefrontal cortex, thalamus, hypothalamus, corpus callosum, and cerebellum. Low-calorie foods yielded smaller regions of focal activation within medial orbitofrontal cortex; primary gustatory/somatosensory cortex; and superior, middle, and medial temporal regions. Findings suggest that the amygdala may be responsive to a general category of biologically relevant stimuli such as food, whereas separate ventromedial prefrontal systems may be activated depending on the perceived reward value or motivational salience of food stimuli.