The human orbitofrontal cortex (OFC) plays an important role in representing taste, flavor, and food reward. The primary role of the OFC in taste is thought to be the encoding of affective value and the computation of perceived pleasantness. The OFC also encodes retronasal olfaction and oral somatosensation. During eating, distinct sensory inputs fuse into a unitary flavor percept, and there is evidence that this percept is encoded in the orbital cortex. Studies examining the effect of internal state on neural representation of food and drink further suggest that processing in the OFC is critical for representing the reward value of foods. Thus, it is likely that, in addition to serving as higher-order gustatory cortex, the OFC integrates multiple sensory inputs and computes reward value to guide feeding behavior.

Controversy exists over whether exposure to artificial sweeteners degrades the predictive relationship between sweet taste and its post-ingestive consequences. Here we tested whether brain response to caloric sucrose is influenced by individual differences in self-reported artificial sweetener use. Twenty-six subjects participated in fMRI scanning while consuming sucrose solutions. A negative correlation between artificial sweetener use and amygdala response to sucrose ingestion was observed. This finding supports the hypothesis that artificial sweetener use may be associated with brain changes that could influence eating behavior.

Taste, which is almost always accompanied by other oral sensations, serves to identify potential nutrients and toxins. The present study was designed to determine the influence of sensory modality (chemesthetic vs. gustatory) and physiological significance (potentially nutritive vs. potentially harmful) on insular response to oral stimulation. Sixteen subjects underwent functional magnetic resonance imaging scanning while receiving 2 potentially nutritive solutions (sucrose and NaCl), 2 potentially harmful solutions (quinine and capsaicin, a chemesthetic stimulus), and a tasteless control solution. We identified a region of anterior ventral insula that responded to oral stimulation irrespective of modality or physiological significance. However, when subjects tasted a potentially nutritive stimulus, the connectivity between the insula and a feeding network including the hypothalamus, ventral pallidum, and striatum was greater than when tasting a potentially harmful stimulus. No differential connectivity was observed as a function of modality (gustatory vs. chemesthetic). These results support the existence of an integrated supramodal flavor system in the anterior ventral insula that preferentially communicates with the circuits guiding feeding when the flavor is potentially nutritive.