The word taste commonly evokes the experience of a robust California red wine, a perfectly seasoned and roasted duck breast, or a decadent Belgian chocolate. In fact, the perceptual experience that accompanies ingestion of food is most correctly termed flavor. Flavor comprises combined elements of olfactory (i.e., retronasal odor), somatosensory (e.g., texture and temperature), and gustatory sensations that attend ingestion. In contrast, taste refers exclusively to the perceptions and behaviors that arise when chemical components of food stimulate the gustatory apparatus of the oral cavity, namely taste receptor cells found within taste buds. Consequent neural activity in taste nerves and taste-related areas of the brain lead to gustatory sensation and perception. There is general agreement that activation of the taste system results in the perception of five unique taste qualities, or basic tastes, in humans: sweet, sour, salty, bitter, and umami. It has long been appreciated that perception of these tastes plays a pivotal role in feeding by providing the organism with an appraisal of food nutrient value and/or potential toxicity. Though much remains unknown, our understanding of the gustatory system has burgeoned since 2000. Advances in molecular genetic techniques, for example, provided the launchpad for explosive growth in our understanding of the basic molecular and cellular physiology of taste receptor cells. This information, in turn, has stimulated theoretical, conceptual, and experimental reappraisal of long-standing ideas about the neuroanatomical and neurophysiological bases of taste stimulus coding and perception. Simultaneously, progress in functional brain-imaging technologies permitted non-invasive investigation of the neural pathways and processes involved in taste perception in humans. Results from functional imaging studies have confirmed, extended, and clarified findings from previous psychophysical studies in healthy participants and in patients with peripheral and central nervous system lesions. These studies have also revealed neural correlates of flavor, taste and flavor hedonics, and food-related reward. Combined molecular, behavioral, psychophysical, and imaging data suggest that taste can influence and be influenced by disease. Taste modulates metabolism and contributes to diseases such as obesity, diabetes, and hypertension. Various diseases and the drugs used to treat them can have strong negative impacts on taste, which can lead to impaired nutrition and diminished quality of life. The reciprocal influences of disease and taste signal the importance of considering this sensory modality in health, nutrition, and food industry policies and practice.
Unified neural pathways that gate affective pain and multisensory innate threat signals to the amygdala
