Abstract
The sensation of taste has both cognitive and hedonic aspects of reward and aversion. Recognition of quality and quantity of food is necessary to compare it to the previous experiences and to remember it for future identification. Hedonic evaluation, on the other hand, plays a critical role in the decision of acceptance or rejection of the food. For example, the sweet taste of sugar is innately associated with palatability, or positive hedonics, and its ingestion is facilitated. However, if the ingestion of sugar is followed by illness, the hedonic value of the sugar changes from positive to negative and its ingestion is rejected even if its sweetness is essentially the same. Taste information is conveyed through the central gustatory pathways to the cortical gustatory area and is processed in terms of qualitative and quantitative aspects. Taste information is also sent to the reward system and feeding center via several brain sites including the prefrontal cortex, insular cortex and amygdala. The reward system contains the ventral tegmental area, nucleus accumbens and ventral pallidum and finally sends information to the lateral hypothalamic area, the feeding center. The dopamine system originating from the ventral tegmental area mediates the motivation to consume palatable food. The actual ingestive behavior is promoted by the orexigenic neuropeptides from the hypothalamus. Finally, the neural substrate of learning and memory of taste is introduced and the biological significance will be discussed in terms of survival of life. [J Physiol Sci. 2007;57 Suppl:S40]
