The Dynamic Nature of the Taste System

Taste perception is a dynamic process influenced by both prior experience and physiological state, as well as by interactions with other sensory modalities. This thesis addresses the dynamic nature of the taste system through three studies that together examine: 1) how experience shapes taste preferences and neural coding, 2) how hormonal fluctuations influence palatability, and 3) how olfactory inputs contribute to taste processing. In the first study, behavioral and electrophysiological methods were used to measure individual preferences between rats and shifts in preferences within the same rat. The results indicated that any taste experience, regardless of the method of delivery, changes the perceptual and neural processing of those tastes. The second study assessed rats’ consumption of tastes across the four stages of the estrous cycle, revealing that there is a general magnification of palatability during metestrus. It was then tested whether this reflects lateral hypothalamic estradiol processing by infusing an estrogen receptor blocker, and found that the effect was blocked during metestrus, delaying until diestrus. Overall, this showed that the estrous cycle directly mediates taste palatability in a manner involving hypothalamic actions of estradiol. The third study, while still underway, began to address the hypothesis that gustatory cortex (GC) and piriform cortex (PC) couple in their responses to tastes and odors by testing the impact of PC inputs on the coding of tastes, odors, and flavors in GC. Together, these findings emphasize the adaptability of the taste system and highlight the integrative mechanisms underlying taste perception.