From Channels to Behavior An Integrative Model of NaCl Taste

or transducin), in turn, causes an increase in phosphodi-esterase activity, resulting in decreased levels of cAMP, ultimately leading to an increase in Ca 2ϩ influx. In addi-for sugars involves the G protein–mediated activation of adenylyl cyclase and the production of cAMP, whereas Baton Rouge, Louisiana 70808 saccharin, an artificial sweetener, activates phospholi-pase C, causing the production of IP 3 (Cummings et al., 1996). Either pathway ultimately results in a block of An issue common to sensory research is how to reconcile transduction mechanisms, elucidated by molecular voltage-gated K ϩ channels in TRCs leading to depolar-ization, but this does not necessarily imply the existence and physiological studies, with perception. In gustatory research, stimuli and their transduction mechanisms are of multiple sweet taste mechanisms within a single cell. Other receptor-mediated events have been implicated often characterized in terms of human perceptual expe-riences—e.g., a mechanism for citric acid–evoked depo-in the transduction of taste stimuli in mammals. The receptor for glutamate taste (" umami ") may be a metab-larization of a taste receptor cell may be described as a mechanism for sour taste. Because transduction is otropic glutamate receptor that has been cloned from rat taste cells (Chaudhari et al., 1996). Additionally, recent studied in a variety of species, and because the mechanisms for common stimuli tend to vary across species, studies in rat indicate the existence of a taste transduc-tion mechanism for dietary fat: essential fatty acids, this association between transduction events at the receptor level with human perception is problematic. It is generated by the actions of lingual lipase on fats, directly therefore important to try to relate transduction mechanisms to both neural organization and behavioral abilities of the model species. Indeed, recent studies in mammalian gustation have used a variety of techniques to construct models that link receptor mechanisms with behavioral responses. Perhaps the most complete model involves the role that the amiloride-sensitive sodium channels (ASSCs) in mammalian taste receptor cells play in determining how an animal discriminates among salt stimuli. General Mechanisms of Taste Transduction Taste transduction, in mammals, occurs in taste buds located in several distinct regions on the tongue, palate, and other areas of the oral cavity. Sapid stimuli interact with receptors or ion channels on the apical membranes of taste receptor cells (TRCs), producing a depolariza-tion, or receptor potential, within the cell. The receptor potential ultimately results in a rise in intracellular Ca 2ϩ that triggers transmitter …