Thalamic taste responses to changing stimulus concentration

Abstract

In the rat brainstem, where responses are often vigorous to basic gustatory stimuli, the code for taste intensity appears to be a function of total neural activity. By contrast, thalamic neurons respond sluggishly to stimuli representing the four basic taste qualities, and total neural activity does not rise significantly with increasing stimulus concentration. Rather, most thalamic cells (61%) show sensitivity to concentration changes of one or more qualities, but a distinct minority are unaffected by intensity. Further, increases in stimulus concentration may affect the neurons which are sensitive either directly or inversely. Thus, only a subpopulation of thalamic neurons seems to signal stimulus intensity, doing so through both excitatory and inhibitory responses. The role of the thalamus in processing taste information is discussed.