| The taste system serves a variety of related but distinct functions. Reflexes include salivation and other cephalic phase responses like insulin release. Taste stimuli also reflexively modulate oral movements and facial expressions (you can easily discern if a person has just bitten into something they find distasteful!). Taste reflexes are mediated by brainstem circuits. Gustatory signals also potently affect motivation-- consider the effect of a tantalizing desert on your desire to eat. The areas of the brain that mediate motivational taste effects include ventral forebrain regions like the hypothalamus and amygdala. Taste also serves a discriminative role and taste processing is impacted by prior experience. Discrimination and learning occur mainly in cortex. The NST is a complex circuit that provides input for all these functions. Current studies utilize anatomical tracing, in situ hybridization, and immunochemistry to unravel the pathways and chemicals messengers by which this is accomplished. | |
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Coronal NST sections immunostained for the enzyme nitric oxide synthase (NOS), that synthesizes the gaseous neurotransmitter, nitric oxide (NO), and the retrograde tracer, Flurorogold (FG). The section on the left is from an animal in which a FG injection was made into the medullary reticular formation, to retrogradely label neurons giving rise to reflex pathways. The section on the right is from an animal with an injection in the parabrachial nucleus (PBN). The PBN projects to the forebrain and so retrogradely-stained neurons in this section potentially contribute to higher-level functions. Some NST neurons involved in both types of appear to utilize NO. |
| Relevant
Publications Halsell, C.B., Travers, S.P., and Travers, J.B. Ascending and descending projections from the rostral nucleus of the solitary tract originate from separate neuronal populations. Neuroscience 72: 185-197, 1996. Travers, S.P. and Hu, H. Extranuclear projections of rNST neurons expressing gustatory-elicited Fos. Journal of Comparative Neurology, 427: 124-138, 2000. Travers, S.P. Co-localization of gustatory-elicited Fos-like immunoreactivity and NADPH in the NST and medullary reticular formation. Society for Neuroscience Abstracts 26. 1972, 2000. Travers, S.P. and Shiroor, C.. Projections of NST nitrergic neurons. Assocation for Chemoreception Sciences Abstracts, 2003. <Homepage |
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