Linking peripheral taste processes to behavior

Abstract

SUMMARY The act of eating and drinking brings food-related chemicals into contact with taste cells. Activation of these taste cells, in turn, engages neural circuits in the central nervous system that help animals identify foods and fluids, determine what and how much to eat, and prepare the body for digestion and assimilation. Analytically speaking, these neural processes can be divided into at least three categories: stimulus identification, ingestive motivation, and digestive preparation. This review will discuss recent advances in peripheral gustatory mechanisms, primarily from rodent models, in the context of these three major categories of taste function.

High-resolution lesion-mapping strategy links a hot spot in rat insular cortex with impaired expression of taste aversion learning

“…However, whereas the SHAM-LiCl rats maintained strong avoidance of the CS across repeated 46-h Left panels, left of the black vertical line: Mean + SEM intake or preference score for the LiCl-and NaCl-injected rats that met the lesionbased criterion (≥50% bilateral damage to GC: GCX-Li, n = 11; GCX-Na, n = 8) and the sham-operated controls (SHAM-Li, n = 8; SHAM-Na, n = 7) across CTA measures (vertical panels). Although both GCX groups drank slightly more NaCl on the 15-min single-bottle retention test [effect of Lesion: F (1,30) = 5.28, P = 0.03), both GCX-Li and SHAM-Li rats consumed significantly less than did their NaCl-injected counterparts, as indicated by a significant effect of US [F (1,30) Because none of the rats in the SHAM-Li group consumed any sucrose on the 15-min single-bottle test (hence no bar, 0), a series of nonparametric Mann-Whitney U tests were conducted (SHAM-Li versus GCX-Li: U = 60.0, P = 0.19; SHAM-Li versus SHAMNa: U = 0, P ≤ 0.003; GCX-Li versus GCX-Na: U = 0, P ≤ 0.003; Bonferronicorrected). By the final 46-h sucrose two-bottle test, however, the preference for sucrose had increased in the GCX-Li group, but not in the SHAM-Li group [Lesion: F (1,30) = 4.94, P = 0.03; US: F (1,30) = 53.74, P < 0.00001; Lesion × US: F (1,30) = 4.48, P = 0.04].…”

“…Thus, the detailed mapping of the lesion in behaviorally defined subgroups of rats allowed us to exploit the variability in performance to uncloak an important potential component of the functional topography of insular cortex; such an approach could have general applicability to other brain structure-function endeavors as well. W ith its primary receptors situated at the front end of the alimentary tract, the gustatory system is integrally involved in guiding food selection, promoting and discouraging intake, and evoking preparatory physiological reflexes (1). To best serve these functions, taste signals must confer with both the contemporary physiological milieu (e.g., satiety, malaise) and neurally stored representations of the associated effects of that particular taste stimulus [e.g., associative history with visceral malaise, as in conditioned taste aversion (CTA)].…”

Taste receptors in the gastrointestinal system

“…This interaction between single nutrients and taste receptors serves three basic purposes, to identify and discriminate foods and drinks, to promote or discourage ingestion, and to facilitate nutrient utilization by learned anticipatory or cephalic phase responses [2]. In his latest review, Alexander Bachmanov et al describe taste receptors 'as one of the interfaces between internal and external milieus' [1].…”

Receptive field size, chemical and thermal responses, and fiber conduction velocity of rat chorda tympani geniculate ganglion neurons

“…The contrasting taste bud locations suggest different roles in the initial stages of food evaluation. It has been proposed that the role of the anterior tongue in gustatory processing is stimulus identification (Spector and Glendinning 2009), similar to mechanoreceptors on the finger tips (Delmas et al 2011). In fact, it has been known for some time that, like finger mechanoreceptors, single CT afferent fibers terminate in fungiform taste buds that are organized in receptive fields.…”