Learning through the taste system

Abstract

Taste is the final arbiter of which chemicals from the environment will be admitted to the body. The action of swallowing a substance leads to a physiological consequence of which the taste system should be informed. Accordingly, taste neurons in the central nervous system are closely allied with those that receive input from the viscera so as to monitor the impact of a recently ingested substance. There is behavioral, anatomical, electrophysiological, gene expression, and neurochemical evidence that the consequences of ingestion influence subsequent food selection through development of either a conditioned taste aversion (CTA) (if illness ensues) or a conditioned taste preference (CTP) (if nutrition). This ongoing communication between taste and the viscera permits the animal to tailor its taste system to its individual needs over a lifetime.

Keywords: conditioned taste aversion; conditioned taste preference; learning; rat; taste.

Figure 1

Post-stimulus time histograms of the mean responses among sweet-sensitive neurons in the nucleus of the solitary tract to the conditioned stimulus: 0.0025 M sodium saccharin. Activity is shown for control (dotted line), pseudoconditioned (dashed line), and conditioned (solid line) rats. The enhanced activity during the first three seconds of the evoked response in conditioned animals may represent the increased salience of the sodium saccharin taste and its aversive quality.