Relation of consummatory responses and preabsorptive insulin release to palatability and learned taste aversions.

The oral stimulation arising from food in the mouth produces a stereotyped sequence of ingestive consummatory responses in rats and a rapid release of insulin prior to the absorption of nutrients into the blood. Conversely, when noxious taste stimuli are infused into the mouth, a different, aversive set of consummatory responses is evoked, and no insulin is released. These experiments demonstrate that pairing a sapid taste solution with LiCl suffices to reverse the consummatory response sequence to subsequent presentations of that taste from ingestion to aversion and to abolish the preabsorptive release of insulin to that taste. This indicates an experience-produced shift in the palatability of the taste. It was further shown that a palatable but categorically noncaloric taste elicits behavioral ingestion but no insulin release, and it is concluded that separate but related control systems operate to produce consummatory behavior and ingestive neuroendocrine responses.