Consummatory induction through post-ingestive consequences but not through an S-S association between subsequent foods.

FREIDIN, E.; CATANESE, F.; CUELLO, M.I.; DISTEL, R.A.

Huerta Grande, Córdoba

Congreso; I Reunión Conjunta de Neurociencias; 2009

Sociedad Argentina de Investigación en Neurociencias

The sequential presentation of two foodstuffs may increase the consumption of the first when the following meal is of higher hedonic value (i.e., an induction effect). It is commonly assumed that this induction is based on a stimulus-stimulus (S-S) learned association between subsequent incentives. We describe two experiments where we found an induction effect in sheep and tested its putative mechanism. In experiment 1, sheep consumed a food with high fiber content (oat hay: OH) followed by either an empty feeder (control 1), more OH (control 2), a food rich in protein (group P), or a food rich in carbohydrates (group C). Groups P and C ate more OH than both controls, thus showing an induction effect. In experiment 2, we used two flavors associated with OH in a within-subject design where one flavor was always followed by a food rich in protein and the other always followed by an empty feeder. In a choice test, sheep showed a strong preference for the flavor followed by protein. Afterwards, we induced gastric sickness in all animals administering LiCl after they had access to either the protein food (for half the subjects) or a non-experimental already familiar food (for the other half of subjects). If sheep’s flavor preference depended on an S-S association, we expected to revert the original preference in the group intoxicated after protein consumption but not in the other group. Despite developing an aversion to the corresponding food, flavor preferences remained unaltered in both groups. This suggests that the induction effect and flavor preference were determined by postingestive consequences of the protein-rich food but not by an S-S association between flavor and the subsequent foodstuff.