NUTRIENT-CONDITIONED FLAVOR PREFERENCE AND ACCEPTANCE IN RATS - EFFECTS OF DEPRIVATION STATE AND NONREINFORCEMENT

Rats acquire strong preferences for flavors paired with intragastric ( IG) Polycose infusions. The present study investigated the ingestive r esponses to these flavors when they were no longer reinforced. All rat s were first trained to associate a CS+ flavor with IG 32% Polycose an d a CS- flavor with IG water during 23 h/day sessions. Experiment. 1 e xamined the effects of deprivation on short-term (4 h/day) CS intakes under nonreinforcement conditions. Food deprivation selectively enhanc ed CS+ intake whereas water deprivation increased both CS+ and CS- int akes. The results also suggested that extinction training differential ly affects CS+ preference and acceptance as measured by relative and a bsolute intakes. This was confirmed in a second experiment. The rats' absolute intake of the CS+ solution during 4 h/day sessions significan tly decreased when it was no longer paired with IG Polycose infusions; yet the rats continued to show a strong preference for the CS+ over t he CS- in both 4 h and 23 h/day tests. Experiment 3 examined the effec ts of extensive long-term extinction training on the CS+ preference. W hen the alternative was plain water, the CS+ preference extinguished o ver 12 days. Yet the same rats continued to prefer the CS+ to the CS- during 12 additional extinction days and during 16 extinction days tha t followed a 1-month rest period. The CS+ preference relative to the C S- was blocked only when the CS+ was paired with food deprivation and the CS- was paired with food repletion. These experiments confirm earl ier reports of the resistance of Polycose-conditioned flavor preferenc es to extinction but also show that flavor acceptance is more suscepti ble to extinction. Flavor acceptance was not completely extinguished, however, and remained responsive to deprivation state.