In contrast, control groups that were each subjected to unpaired presentations of stimuli at the first or second conditioning stage exhibited no significantly increased preference for the CS2, thus indicating that the increased preference for the CS2 in the experimental group is truly the result of second-order conditioning.
Increased preference for ethanol in rats following deprivation.
We found that incentive learning during protracted morphine abstinence drives increased preference for stimuli associated with morphine.
Increased preference for a morphine-paired environment is expressed only when drug-cue conditioning occurs during the abstinent state.
This, in turn, drives increased preference for stimuli associated with morphine during protracted abstinence via incentive learning processes.
However, the addition of trees to the commercial development scenes increased preference ratings substantially.
However, these same morphine-pelleted rats expressed significantly increased preference when they were subsequently re-conditioned for morphine place preference during protracted abstinence.
For example, children have an increased preference for fatty foods if their mothers ate a high-fat diet during pregnancy.
Previous studies from our laboratory found that rats express increased preference for drug-paired stimuli following 2 or 5 weeks of protracted abstinence from chronic drug exposure as compared with naive animals.
One possible explanation for increased drug-induced place preference during abstinence is that the negative affective state of abstinence directly causes increased preference for drug-associated cues, even if the drug-cue associations were formed before dependence.
Results show that drug abstinence alone was not sufficient to drive increased preference for morphine-associated stimuli, but that incentive learning during Pavlovian conditioning in the abstinent state was needed to produce the increased response.
