CENTRAL OR PERIPHERAL MEDIATION OF LEARNING WITH LONG CS-US INTERVALS IN FEEDING SYSTEM

Rats can be trained to avoid a particular solution when ingestion of this solution is followed after 30 min. by injection of apomorphine, a drug that seems to produce aversive gastrointestinal consequences. Aversions with long CS-UCS intervals can be established much more easily with taste as a CS than any other cues. This suggests that aftertastes may provide peripheral mediation of the long-delay interval. In a series of experiments, it was shown that rats can learn to avoid 1 of 2 concentrations of the same substance when ingestion of 1 concentration either higher or lower is followed by apomorphine injection after 30 min. Such learning seems incompatible with an aftertaste interpretation, and suggests that the long-delay learning is centrally mediated. The experiments suggest that apomorphine based aversions to stimuli outside the taste modality may be established if there is a close CS-UCS contingency, and no distinctive gustatory stimuli are present. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.