Age differences and the interstimulus interval context in long-delay taste-aversion conditioning of rats.

Young-adult and old-adult rats were allowed to remain in the conditioning context or were returned to their home cages during a 3-hr. interval to assess whether previously observed age differences in long-delay taste-aversion conditioning may be due to age differences in the use of home-cage cues to mediate the CS-US association over a long delay. The old adults but not the young adults showed an aversion irrespective of the context in which they were detained during the interstimulus interval. These results suggest that young-adult rats do not use the interstimulus context cues to mediate the association over a delay interval. They suggest, rather, that context cues, which are more contiguous with the US than taste cues in long-delay conditioning, may be more effective in overshadowing taste cues in young adults than in old adults.