Aging facilitates long-trace taste-aversion conditioning in rats.

In order to examine age-related changes in long-trace conditioning, five age groups (0.25, 1, 1.5, 2, and 2.5 years) of Wistar-derived female albino rats were subjected to taste-aversion conditioning at one of five conditioned stimulus-conditioned stimulus (CS-US) intervals (0, 45, 90, 180, and 360 min). Age differences in the strength of the aversion were evident at CS-US intervals greater than 0 min and the strength of the aversion was directly related to age. An aversion was conditioned in only the two oldest age groups when the CS-US interval was 360 min. The age differences in taste-aversion and the superior long-trace conditioning in old-age rats were attributed to factors that accompany aging, for example, the gradual slowing down of a metabolic pacemaker.