Retention of conditioned taste aversion in weanling, adult, and old-age rats

Rats ranging in age from weanling to old age were given a single saccharin/lithium chloride pairing and were tested for saccharin aversion 1 or 28 days later. Weanling, adult, and old-age rats did not differ in their retention of the conditioned aversion at the 1-day retention interval, but weanling rats showed substantially less aversion than adult and old-age rats at the 28-day interval. The old-age rats did not differ from the adults at either retention interval. As old-age rats generally forget a passive avoidance task sooner than adults do, these results lend limited support to the hypothesis that retention of conditioned taste aversion may be mediated by a different memory system than the system that mediates retention of more conventional types of learning.