Efficacy of lithium chloride in the taste-aversion conditioning of young-adult and old-age rats.

An absolute amount of a LiCl US was administered to 24 young-adult and 24 old-age rats during taste-aversion conditioning to determine whether the superior performance of old-age rats, when a 1% body-weight injection of a LiCl US is administered 3 hr. after a saccharin CS, is due to age-related differences in US intensity or the efficacy of LiCl. The aversion conditioned in old-age rats with a 3-hr. CS-US interval and an absolute amount of LiCl was still significantly greater than that in young adults suggesting that age-related differences in US intensity or the efficacy of LiCl cannot explain the superior performance of old-age rats. Possibly, old-age rats forget the specifics of the CS more than young adults and, thus, older animals show greater stimulus generalization to the substantially different test stimuli.