Sensory preconditioning effects in young and adult rats.

Compared 64 90- and 64 25-day-old hooded rats on a test of sensory preconditioning (spc). Initially, 2 paired stimuli (s1, s2) were presented, following which s2 was paired with shock. The effects of s1 on 3 measures of lick-rate suppression were taken as indices of spc, these being: standard suppression ratio, lick latency following stimulus onset, and lick latency following stimulus offset. Results are as follows: (a) an spc effect was not demonstrated by the standard suppression ratio, and these data are explained by reference to possible habituation mechanisms or preexposure effects; (b) young ss but not adults showed an spc effect using onset latency; and (c) the reverse held true for the offset latency measure. These latter 2 findings are discussed in terms of differences in associative and discriminative capacities between young and adult ss. (french summary) (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)