Dissociation of Pre-Exposure Effects on Acquisition of Delay vs. Trace Eyeblink Conditioning in Developing Rats
It is well known that stimulus pre-exposure affects subsequent learning in Pavlovian conditioning paradigms. Recent studies have demonstrated interesting differences in the ontogeny of two types of pre-exposure effects, savings and learned irrelevance (LIR), by assessing the acquisition of delay eyeblink conditioning (EBC) in young rats. Stanton et al. (1998) observed savings of learning between days 17 and 20 in young rats, but LIR was not evident until days 27-30 (Rush et al., 2001). Since acquisition of delay depends on maturation of the cerebellum and brainstem (Freeman et al., 1995), whereas LIR involves entorhinal cortex (Allen & Gluck, 2002), this suggests the later maturation of entorhinal learning circuits and function.
Claflin, D. I.,
& Buffington, M. L.
(2004). Dissociation of Pre-Exposure Effects on Acquisition of Delay vs. Trace Eyeblink Conditioning in Developing Rats. Integrative Psychological and Behavioral Science, 39 (1), 43-80.