Ontogeny of eyeblink conditioning in the rat: Effects of US intensity and interstimulus interval on delay conditioning

Abstract

Eyeblink conditioning in rat pups (17 or 24 days of age) was examined in two experiments, as a function of US intensity (Experiment 1) and interstimulus interval ([ISI] Experiment 2). In Experiment 1, pups received three sessions of delay conditioning with a tone CS (380 msec, 2.8 kHz, 90 dB [SPL]) and either a1-ora 3-mA periocular shock US. Rats trained on Day 24 showed conditioning that increased as a function of US intensity. Pups trained on Day 17 did not condition with either US intensity level. Experiment 2 examined the effects of conditioning with ISIs of 280, 560, 1,120, or 1,960 msec. Pups trained on PND24 showed a decrement in acquisition with ISIs longer than 280 msec. Seventeen-day-old pups were not conditioned at any of the ISIs used. The results indicate that the age-related development of eyeblink conditioning (Stanton, Freeman, & Skelton, 1992) is not altered under these parametric conditions. © 1993, Psychonomic Society, Inc.. All rights reserved.