Acquisition and retention of multidirectional escape behavior in preweanling rats

Abstract

The shock-escape behavior of preweanling rats in a multidirectional escape situation was examined in 3 experiments. In Experiment I, 5-, 7-, 9-, and 11-day-old rats were given shock-escape training on each of 3 days. Rats younger than 7 days of age did not improve escape responding within or over sessions. Animals 7 days of age and older, however, showed both an intrasession improvement and an intersession improvement that could not be attributed solely to maturation. In Experiment II, the escape behavior of 3-, 5-, and 7-day-old was examined in an apparatus modified to take into account the poor locomotor abilities of these animals. They were given escape training on 3 successive days. Again; no within-session improvement was found in rats under 7 days of age. However, an intersession improvement was found in rats whose training began at 5 days of age. This improvement was due to maturation and did not reflect a cumulative effect of training. Experiment III, like Experiment I, demonstrated that the intersession improvement in the older rats was not simply a maturation effect. It also demonstrated that the improvement could not be attributed to the stress of prior handling, shock, or body temperature loss, but was, rather, a retention effect. These results support the contention that the emergence of memory is task specific.