Vertical jumping and signaled avoidance

Intra-amygdala ZIP injections impair the memory of learned active avoidance responses and attenuate conditioned taste-aversion acquisition in rats

We have investigated the effect of protein kinase Mzeta (PKMζ) inhibition in the basolateral amygdala (BLA) upon the retention of a nonspatial learned active avoidance response and conditioned taste-aversion (CTA) acquisition in rats. ZIP (10 nmol/μL) injected into the BLA 24 h after training impaired retention of a learned avoidance-jumping response assessed 7 d later when compared with control groups injected with scrambled-ZIP. Nevertheless, a retraining session applied 24 h later indicated no differences between the groups. Additionally, a similar ZIP injection into the BLA during the conditioned stimulus-unconditioned stimulus (CS-US) interval attenuated CTA acquisition. These findings support the BLA PKMζ role in various forms of memory.

Early learning failure impairs adult learning in rats

Early life experiences may affect adult learning ability. In two experiments we tested the effect of early learning failure on adult performance in Wistar rats. In the first experiment 17-day-old rats (PN17), but not 25-day-old rats (PN25), trained in a hidden platform water maze task showed deficits in tone-shock avoidance learning when they were 3-months-old. The second experiment, which included random-platform and non-platform control groups, confirmed the effect of early (PN18) spatial learning failure on adult avoidance learning. However, post-weaning training (PN25) without platform also tended to induce adult learning deficits as long as the adult task difficulty was increased. The older non-platform group did not differ from the impaired group which received early training in a fixed hidden platform task. The results are discussed in terms of the relevance of early learning outcome and developmental stage on adult general learning deficits which may be related to the learned helplessness phenomenon and developmental neural plasticity.

Avoidance training using an incremental vertical jump response in rats

A procedure is described for conditioning a vertical jump avoidance response in rats. Employing an auditory signal and gradually increasing the height of the response platform, rats showed rapid acquisition of a jump response to avoid shock. While the average maximum height of the jump response increased between original training and retraining 7 days later, retraining 40 days later resulted in stable responding that was consistent with the first retraining session.