The effect of hypoxia on the acquisition of a two-way avoidance task in the guinea-pig

Male guinea-pigs learned conditioned two-way shuttle behaviour to acoustic stimuli. Training was given during 5 consecutive days. Two daily training sessions were held with intersession intervals of 120 (Experiment 1) and 60 (Experiment 2) min. In each experiment one group was given post-session hypoxia (H) and another group received no hypoxia (NH). In the NH group the performance during the second session was higher than during the first session on the same day. In the H group this gain was abolished but the course of acquisition was unchanged. The induced amnesia confirmed the selective effect of hypoxia on medium-term memory (MTM) formation previously observed in rats. The results are discussed with reference to the validity of the multistage model of memory formation.