Cerebellum and memory: an experimental study in the rat using a passive avoidance conditioning test.

Adult DA/HAN strain rats were submitted to a one-trial passive avoidance conditioning procedure consisting in associating darkness with a nociceptive stimulus. Seven or fourteen days after the one-trial initial experience, they were tested again in order to know whether they had forgotten it or not. The animals were divided into two experimental groups, the rats being either conditioned (COC group) or not (NOC group) before cerebellectomy, and two control groups, the animals being either intact (C group) or sham-operated (SO group). Each group was divided into two subgroups, one being given the retrieval test 7 days and the other 14 days after the initial conditioning. The results show that retention in C, SO and NOC rats was similar whether the animals were tested 7 days or 14 days after the initial one-trial conditioning. Seven days after their initial experience and the cerebellectomy, the retention in COC rats was null while when they were tested 14 days after cerebellar removal these animals had much better scores, significantly higher than 7 days after the lesion. It is concluded that the cerebellum is involved in the consolidation processes of the memory trace but is not the site of memory storage.