EFFECT OF CEREBELLAR GRANULE CELL DEPLETION ON SPATIAL-LEARNING AND MEMORY AND IN AN AVOIDANCE-CONDITIONING TASK - STUDIES IN POSTNATALLY X-IRRADIATED RATS

Rats of the DA/HAN strain (pigmented rats) mere submitted to two exper imental tasks consisting in spatial learning (water escape experiment) and in passive avoidance conditioning. These rats were either totally or partially deprived of their granule cells using two different sche dules of postnatal X-irradiation of the cerebellum. When they were 3 m onths old, the animals were submitted to an initial learning session, followed by a retrieval test seven days later. The scores of the rats which were partially deprived of granule cells appeared similar to tho se of controls, except for a mild deficiency of spatial learning. The learning and retrieval scores of the rats totally deprived of granule cells were similar to those of controls at the passive avoidance condi tioning task, but these animals were unable to accurately learn a spat ial task and showed memory impairments relative to controls. These res ults are discussed in terms of cognitive defects.