Delayed spontaneous alternation in intact and cerebellectomized control and lurcher mutant mice: differential role of cerebellar cortex and deep cerebellar nuclei.

Lurcher mutant (+/Lc) mice exhibit a massive loss of neurons in the cerebellar cortex and in the inferior olivary nucleus while deep cerebellar nuclei are essentially intact. To discriminate the respective participation of the cerebellar cortex and deep structures in learning and memory, the authors subjected 3- to 6-month-old +/Lc mice to a delayed spontaneous alternation task to test their working and long-term spatial memories. Results show that wild type (+/+) mice alternated above chance even after a 1-hr delay between the forced and choice trials, whereas in +/Lc mice, long-term memory was impaired. Cerebellectomized +/+ mice behave as +/Lc mice (working memory was preserved but long-term memory was not), whereas in the cerebellectomized +/Lc mice, both working and long-term memories were altered. These results are discussed in terms of relationships between the cerebellum and the hippocampus.