Climbing sensorimotor skills in Lurcher mutant mice.

Lurcher mutant mice, characterized by massive degeneration of cerebellar granule and Purkinje cells, were compared to normal mice of the same background strain in three sensorimotor learning tasks requiring climbing skills. In the coat-hanger test, Lurcher mutants were deficient in forepaw contact time and four paw latencies. Improvement over time was weak for both groups. For latencies before reaching the halfway point or the top of the diagonal bar in the same apparatus, Lurcher mutants showed gradual improvement while normal mice appeared to lose motivation to perform the task. In a rope-climbing test, a slight reduction in movement time was detected in Lurcher mutants with repeated trials, whereas the performance of normal mice was stable over time. In a water escape pole-climbing test, Lurcher mutants were impaired relative to controls. Both groups decreased the time required before grasping the pole across days of testing. The number of segments climbed was increased in Lurcher mutants across days. These results illustrate that massive cerebellar damage does not eliminate the possibility of acquiring climbing skills, but under some conditions limit performance.