Impaired motor coordination correlates with persistent multiple climbing fiber innervation in PKCγ mutant mice

It is generally believed that a smooth execution of a compound movement, or motor coordination, requires learning of component movements as well as experience-based refinement of the motor program as a whole. PKCγ mutant mice display impaired motor coordination but intact eyeblink conditioning, a form of component movement learning. Cerebellar long-term depression, a putative cellular mechanism for component motor learning, is also unimpaired. Thus, PKCγ mutant mice are defective in refinement of the motor program. In the accompanying paper, we demonstrate that innervation of multiple climbing fibers onto Purkinje cells persists in adulthood in these mutant mice. We propose that this defective elimination of surplus climbing fibers underlies motor discoordination.