The development of swimming behavior in the neurological mutant weaver mouse.

Weaver (wv/wv) mice have well-specified ontogenetic defects in both the cerebellum and striatum, but have not previously been evaluated systematically for patterns of motor development. In this study, the effects of the weaver mutation were evaluated through an examination of swimming behavior over the first 3 postnatal weeks. Detailed movement analyses of individual limb movements as well as interlimb coordination were used to evaluate the effects of the weaver mutation. Weaver mutant mice displayed a developmental lag in terms of swimming style relative to controls. They also displayed a generalized slowness in limb movements during the swim, which correlated with the developmental onset of use of a particular limb during the swim. However, basic motor patterns in weaver swimming continue to exhibit good overall coordination through the 3rd postnatal week, even though locomotor ataxia has become pronounced by this time. Our results indicate that specific and limited alterations in movement can be traced to very early in development (postnatal Day 3) in weaver mutant mice, a time at which the earliest biochemical and neuroanatomical deficits in these animals have been established. Our results also emphasize the need for systematic contextual analyses of movement to understand interlocking processes both in movement ontogeny and its disorders.