Further characterization of repetitive behavior in C58 mice: developmental trajectory and effects of environmental enrichment.

Aberrant repetitive behaviors are commonly observed in a variety of neurodevelopmental, neurological, and neuropsychiatric disorders. Little is known about the specific neurobiological mechanisms that underlie such behaviors, however, and effective treatments are lacking. Valid animal models can aid substantially in identifying pathophysiological factors mediating aberrant repetitive behavior and aid in treatment development. The C58 inbred mouse strain is a particularly promising model, and we have further characterized its repetitive behavior phenotype. Compared to C57BL/6 mice, C58 mice exhibit high rates of spontaneous hindlimb jumping and backward somersaulting reaching adult frequencies by 5 weeks post-weaning and adult temporal organization by 2 weeks post-weaning. The development of repetitive behavior in C58 mice was markedly attenuated by rearing these mice in larger, more complex environments. In addition to characterizing repetitive motor behavior, we also assessed related forms of inflexible behavior that reflect restricted and perseverative responding. Contrary to our hypothesis, C58 mice did not exhibit increased marble burying nor did they display reduced exploratory behavior in the holeboard task. The C58 strain appears to be a very useful model for the repetitive motor behavior characteristic of a number of clinical disorders. As an inbred mouse strain, studies using the C58 model can take full advantage of the tool kit of modern genetics and molecular neuroscience. This technical advantage makes the model a compelling choice for use in studies designed to elucidate the etiology and pathophysiology of aberrant repetitive behavior. Such findings should, in turn, translate into effective new treatments.