Older MPS IIIB mice are impaired on the rocking rotarod.

Mean duration (in seconds) of the time spent on the rocking rotarod as a function of increasing ages (days) for MPS IIIB (open squares) and heterozygous (filled diamonds) control mice. No performance differences were observed between groups on the rocking rotarod in the younger cohort of mice (left panel). In contrast, an ANOVA conducted on the first 4 data points from the older cohort of mice (right panel) revealed a significant main effect of Genotype (p = 0.030), thus showing, in general, that the older MPS IIIB mice, remained on the rod for a significantly shorter time compared to the heterozygous control mice. Differences between groups were greatest when the mice were tested at 244 (*p = 0.013) and 302 (†p = 0.034) days of age. Even greater deficits were observed in the MPS IIIB mice when they were tested at older ages although small sample sizes resulting from high mortality rates in the MPS IIIB mice precluded formal statistical analyses. Numbers in parentheses represent sample sizes at specific ages of testing. The dotted line indicates that the last two test sessions (327 and 372 days) were not included in the overall ANOVA since sample sizes were so small due to increased mortality.