Spontaneous activity in ASO (n = 7) and wild-type (n = 17) mice at 2, 4, 6, and 8 months of age. Rearing (A), forelimb (B) and hindlimb (C) steps, and time spent grooming (D) were measured. ASO mice were less active in all measures compared with wild-type mice. Values are expressed as mean ± SEM. *p < 0.05 and **p < 0.01, compared with wild-type mice.