Creation of generalized genetic models for low and high sensorimotor capacity would be important tools for resolution of this complex trait. As proof-of-principle we estimated phenotypic variation and narrow-sense heritability (h(2)) of sensorimotor capacity in 19 families of genetically heterogeneous N:NIH rats and in 11 strains of inbred rats. Sensorimotor capacity was defined as the time a rat remained on an accelerating rotorod. N:NIH rats recorded variation in rotorod scores that ranged from 3- to 7-fold. The value of h(2), estimated from offspring-parent regression across one generation, was 0.68 for females and 0.74 for males in N:NIH rats. In inbred rats, h(2) was estimated by partitioning phenotypic variation into additive genetic and environmental components and averaged 0.39 in females and 0.48 in males. These results demonstrate a heritable component to sensorimotor capacity sufficient for success in developing contrasting genetic models by divergent artificial selection in rats.
