Phenotypic variation in sensorimotor performance among eleven inbred rat strains.

As a first step toward identifying the genes that determine sensorimotor ability (motor coordination) we subjected 11 inbred strains of rats to three different tests for this trait. Rats were tested at 13 wk of age to determine how long they could remain on 1) a rotating cylinder as the velocity of rotation increased every 5 s (1-direction rotation test), 2) a rotating cylinder that reversed direction every 5 s and increased velocity every 10 s (2-direction rotation test), and 3) a platform that was tilted 2° every 5 s from 22 to 47° (tilt test). On all three tests, rats of the PVG strain demonstrated the greatest sensorimotor ability. In contrast, rats of the MNS strain were most often represented among the group of strains that demonstrated the lowest performance on all tests. Considering all three tests, there was a 3- to 13-fold range in sensorimotor performance between the highest and lowest strains. This large divergence between the highest and lowest strains provides a genetic model that can be used to identify intermediate phenotypes and quantitative trait loci that contribute to sensorimotor ability.