ANALYSIS OF 2 MEASURES OF PAW PREFERENCE IN A LARGE POPULATION OF INBRED MICE

Two measures of lateralized forelimb usage, the Collins paw preference test and the Lateral Paw Preference test (LPP), were tested in 693 mi ce of 29 inbred strains and F-1 crosses, and 2 embryo transfer groups. These strains included NZB, SM, and the NXSM recombinant inbred (RI) strains; RF and the NXRF RI strains; BXSB and the Y-consomic BXSB-Yaa +; DBA/2 and F(1)s of DBA/2 and BXSB and BXSB-Yaa; and NZB x NZW F(1)s . The findings indicated that (1) the Collins and LPP tests were indep endent in terms of direction of lateralization, (2) there were signifi cant population biases of 60.96% rightward on the LPP test, and 54.39% leftward on the Collins test, (3) there were significant strain diffe rences on measures of absolute asymmetry on both tests, (4) there were strain differences for direction of asymmetry on the Collins test, bu t not on LPP, (5) on the basis of the NXSM RI strains, 3 genetic loci contribute to strength of laterality on the LPP test, and (6) there wa s a strong correlation among strain means for strength of lateralizati on on the two tests. These results extend previous findings on the str ength and direction of laterality, showing that two independent system s for direction of laterality may depend on the same mechanism for mag nitude, and establish that multiple factors of handedness, previously identified in humans and other primates, also exist in mice.