Handedness in mice: comparison across eleven inbred strains.

Screening for handedness was performed in 11 inbred strains of mice. Direction and degree of handedness were measured for both males and females in each strain. The data show that there are almost as many right- as left-handed subjects and no strain could be classified as right- or left-handed. Females, however, tend to be more strongly lateralized than males. The range of variation for degree of handedness is pronounced between strains. These results thus suggest that degree of handedness would be the relevant variable in a genetic analysis of handedness in mice. They are in agreement with Collins' previous results showing a response to selection for degree, but not for direction, of handedness.