(A–C) Open field locomotor. There was a main effect of genotype for males (p < 0.01) and a gene × interval interaction for females (F11,418 = 4.97; p < 0.001). The B6J males had higher total activity throughout the test session compared with B6N males (p < 0.01). The B6J males also had greater activity in the central zone compared with the B6N males (p < 0.05). During the first 5-min interval, B6J females were significantly more active than B6N females (p < 0.001). The B6N female mice were significantly more active during the next three intervals (p < 0.01), and there was a trend for significance (p < 0.1) in the fifth interval. Data are the least square means ± S.E.M. * p < 0.5, ** p < 0.01, *** p < 0.001.