Spatial ability of XY sex-reversed female mice

Perinatal gonadal hormones significantly affect subsequent sex differences in reproductive and non-reproductive behaviors in rodents. However, the inf luence of the sex chromosomes on these behaviors has been largely ignored. To assess the influence of the non-pseudoautosomal region of the Y chromoso me, C57BL/JEi male and female mice and mice from the C57BL/6JEi-Y-POS conso mic strain were given behavioral tests known to distinguish males from fema les. The C57BL/6JEi-YPOS strain contains sex-reversed XY-females which, whe n compared to their XX-female siblings, allow assessment of the influence o f the Y chromosome in a female phenotype. XX-females and XY-females did not differ on open-field activity, the Lashley maze, or active avoidance learn ing, but XY-females were significantly better than XX-females on the Morris hidden platform spatial maze. These findings suggest that males may have b oth a genetic and a hormonal mechanism to ensure visuospatial superiority. (C) 2000 Elsevier Science B.V. All rights reserved.