Behaviour: Of mice and man-eaters

The sexual behaviour of female mice can be altered dramatically by almost literally flicking a switch at the periphery of their brain. Disrupting the function of a sensory organ called the vomeronasal organ (VNO) causes female mice to display strikingly masculine sexual behaviours – such as mounting, pelvic thrust and solicitation.
It is thought that sex differences in mammalian behaviour arise as a result of exposure to hormones in the womb, which shape the development of either male- or female-specific neural circuits. The evidence Catherine Dulac and colleagues present in a study. They observed the behaviour of female mice after genetic or physical lesion of the VNO, and report that the mice display sexual and courtship behaviours that are uniquely male. The authors report that the lesioned female mice also show a reduction in female-specific behaviours such as nesting.
These results suggest that, in mice at least, the neural circuitry underlying masculine behaviour surprisingly still exists in adult females. This implies a new model of sex differences in behaviour, in which male and female circuits co-exist in the brains of both sexes and are switched on or off by sensory input such as the pheromones detected by the VNO.

Author contact:

Catherine Dulac (Harvard University, Cambridge, MA, USA)
Tel: +1 617 495 7893; E-mail: dulac@fas.harvard.edu

Marc Breedlove (Michigan State University, East Lansing, MI, USA) N&V author
Tel: +1 517 355 1749; E-mail: breedsm@msu.edu