SEARCHING FOR SEX-DIFFERENCES IN THE VOMERONASAL PATHWAY

The sexual differentiation of brain and behavior is reviewed from the findings of sex differences in the vomeronasal pathway. A motivational approach to sex differences in reproductive behavior is stressed by t aking into account that sex differences are present in neural networks : from the receptor organ (the vomeronasal organ) to effector nuclei. Sex differences in the brain appear in two morphological patterns. In one, the male presents greater morphological measurements than the fem ale; in the other, the opposite occurs, These two morphological patter ns are actively differentiated by gonadal steroids. The functional sig nificance of these two morphological patterns is addressed. Moreover, since the GABAA receptor is involved in the organization of sex differ ences in vomeronasal structures such as the accessory olfactory bulb a nd in maternal behavior, the role of membrane mechanisms, 5 alpha redu ced hormones, and neurosteroids in the sexual differentiation process is discussed. (C) 1996 Academic Press.