Michael J Baum

..Finally, we review experiments that raise the possibility that body odorants detected by the main olfactory system contribute to mate recognition in humans...

..Evidence is also reviewed suggesting that perinatal estradiol biosynthesis and action in the female's nervous system may contribute to the development of female-typical sexual behavior...

..I also argue, however, that results of animal studies can, at best, provide only indirect insights into the neuroendocrine determinants of human gender identity and role behaviors...

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..However, we failed to corroborate the recent claim that VNO signaling normally inhibits the activity of neural circuitry controlling the expression of male-typical mating behavior by female mice...

..The presence of a direct MOB-to-medial amygdala pathway in mice and other mammals could enable volatile, opposite-sex pheromones to gain privileged access to diencephalic structures that control mate recognition and reproduction...

..Our results suggest that the Me is a critical segment of the olfactory circuit that controls both mate recognition and mating behavior in the female mouse...

..However, once direct nasal contact is made with female urine, VNO inputs further activate forebrain mechanisms that amplify the reward salience of this stimulus for the male mouse...

..Male-typical hypothalamic processing of conspecifics' body odorants may determine males' normal preference to seek out odors emitted by female conspecifics, leading to mating and successful reproduction...

..Main olfactory-MeA-AOB signaling may motivate approach behaviour to opposite-sex pheromonal signals that ensure successful reproduction...

..Future studies will determine whether MOE or VNO signaling, or both types of input, drive the sexually dimorphic response of the AOB to volatile opposite-sex odours and whether this AOB response contributes to reproductive success...

..Thus, estradiol enhanced detection thresholds for male urine in a sex-specific manner, and this enhanced sensitivity in females was correlated with altered odor-sampling behavior...

..Estrogen-sensitive neurons in the VMH appear to play a central role in female-typical neural processing of odor inputs leading to a preference to seek out a male sex partner, in addition to facilitating females' sexual receptivity...

..Our results suggest that the incentive value of opposite-sex (female) volatile urinary odors which are initially detected by the main olfactory system is enhanced when they are further processed by the male's AOB...

..This arrangement may be related to the ability of social experience to modify the response of mice to volatile pheromones detected by the main olfactory system...

..These data suggest that ferrets could use anal scent gland secretions in mate recognition and that seasonal increases in circulating sex steroid hormones increase ferrets' responsiveness to low concentrations of these odors...

..These results suggest that activity in distal segments of the VNO-accessory olfactory pathway, in addition to the mesolimbic dopamine reward system, can be conditioned to respond to non-odor cues...

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..Our results suggest that the VNO is not required for sex discrimination but instead detects the nonvolatile components of opposite-sex urine that may be used to help prolong contact with individuals that produce these chemosignals...

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..In ferrets of both sexes, volatile body odourants that are detected by the main as opposed to the vomeronasal-AOB accessory olfactory system may play a critical role in mate identification...

..This functional sex difference was inversely correlated with the present observation that glomerular density, number and area were greater in the caudal MOB of male than female ferrets...

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..Understanding of the hormonal mechanisms of these behaviors, and of relevance to humans, is needed to develop biologically plausible hypotheses regarding the potential effects of hormonally active chemicals in humans...

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..By contrast, both the main and accessory olfactory systems contribute to female sexual receptivity in female mice...

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..These results thus further confirm the important role of estradiol in sexually related behavioral responses in male mice...

..The proposed studies should provide new information about the contribution of estradiol to the development of essential aspects of female-typical neural and behavioral functions. ..

..Affirmation of a perinatal role for estradiol in brain sexual differentiation in female mice would raise the question of whether estradiol plays a similar role in female-typical psychosexual differentiation in women. ..

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..Understanding how the male and female nervous systems process reproductive odors differently in a higher mammal like the ferret could provide new insights into sexually dimorphic brain-behavior relationships in man. ..

..The results of these experiments should identify sites in a well-characterized anatomical pathway at which sex hormones and social experience affect the detection and/or processing of olfactory signals. ..

..Affirmation of a perinatal role for estradiol in brain sexual differentiation in female mice would raise the question of whether estradiol plays a similar role in female-typical psychosexual differentiation in women. ..