Abstract

INTRODUCTION

EXPERIMENT 1: Effects of Paced Mating on FOS

EXPERIMENT 2: FOS Responses to III and I Duration

CONCLUSIONS

Discussion
Board

Although an extensive body of information is presently available about the particular areas of the brain which show immediate-early gene expression following mating in the female, little is known about the functional consequences of neural activation within the individual brain areas in which expression occurs. We have previously shown that the expression of c-fos in the preoptic area (POA) and the medial amygdala (mAMYG) following mating is related to the numbers of intromissions received and is dependent upon activity of the pelvic nerve, suggesting that, at least within these areas, the expression of c-fos as well as other IEGs is a marker of sensory input. In order to examine whether c-fos expression can be used as an index of sexual motivation or anticipation, a study was carried out which compared the FOS responses following paced and nonpaced mating; since paced but not nonpaced mating involves active solicitation of mounts from males, cells selectively activated by paced mating might be candidates for areas involved in sexually motivated approaches toward males. In brain, c-fos expression was enhanced in the mAMYG in groups engaging in paced mating above that observed in females receiving the same numbers of intromissions in nonpaced mating tests. No differences between paced and nonpaced treatments were observed in the POA, ventromedial nucleus of the hypothalamus or bed nucleus of the stria terminalis. A second experiment carried out to determine if the differences in FOS- immunoreactivity following paced and nonpaced tests was a consequence of differences in characteristics of the sensory stimuli received indicated that, within the mAMYG, neither interintromission interval nor intromission duration significantly altered c-fos expression. These results demonstrate that cells within the mAMYG are selectively activated in circumstances where the female is actively soliciting sexual contact with males. It seems likely that responsive cells are activated in response to multiple inputs from sensory and motivational afferents and that brain elements controlling the performance of sexual behavior can alter activity sensitivity of sensory elements which govern moment-to-moment alterations in behavior.

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Presentation Number SAerskine0677
Keywords: pacing, c-fos, amygdala, intromissions, sexual motivation