1. Sperm Competition Male rodents leave copulatory plugs Part of ejaculate crystallizes, sticks to cervix Male rodents can also take plugs out Copulatory plug

2. Removing Plugs After several intromissions, males can dislodge existing plugs This ability requires the SNB system Copulatory plug 1 2 –3 4-6

3. Hormonal Basis of Rodent Sex Male = T, Female = E2, P4, Other hormone modulators, e.g.: AVP/OX (social factors) glucocorticoids (stress) cytokines (illness) melatonin (season) prolactin (stress, season, pseudopregnancy)

4. Ovarian Steroids and Receptivity

5. Control of erectile function Smooth muscle vs skeletal muscle Viagra, NO and cGMP Human SNB system

6. PET of male orgasm Holstege et al.(2003) J.Neurosci 23(27):9185 Males with head in scanner Manual stimulation by heterosexual partner no MPOA, BNST Visual cortex activated Amygala deactivated Mesodiencephalic transition zone activated: –Reward circuit –Thalamic ejaculation generator = parvocellular region of the subparafascular nucleus of the thalamus (SPFp)

7. PET of female orgasm Females with head in scanner Manual stimulation by het partner Had anal pressure gauge to detect fakers: –Fake =continous pressure –Real = spike then depression Distinct patterns for “real” vs “faked” orgasm Real = same general pattern as males, but also periaqueductal grey (PAG) in females Fake = all cortical