The frequency of intercourse throughout the menstrual cycle is at least moderately correlated with the woman's peak level of testosterone. Castrated male cats remained potent longer if they were introduced to a different female each time. The biological basis of homosexuality may be differences in the organizational affects of prenatal hormones. Human males with spinal cord damage never again have an erection or experience an orgasm. Electrical stimulation of the periaqueductal gray matter facilitates ovulation.
Female rodents lick the anogenital region of their young.
Ultrasonic calls from a rodent pups signals that the pup is cold. If ovariectomized virgin female rats are given a sequence of doses of estradiol and progesterone, they will build brood nests. When monogamous species of voles in which the male and female both care for the offspring are compared to promiscuous species that do not share parental responsibility there are fewer connections between the MPA and the ventral tegmental area in monogamous males. Fos production in the MPA of monogamous males is lower.