Sex and Sex Differences (ch 12)

Sex Differences

early in development established and serve the need of reproductive strategies

Gonadal Hormones

mediate early changes in developing brain to assure activation of same circuits by the same hormones in adulthood will product appropriate reproductive behaviors

What are the Gonadal Hormones?

testosterone and estradiol

Evolutionary Perspective

gender variability optimizes adaption by allowing us to maximize our exploitation or resources available and reproductive success at the population level

Reproductive Behavior

behaviors for attracting mates (copulation)

Sex Determination

process by which decision is made for fetus to be male/female

X Chromosome

female

Y Chromosome

male

Sry

single gene on Y chromosome and directs formation of testes

Sexual Differentiation

process by which individuals develop male/female bodies and behaviors

Mullerian Ducts

develop into female reproductive organs

Wolffian Ducts

develop into male reproductive organs

OAH

framework to describe two sensitive periods for gonadal steriods influences in sexual differentiation 

Organization Effects of OAH

prenatal, long-lasting, masculization for males, females stop sensitivity to androgens

Activational Effects of OAH

during puberty, temporary, limited by organizational effects

What accounts of OAH?

changes to key brain circuitry

Sexual Dimorphism

marked sex differences in appearance in males vs. females

Preoptic Area (POA)

larger in males relative to females (due to testosterone)

SDN-POA

lesions disrupt ovulatory/copulatory behaviors

Key CNS altered by gonadal steriods

SDN-POA, AVPV-POA, pBST, SNB

SDN-POA

sexually dimorphic nucleus of preoptic area

AVPV-POA

anteroventral periventricular nucleus of preoptic area

pBST

principal nucleus of bed nuclei of stria terminals

SNB

spinal cord, nucleus bulbocavernosus

Gonadal steroids on Hippocampus + Amygdala

emotionality, aspects of learning and memory, stress responsiveness, affiliative behaviors

INAH-3

larger in men vs. females, larger in straight men vs. gay men

Androgens

required for masculization, gay women show exposure to androgens during first sensitive periods