PSYC 5100 TEST 3 (brain structure)

Sex diff in brain structure

undifferentiated stage

0-7 week gestation; male and female embryos are indistinguishable

y chromosome and testes formation

8 weeks; y chromosome triggers antigen synthesis leading to testes development; testes produce testosterone which influences brain organization

undifferentiated stage

0-7 week gestation; male and female embryos are indistinguishable

y chromosome and testes formation

8 weeks; y chromosome triggers antigen synthesis leading to testes development; testes produce testosterone which influences brain organization

critical period for testosterone effects

exposure to testosterone outside of the 8 week window has less impact on brain development; influences sexuality, aggression, and other behaviors

brain structure diff in males

slightly larger overall brain volume; larger angular gyri (goldstein)

brain structure diff in females

more proportionally gray matter; larger frontal lobes (goldstein)

controversy for brain structure diffs

some studies suggest methodological differences may impact findings

diffusion tensor imaging

tracks water movement to analyze white matter

sex differences in connectivity

males have more within-hemispheric connections (perception + coordinated action); women have more between-hemispheric connections (communication between analytical and intuitive processing models)

genotype

an individuals genetic sequence

phenotype

an individuals traits the result from genetic expression through the lifetime

the hypothalamus likely contributes to

sexuality/reproduction

classic view

hormones drive sex differentiation

modern view

hormones plus experience (lifetime including gestation) drive sex differentiation

gray

cell bodies, computation

white

cell axons, connection

McCarthy and Arnold created

transgenic mice to line common sex differences to genes, hormones, or both

classic view of M&A

linear hormone driven

post-modern view of M&A

parallel, mulitfaced; tied to genetic throughout lifetime, sex differentiation effects are tissue and organ specific, each sex difference is the result of a balance of diverging and compensating physiological processes