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9 Cards in this Set
- Front
- Back
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Manysex differences in adult brain structure are the result of what?
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- The organizational effects of gonadal steroid hormones, androgen and estrogen, on the fetus while in the uterus, both of which are present in substantially higher concentrations in male fetuses due to the creation of steroids caused by the testicles
- Also, more diverse factors such as: the expression of genes carried on the sex chromosomes, and the discrepancies in maternal treatment between male and female offspring |
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What genes create testes? Where are they located?
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SRY genes, located on the Y chromosome
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What will the brain develop into if testosterone is not present?
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A female brain
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What does developmental masculinization of the brain lead to? Give several examples.
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Significant structural differences in the brain, including:
- different sizes of brain regions - different overall size of collections of cells that constitute nuclei or subnuclei - the growth of dendrites, frequency of synapses, and number of axons (all in specific regions) - astrocytes are more “bushy” in parts of the male brain - microglia are more activated in parts of the male brain |
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How do steroid hormones like testosterone and estradiol change parts of the brain? Give at least one example.
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- By binding to transcription factors that then translocate the cell nucleus to initiate gene transcription
- Ex: Estradiol binds to its receptor and induces the expression of the gene for cyclooxygenase, which mediates the production of prostaglandin (PGE2). PGE2 causes the preoptic area of the male brain to have twice the density of excitatory synapses as the female brain, which is positively correlated with male sexual behavior. |
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What is the amygdala and how is it affected by steroid hormones?
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- Processes emotions and regulates social play behavior by juveniles (rough-and-tumble play), which differs in males and females
- Endocannabinoids (ligands for the receptors activated by marijuana) suppress cell genesis in the amygdala in males, leading to an increase in rough-and-tumble play (which also occurs if females are exposed to higher levels of endocannabinoids early on) |
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In terms of the mosaic brain, label and describe two well-known examples of “natural experiments”. Write out full names, not just the acronyms.
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- Congenital adrenal hyperplasia (CAH): adrenal glands produce excessive androgens during fetal development
- Complete androgen insensitivity syndrome (CAIS): a mutation in the androgen receptor makes it incapable of binding testosterone and other androgens - Both of these result in somebody with an XX or XY chromosome appearing outwardly as the opposite sex |
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In the case of CAIS, does brain sex match gonadal sex? What does this mean?
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No. This means that although the chromosomes in the person’s DNA (brain) says that they are a girl or a boy (XX or XY), how their outward genitalia develop is how they see themselves (e.g. CAIS individuals who have XY genes develop outwardly as girls, and consistently identify as girls even though their genes tell them they’re not)
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Why is it wrong to say there is a “male brain” and a “female brain”?
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Because the brain is not uniformly “male” or “female”, it is a combination of both masculinized parts and feminized parts; males have parts that are more masculinized than females’ are, and females have parts that are more feminized than males’ are, but there are many more parts of the brain that show no consistent differences between sexes
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