[NS16] Sex and the Brain

1. Sex & Gender

• sex : Biological state of being male or female
• Determined by…
  • chromosome
  • hormones
  • body anatomy.

• gender : Set of behaviors or attributes a culture associates with men and women.

• Gender-specific behaviors: nature(biology)? nurture(society)?
  • introspection, upbringing, life experiences, societal expectations, genetics, hormones

gender identity : Our perception of our own gender

1.1. The Genetics of Sex

• genotype
• genetic sex

XY genotype has serious medical consequences:

• X-linked disease is more susceptable to male than female
  • A female with a defective gene on an X chromosome => may experience no negative consequence if the gene on the other X is normal.

  • While any defect in the single X chromosome of a male can lead to a developmental defect (==X-linked disease).

  • red-green color blindness
  • hemophilia
  • Duchenne muscular dystrophy
• X: ~800 genes

• Y: ~50 genes

• sex-determining region of the Y chromosome (SRY)
  • codes for tetis-determining factor (TDF)
  • absent => develops as a female.

Sex Chromosome Abnormalities

• Turner syndrome
  • 빈도 :
  • 증상 :
• Klinefelter syndrome
  • 빈도 :
  • 증상 :

1.2. Sexual Development and Differentiation

The development of gonads.

The Mullarian duct

The Wolffian duct

ㅇㅇ + 그림 하나.

2. Hormonal Control of Sex

2.1. The Principal Male and Female Hormones

• androgens: male hormones
  • e.g. testosterone
• estrogens: female hormones
  • e.g. estradiol
• aromatase: converts testosterone into estradiol.

men also have estrogens, and women also have androgens.
But men have higher concentrations of androgens,
and women have more estrogens.

• Steroid Hormones
  • fatty, easily passing through cell membranes
  • bind to cytosolic receptors => direct access to nucleus and gene expression.

• Direct and indirect effcts of steroid sex hormones on neurons (imp)

• Testes
• Ovaries
  • Hormones : estradiol, progesterone
  • estrous cycle

2.2. The Control of Sex Hormones by the Pituitary and Hypothalamus

1. Anterior pituitary

Gonadotropins: LH and FSH

=> normal sexual development and function

1. Hypothalamus
   1. Release Gonadotropin-releasing hormone (GnRH)
   2. => nyum nyum.
   3. Neural activity affected by : phy
      1. Daily variations of light level
      2. Length of daylight (Seasonal variation)
      3. Melatonin, pineal gland
      4. menstrual cycle?

Effects of LH and FSH ㅇㅇ

3. The Neural Basis of Sexual Behaviors

3.1. Reproductive Organs and Their Control

1. arousal
2. plateau
3. orgasm
4. resolution

nyum nyum

3.2. Mammalian Mating Strategies

• polygamy
  • polygyny
  • monogamy
• monogamy

3.3. The Neurochemistry of Reproductive Behavior

• Studies from voles.

• Studies of humans

3.4. Love, Bonding, and the Human Brain

similar.

vasopressin receptors nyum nyum.

4. Why & How Male and Female Brains Differ

• sexual dimorphisms : A sex-related difference in structure or behavior.