GENDER AND BRAIN - PowerPoint PPT Presentation

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  2. Nature or nurture?

  3. Difference in Solving Intellectual Problems • Boys and girls different way of developing brains. • Difference between boys and girls lies in patterns of ability rather than in overall level of intelligence (IQ).

  4. No Differences Between Boys and Girls • Vocabulary • Reasoning

  5. Boys vs. Girls? • Which one is the same as the one on the left?

  6. Boys vs. Girls? • Mathematical Reasoning

  7. Boys vs. Girls? • Find the “key” in one of the pictures?

  8. Boys vs. Girls? • Name the word start from “L”.

  9. Boys vs. Girls? • Can you find the hidden shape in here?

  10. Boys vs. Girls? • Calculation

  11. Boys vs. Girls? • Which one is the same shape as the left most one. Can you tell from the different angle?

  12. Boys vs. Girls? • When you fold a paper and punch a hole and open the paper, where the punch holes will be?

  13. Boys vs. Girls? • Put the small pegs into the matching holes.

  14. Boys vs. Girls? • Hit the target.

  15. Girls Boys

  16. AphasiasSpeech Disorders

  17. Phonological Processing Sex Difference Shaywitz 95

  18. Conclusion • Differences between Boys and Girls in the brains reflect in many ways from the very beginning of the lives. • Major differences between boys and girls in brain functions are in the patterns of ability. Nature/god made both boys and girls so well!

  19. Brain size

  20. Brain size • At birth, the average brain of boys is between 12-20% larger • However, when the size of the brain is compared to body weight at this age, there is almost no difference between boys and girls • Many recent claims have been made that the corpus callosum is bigger and more developed in women than in men.

  21. Brain size • studies show that human male brains are, on average, approximately 10 percent larger than female brains. Certain brain areas in women, however, contain more nerve cells.

  22. Hypothalamus • Preoptic Area • involved in mating behavior. • males of several species the preoptic area is greater in volume, in cross-sectional area and in the number of cells. • In men, this area is about 2.2 times larger than in women and contains 2 times more cells. • after a person is 4 years old: decrease in the number of cells in this nucleus in girls.

  23. Suprachiasmatic Nucleus of the Hypothalamus • area of the hypothalamus is involved with circadian rhythms and reproduction cycles. • shape: in males, this nucleus is shaped like a sphere; in females it is more elongated. • No difference in number of cells or volume • ?shape influences the connections that this area makes with other areas of the brain, especially the other areas of the hypothalamus.

  24. David Reimer, boy or girl?

  25. John Money, Johns Hopkins University

  26. “In the light of hermaphroditic evidence ” he wrote in a 1955 paper that would become a classic in the field of sexual development, “it is no longer possible to attribute psychological maleness or femaleness to chromosomal, gonadal or hormonal origins. . . . The evidence of hermaphroditism lends support to a conception that, psychologically, sexuality is undifferentiated at birth and that it becomes differentiated as masculine or feminine in the course of the various experiences of growing up.”

  27. Milton Diamond, University of Hawaii

  28. “To support [such a] theory,” Diamond wrote, “we have been presented with no instance of a normal individual appearing as an unequivocal male and being reared successfully as a female.”

  29. The twins • At 7 months, botched circumscision • Sex reassignment • Castration at 21 months • Intensive socialization to female gender • Estrogen treatment at age 12

  30. Money declared the experiment a success • Published book (1974) and paper (1975) • Thousands of kids around the world given gender reassignment based on this one • Clear evidence of sex difference in brain anatomy not until 1977

  31. Long-term follow-up • Diamond published description of gender re-re-assignment and successful adjustment • Colapinto wrote article and book (2000) • Additional case of ablatio penis, kept female identity but “lesbian” preference

  32. But • Although treated like a girl • didn't like playing with the other girls – • he didn't move like one either. • got into schoolyard fistfights. • other kids called him names like "caveman," "freak" and "it."

  33. But • Money wrote: "The child's behaviour is so clearly that of an active little girl and so different from the boyish ways of her twin brother." • The twin brother, Brian, remembered it differently: "The only difference between him and I was he had longer hair."

  34. Father told him • Tried to commit suicide three times • Four rounds of plastic surgery

  35. Eventually married • Went public • Suicided last year

  36. Consider this Diamond interview • I: Are you a girl? • C: Yes • I: When you grow up, will you be a Mommy or a Daddy? • C: Mommy. • I: Could you grow up to be a daddy? • C: No. • I: Are there any good things about being a boy? • C: No.

  37. Consider this Diamond interview • I: Are there things that you don't like about being a boy? • C: Yes. • I: Tell me some of the things that you don't like about being a boy? • C: Because I hate it. 'cause we get to do stupid, sitting down. • I: Do you think it is better to be a boy or a girl? • C: Girl.

  38. Consider this Diamond interview • I: Why? • C: Because it's fun - they sit around and talk. • I: In your mind, do you ever think that you would like to be a girl? • C: Yes.

  39. Info on the interview • Child is a boy • Child is 4 • Raised as a boy • Presently thinking he is a girl or should be • What will he grow up to be?

  40. Twin studies

  41. Vilain and his mice • "It's quite possible that sexual identity and physical attraction is 'hard-wired' by the brain," he said. "If we accept this concept, we must dismiss the myth that homosexuality is a 'choice' and examine our civil legal system accordingly."

  42. Vilain and his mice • What he found: • found 54 genes produced in different amounts in male and female mouse brains, prior to hormonal influence. • 18 of the genes were produced at higher levels in the male brains; • 36 were produced at higher levels in the female brains.

  43. Add a male an average of 2.6 times, and received an average of 1.8 scars Guess what: significantly lower levels of dopamine and serotonin in areas of the amygdala Add a female Female rats did not attack other rats, and were not attacked themselves. Jonathan Toot and his wandering rats

  44. "The data show that males are involved in more fights than females," they say, "suggesting increased aggression is influenced by a Y-chromosomal effect that decreases amygdala serotonin." The researchers speculate that testosterone levels also contribute to males' increased aggression. open up the possibility of being able to identify the chromosome markers in high-risk males, and of trying to manipulate their levels of serotonin, through diet, exercise, or medication.a long way down the road, but this is the start." Jonathan Toot and his wandering rats

  45. More mice • "The effect of ginkgo biloba on aggression was remarkable," the researchers say. "When 0.1 ml of ginkgo biloba was administered to MAOA knockout mice, their aggressive behavior in resident-intruder confrontations was reduced significantly." The substance had no effect on the mice's nonsocial, investigative, defensive, or movement behaviors, indicating that effects were not due simply to sedation.

  46. 57 men and 59 women Ruben Gur and colleagues performed MRI • The researchers measured • the volume of the amygdala, • hippocampus, and • other limbic areas associated with emotional arousal, • as compared to the volume of orbital frontal brain regions that exert control over emotional responses

  47. 57 men and 59 women Ruben Gur and colleagues performed MRI • Results: • Same for: • the volume of the amygdala, • hippocampus, and • other limbic areas associated with emotional arousal, • But women had significantly larger orbital frontal cortex volume than men.

  48. Ruben Gur and colleagues performed MRI • Conclusions: • "Because men and women differ in the way they process the emotions associated with perception, experience, expression, and most particularly in aggression," the researchers say, "our belief is that the proportional difference in size in the region of the brain that governs behavior, compared to the region related to impulsiveness, may be a major factor in determining what is often considered 'gender-related' behavior."