The Female Brain (28 page)

The good news is that treatment is available, and it is effective. The brain chemicals such as serotonin that help support mood and well-being are running low after giving birth and the postpartum brains in depressed moms have a deficit. Medications and hormones can help return their brains to normal. A consensus among experts in postpartum depression recommends—for women with severe symptoms—antidepressant medication combined with other treatment modalities, such as supportive talk therapy.

APPENDIX THREE

The Female Brain and
Sexual Orientation

H
OW DOES SEXUAL
orientation get wired in the female brain? There are many variations in the female brain that lead to individual skill sets and behaviors. Our genetic variations and the hormones present in our brains during fetal development are the cornerstone of the female brain. Life experiences then play upon our particular female brain circuits to reenforce individual differences. One variation that appears on a continuum in females is same-sex romantic attraction. This is estimated to occur in five to ten percent of the female population.

The female brain is only half as likely to be wired for same-sex attraction as is the male brain. Therefore men are twice as likely as women to be gay. Biologically, genetic variations and hormonal exposure in both male and female brains are thought to lead to same-sex attraction, but the origins in women appear to be different than in men. Most brain studies have been done on the difference between gay and straight males, and only recently have studies in females begun to emerge. Sexual orientation in females occurs along more of a continuum than in males, with females reporting more bisexual interests. Psychosocial studies have also shown that gay women have higher self-esteem and quality of life than do gay men. This may be because it is socially easier to be a gay woman than a gay man.

Sexual orientation does not appear to be a matter of conscious self-labeling but a matter of brain wiring. Several family and twin studies provide clear evidence for a genetic component to both male and female sexual orientation. We know that prenatal exposure to an opposite-sex hormonal environment, like testosterone in a genetically female brain, leads the nervous system and brain circuits to develop along more male-typical lines. This prenatal hormonal environment has enduring effects on behavioral traits like rough-and-tumble play and sexual attraction.

Core gender identity and sexual orientation were assessed in one study along with recalled childhood gender role behavior in women who were exposed to higher levels of testosterone in utero. They recalled more male-typical play behavior as children than did women not exposed to fetal testosterone. These women also reported more same-sex attraction and were more likely to be gay or bisexual.

One study examined brain-wiring differences, as indicated by the “startle response” between gay versus straight women. They found that gay women had a lower startle response—in a similar range to most men—indicating brain-wiring differences between straight and gay women. Gay versus straight women showed a less sensitive auditory response—a male-typical pattern. Female brains usually perform better than male brains in tests of verbal fluency. Gay women showed opposite-sex shifts in their verbal fluency scores—scoring in a range intermediate between males and females. Gay women identified as “butch” versus “femme” showed a range of scores intermediate between males and females. And straight women scored better overall in verbal fluency tests than their gay female counterparts. This indicates that these differences in brain circuitry are on a continuum in the female brain. These scientific findings indicate that the wiring of the female brain for sexual orientation occurs during fetal development, following the blueprint of that individual’s genes and sex hormones. The behavioral expression of her brain wiring will then be influenced and shaped by environment and culture.

NOTES

The chapter notes are the result of many years of research, thought, and synthesis of ideas. I have gathered the work of many scientists in various disciplines in order to arrive at this understanding of the female brain. As a result, some notes contain multiple references, reflecting the various sources I used to arrive at the theory expressed in the text.

Here in the notes section where there are multiple authors of a paper or book, I have listed only the first author and the year of publication. Where more than one reference is used, I have arranged them in chronological order. For the full citation, please see the References section.

INTRODUCTION: W
HAT
M
AKES
U
S
W
OMEN

“…perception, thoughts, feelings, and emotions.”:
Nishida 2005; Orzhekhovskaia 2005; Prkachin 2004; see Chapter 6, “Emotion.”

“…in women compared with men.”:
Blehar 2003; Madden 2000; Weissman 1993.

“…premenstrual brain syndrome.”:
Schmidt 1998; see Chapter 2, “Teen Girl Brain.”

“…25 percent every month.”:
Woolley 1996, 2002.

“…or bite someone’s head off.”:
See Chapter 2, “Teen Girl Brain.”

“…brain sensitivities to stress and conflict.”:
Shors 2006.

“…activated to complete the task.”:
Bell 2006; Jordan 2002.

“…by using different brain circuits.”:
Tranel 2005; Jordan 2002.

“…11 percent more neurons than men.”:
Witelson 1995; see also: Knaus 2006; Plante 2006; Wager 2003.

“…language and observing emotions in others.”:
Baron-Cohen 2005; Goldstein 2005; Giedd 1996.

“…four times on her hottest days.”:
See Chapters 4, “Sex,” and 7, “The Mature Female Brain.”

“…as just two people talking.”:
See Chapter 3, “Love and Trust.”

“…triggers aggression—the amygdala.”:
Cahill 2005; Giedd 1996; Witelson 1995.

“…try anything to defuse conflict.”:
Campbell 2005; see Chapter 6, “Emotion.”

“…stress experienced in the ancient wild.”:
See Chapters 2, “Teen Girl Brain,” 3, “Love and Trust,” and 5, “The Mommy Brain.”

“…endangered by impending catastrophe.”:
See Chapters 2, “Teen Girl Brain,” 3, “Love and Trust,” and 5, “The Mommy Brain.”

“…such as math and science.”:
Blinkhorn 2005; Cherney 2005; Haier 2005; Jausovec 2005.

“…are not plausibly, culturally determined.”:
Summers 2005.

“…scientific capacity is nonexistent.”:
Spelke 2005.

“…for hours of computer time.”:
See Chapter 2, “Teen Girl Brain.”

“…careers because of lack of aptitude.”:
Lawrence 2003, 2006; Babcock 2004.

“…the ability to defuse conflict.”:
See Chapter 6, “Emotion.”

ONE: T
HE
B
IRTH OF THE
F
EMALE
B
RAIN

“…hardwired into the animal brain.”:
Hines 2002.

“…both genes and sex hormones.”:
Arnold 2004. The tiny testicles in the eight-week-old male fetus begin to pump out huge amounts of testosterone that marinates the brain, changing the female-type brain circuits into male brain circuits. Many months later, by the time of birth, the brain is either a female brain or a male brain.

“…areas that process emotion.”:
See Chapter 6, “Emotion.”

“…communication than he will.”:
Tannen 1990.

“…baby to do is study faces.”:
McClure 2000.

“…will not increase at all.”:
Leeb 2004.

“…symbiosis with their mothers.”:
Silverman 2003.

“…faster, by one to two years.”:
McClure 2000.

“…they are forbidden to touch.”:
Mumme 1996.

“…and hearing human emotional tones.”:
Schirmer 2005, 2004, 2003.

“…a baby girl’s behavior.”:
Baron-Cohen 2005.

“…their mothers than do boys.”:
Weinberg 1999.

“…face—than male newborns do.”:
McClure 2000.

“…those who look sad or hurt.”:
McClure 2000.

“…twenty-four months long for girls.”:
Grumbach 2005 personal communication; Soldin 2005.

“…brain for reproductive purposes.”:
Grumbach 2005.

“…mother’s nervous system into her own.”:
Leckman 2004; Zhang 2006.

“…a fearful, anxious one.”:
Meaney 2005; see Chapter 5, “The Mommy Brain.”

“…nurturing their mothers are.”:
Cameron 2005; Cooke 2005; de Kloet 2005; Fish 2004; Zimmerberg 2004; Kinnunen 2003; Champagne 2001; Meaney 2001; Francis 1999.

“…females and nonhuman primates.”:
Kajantie 2006; Capitanio 2005; Kaiser 2005; Gutteling 2005; Wallen 2005; Huot 2004; Lederman 2004; Ward 2004; Morley-Fletcher 2003.

“…microcircuitry at the neurological level.”:
Leckman 2004; see Chapter 5, “The Mommy Brain.”

“…were measured in goat kids.”:
Roussel 2005.

“…important in the twenty-first century.”:
Campbell 2005.

“…in preserving harmonious relationships.”:
Knickmeyer 2005.

“…response instead of forging ahead.”:
Tannen 1990.

“…conflict, or displays of status.”:
Campbell 2005; Tannen 1990.

“…they typically don’t use it.”:
Tannen 1990.

“…is part of their makeup.”:
Maccoby 1998.

“…or commands given by girls.”:
Maccoby 1998.

“…more easily socially handicapped.”:
Baron-Cohen 2005.

“…emotional and social sensitivity.”:
Baron-Cohen 2005.

“…more estrogen than boys.”:
Grumbach 2005, personal communication.

“…every culture that’s been studied.”:
Maccoby 1987.

“…they’ll just stop playing.”:
Maccoby 1998.

“…involve any high-spirited boys.”:
Maccoby 1998, 2005 personal communication; Fagot 1985; Jacklin 1978.

“…nurturing or caregiving relationships.”:
Maccoby 1998.

“…of territory, and physical strength.”:
Maccoby 1998.

“…quality of their social relationships.”:
Knickmeyer 2005.

“…their usual interest in infants.”:
Wallen 2005.

“…play than do average females.”:
Wallen 1997, 2005; Goy 1988.

“…males than to those of females.”:
Berenbaum 1999.

“…dressing up in princess costumes.”:
Pasterski 2005; Hines 1994, 2004.