We are what we think and how we think.
That much scientists now understand. More elusive is charting the precise workings of the brain that produce an individual's perception, intellect and emotion. Even more obscure are the cerebral origins of gender behavior and gender-based differences in brain function. For example, whether or not differences in cognitive ability are learned behaviors or the consequence of differences in brain anatomy and molecular biology between the sexes is difficult to establish.

The Brain
Discovering how each gender thinks, acts and feels

Understanding the original super computer--the brain--is proving a difficult task even for the species within which it operates.

What Do We Know About How the Sexes Act and Think?
Other Known Differences Between Male and Female Brains
Gender and Learning Disabilities
Attention Deficit Hyperactivity Disorder

What Do We Know About How the Sexes Act and Think?

The most obvious, and in some instances, the most blatant examples of gender differences in how we think and act involve mating behaviors. Mammals, including humans, have gender-based differences in mating behavior that are the result of hardwired brain functions and not social training. The courtship rituals of the elephant or the ground hog are clearly gender-based programs fueled by inherent differences in the sexes’ brain. Although these animals have highly evolved social structures, when the male and female display their gender-distinct mating rituals they are not acting out cultural imperatives but biochemical mandates.

Not all mammals' courtship behaviors are so obviously a product of brain-function differences between the sexes, however. In humans, these more subtle behaviors bear witness to the surprisingly abundant gender-specific differences in the central nervous system (CNS). For example, in men the auditory brainstem response has a longer latency period and smaller amplitude than in women. This may have a profound effect on men's response to auditory stimuli. Other differences in sexual behavior may be indicated by structural distinctions between male and female brains. In the areas of the brain that influence sexual behavior, women are reported to have more gray matter than men in a language-related cortical region, but not in a more visuospatially related cortical region. This indicates that the sexes have structural differences in the cerebral cortex. It also raises the question, are men inherently more responsive to visual sexual stimulation than women and are women intrinsically more responsive to sexual wooing through words?

Source: Schlaepfer TE; Harris GJ; Tien AY; Peng L; Lee S; Pearlson GD; Structural differences in the cerebral cortex of healthy female and male subjects: a magnetic resonance imaging study; Psychiatry Res, 61(3):129-35 1995 Sep 29.

Other Known Differences Between Male and Female Brains

Although not directly related to mating behavior, the ways men's and women's brains move information across the brain synapses may also be gender-determined. Gender-specific differences in both the anatomy and in the chemistry of neural transmission in the CNS appear early in fetal life and are, in large part, due to the organizing action of hormones secreted by the gonads, thyroid and adrenal glands on the developing brain. It is possible that neurological diseases (chorea minor, migraine headaches) and psychiatric diseases (depression) that are more common in one sex (women in these three examples) are actually the consequences of neurodevelopmental errors.
Legato: Gender-Specific Aspects of Human Biology for the Practicing Physician (GSAHB), Futura Publishing Co., 1997; p. 19-23.

In a part of the temporal lobe associated with language skills, women's brains contain up to 11% more brain cells than men's brains. This does not necessarily mean that women are smarter than men, but it does show they are different.
Mark Nichols; Boys, Girls and Brain Power-the research of Sandra Witelson, McMaster University; Maclean's, 1/22/96.

Males are faster at solving problems involving some types of spatial perceptions than are women.
GSAHB p 19-20

Male brain neurons are about a third larger than female neurons; male and female neurons take up significantly different amounts of dopamine--a brain chemical that acts as a mood enhancer, relieves pain and regulates motion.
GSAHB p 25

Portions of the left brain hemisphere are more prominent in males. Some investigators correlate this with a reported greater hemispheric specialization at earlier ages in males and the lower incidence in females of developmental disorders associated with language deficits--known to be associated with the left hemisphere.
GSAHB p 23

Estrogen replacement therapy is associated with a 40% lower incidence of Alzheimer's disease. This disorder is twice as prevalent in women as in men, a difference in frequency not found in other forms of dementia.
GSAHB p 22

Women are two to three time more likely to experience depression than are men. The gender difference emerges around the age of 15. Depression may not be as gender-linked as commonly thought, however. Over the past decades the prevalence of depression has become more equal among the sexes. This may be because depression is caused by more than gender-specific physical attributes: It involves an interaction between genetic, hormonal and environmental factors.
GSAHB p 23-24

There appears to be significant sex differences in aging of brain areas that are essential to higher cognitive functioning. This may explain some of the age-sex differences in human cognition and response to brain injury and disease.

Age-related loss of brain volume is significantly greater in men than women in whole brain and frontal and temporal lobes, whereas it is greater in women than men in hippocampus and parietal lobes.

Significant sex differences exist in the effect of age on regional brain metabolism, and asymmetry of metabolism, in the temporal and parietal lobes, Broca's area, thalamus, and hippocampus.

Sources: Azari NP, Pettigrew KD, Pietrini P, Murphy DG, Horwitz B, Schapiro MB; Sex differences in patterns of hemispheric cerebral metabolism: a multiple regression/discriminant analysis of positron emission tomographic data; Int J Neurosci 1995;81:1-20. Murphy DGM, DeCarli C, McIntosh AR, Daley E, Szczepanik J, Schapiro MB, Rapoport SI, Horwitz B.; Sex differences in human brain aging: an in vivo volumetric MRI and PET study; Arch Gen Psychiatry 1996;5317:585-594.

Gender and Learning Disabilities

Boys and men are thought to be more likely to suffer from various learning disabilities more often than girls. Some researchers propose psychosocial causes; others look to brain chemistry and/or to hormones. There are those who cast doubt on the premise altogether: They suggest that the alleged preponderance of learning disabilities in men (ranging from 3:1 to 15:1) may be, in part, a result of gender-biased research. Most of the work done on learning disabilities concentrates on boys and men.
GSAHB p 20

Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is the most thoroughly studied of all childhood brain disorders. Nonetheless, because so few girls or women have been looked at there is a risk of false negatives in sex comparisons—and real and important sex-linked differences in diagnosis and treatment may be overlooked in girls. For example:

The teenage pregnancy rate among girls with ADHD is higher than in non-ADHD girls.
Girls with ADHD have a higher rate of first-degree relatives with ADHD than do boys with ADHD.

Sex differences in ADHD, L. Eugene Arnold, Journal of Abnormal Child Psychology, Oct 1996