How the male brain works

Added: Chauntae Donald - Date: 22.01.2022 18:33 - Views: 36972 - Clicks: 2160

But he did have a good reason. So, he zeroed in on sex-associated behavioral differences in mating, parenting and aggression. His plan was to learn what he could about the activity of genes tied to behaviors that differ between the sexes, then use that knowledge to help identify the neuronal circuits — clusters of nerve cells in close communication with one another — underlying those behaviors. At the time, this was not a universally popular idea. The neuroscience community had largely considered any observed sex-associated differences in cognition and behavior in humans to be due to the effects of cultural influences.

Animal researchers, for their part, seldom even bothered to use female rodents in their experiments, figuring that the cyclical variations in their reproductive hormones would introduce confounding variability into the search for fundamental neurological insights. Not how well they work, mind you. Nirao Shah studies how some genes at work in the mouse brain determine sex-specific behaviors, like the female trait of protecting the nest from intruders. He says most of these genes have human analogues but their function is not fully understood.

Photograph by Lenny Gonzalez. Injust a few years before Shah launched his sex-differences research, Diane Halpern, PhD, past president of the American Psychological Association, began writing the first edition of her acclaimed academic text, Sex Differences in Cognitive Abilities. Social psychologists and sociologists pooh-poohed the notion of any fundamental cognitive differences between male and female humans, notes Halpern, a professor emerita of psychology at Claremont McKenna College.

After reviewing a pile of journal articles that stood several feet high and numerous books and book chapters that dwarfed the stack of journal articles … I changed my mind. There was too much data pointing to the biological basis of sex-based cognitive differences to ignore, Halpern says. For one thing, the animal-research findings resonated with sex-based differences ascribed to people. These findings continue to accrue. In a study of 34 rhesus monkeys, for example, males strongly preferred toys with wheels over plush toys, whereas females found plush toys likable.

Halpern and others have cataloged plenty of human behavioral differences. Women excel in several measures of verbal ability — pretty much all of them, except for verbal analogies. Men, on average, can more easily juggle items in working memory. Many of these cognitive differences appear quite early in life.

Infant girls respond more readily to faces and begin talking earlier. Boys react earlier in infancy to experimentally induced perceptual discrepancies in their visual environment. In adulthood, women remain more oriented to faces, men to things. All these measured differences are averages derived from pooling widely varying individual. While statistically ificant, the differences tend not to be gigantic.

They are most noticeable at the extremes of a bell curve, rather than in the middle, where most people cluster. Some argue that How the male brain works may safely ignore them. Women are twice as likely as men to experience clinical depression in their lifetimes; likewise for post-traumatic stress disorder. Men are twice as likely to become alcoholic or drug-dependent, and 40 percent more likely to develop schizophrenia.

The neuroscience literature shows that the human brain is a sex-typed organ with distinct anatomical differences in neural structures and accompanying physiological differences in function, says UC-Irvine professor of neurobiology and behavior Larry Cahill, PhD. Brain-imaging studies indicate that these differences extend well beyond the strictly reproductive domain, Cahill says.

InCahill scanned the brains of men and women viewing either highly aversive films or emotionally neutral ones. The aversive films were expected to trip off strong negative emotions and concomitant imprinting in the amygdala, an almond-shaped structure found in each brain hemisphere. But in women, this relationship was observed only in the left amygdala. In men, it was only in the right amygdala. Cahill and others have since confirmed these. They recall emotional memories more quickly, and the ones they recall are richer and more intense.

Numerous studies show that they do, sometimes with medically meaningful implications. A study in JAMA Psychiatry imaged the brains of 98 individuals ages 8 to 22 with autism spectrum disorder and 98 control subjects. Both groups contained roughly equal s of male and female subjects. But the great majority of female subjects with ASD, the researchers found, had cortical-thickness variation profiles similar to those of typical non-ASD males. One big reason is that, for much of their lifetimes, women and men have different fuel additives running through their tanks: the sex-steroid hormones.

In female mammals, the primary additives are How the male brain works few members of the set of molecules called estrogens, along with another molecule called progesterone; and in males, testosterone and a few look-alikes collectively deemed androgens. Importantly, males developing normally in utero get hit with a big mid-gestation surge of testosterone, permanently shaping not only their body parts and proportions but also their brains. In general, brain regions that differ in size between men and women such as the amygdala and the hippocampus tend to contain especially high concentrations of receptors for sex hormones.

Another key variable in the composition How the male brain works men versus women stems from the sex chromosomes, which form one of the 23 pairs of human chromosomes in each cell. Generally, females have two X chromosomes in their pair, while males have one X and one Y chromosome. A gene on the Y chromosome is responsible for the cascade of developmental events that cause bodies and brains to take on male characteristics.

Some other genes on the Y chromosome may be involved in brain physiology and cognition. Scientists routinely acknowledge that the presence or absence of a single DNA base pair can make a medically important difference. What about an entire chromosome? They tried it with one of their candidate genes, turning off one that was normally more active in females. All this points to a picture of at least parts of the brain as consisting of modules. Each module consists of a neural or genetic pathway in charge of one piece of a complicated behavior, and responds to genetic and hormonal als.

These modules — or at least some of them — are masculinized or feminized, respectively, by the early testosterone rush or its absence. The mammalian brain features myriad modules of this sort, giving rise to complex combinations of behavioral traits. Consider the genes Shah has isolated whose activity levels differ ificantly in the brains of male and female mice.

But when we looked at publicly available databases to find out what we do know about them, we found a surprising that in humans have been linked with autism, alcoholism and other conditions. The role of biology is not zero. Bruce Goldman is a science writer in the Office of Communications. him at goldmanb stanford. Two minds. The cognitive differences between men and women. Behavior differences Injust a few years before Shah launched his sex-differences research, Diane Halpern, PhD, past president of the American Psychological Association, began writing the first edition of her acclaimed academic text, Sex Differences in Cognitive Abilities.

How our brains differ The neuroscience literature shows that the human brain is a sex-typed organ with distinct anatomical differences in neural structures and accompanying physiological differences in function, says UC-Irvine professor of neurobiology and behavior Larry Cahill, PhD. Additional Reading. A new rhythm Dance benefits Parkinson's patients. His dear Watson A doctor and his Chihuahua make explaining narcolepsy look elementary On the button Treatments that work for people just like you Leaving frailty behind A conversation with Laura Hillenbrand.

How the male brain works

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