Striking similarities between the brains of gay men and straight women have been discovered by neuroscientists, offering fresh evidence that sexual orientation is hardwired into our neural circuitry. Scans reveal homosexual men and heterosexual women have symmetrical brains, with the right and left hemispheres almost exactly the same size. Conversely, lesbians and straight men have asymmetrical brains, with the right hemisphere significantly larger than the left.
Recent brain research has revealed structural differences in the hypothalamus in relation to biological sex and sexual orientation. Differences in size and cell number of various nuclei in the hypothalamus for homosexual versus heterosexual men have recently been reported in two studies. We have found that a cluster of cells in the preoptic area of the human hypothalamus contains about twice as many cells in young adult men as in women.
Swedish researchers have found that some physical attributes of the homosexual brain resemble those found in the opposite sex, according to an article published online June 16 in the Proceedings of the National Academy of Sciences. Other research has hinted that homosexuals may exhibit the tendencies of the opposite sex in brain behavior unrelated to sexual activity. Positron emission tomography PET scans taken by the researchers also show that in connectivity of the amygdala which is important for emotional learninglesbians resemble straight men, and gay men resemble straight women.
What makes people gay? Biologists may never get a complete answer to that question, but researchers in Sweden have found one more sign that the answer lies in the structure of the brain. Scientists at the Karolinska Institute studied brain scans of 90 gay and straight men and women, and found that the size of the two symmetrical halves of the brains of gay men more closely resembled those of straight women than they did straight men.
Researchers using brain scans have found new evidence that biology—and not environment—is at the core of sexual orientation. Scientists at the Stockholm Brain Institute in Sweden report in the Proceedings of the National Academy of Sciences USA that gay men and straight women share similar traits—most notably in the size of their brains and the activity of the amygdala—an area of the brain tied to emotion, anxiety and aggression. The same is true for heterosexual men and lesbians.
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For example, the brains of straight men and of gay women share certain common features: both are slightly asymmetric, with the right hemisphere larger than the left, say the Swedish researchers. On the other hand, the brains of gay men and straight women are both symmetrical. Similar trends emerged when scientists tracked connectivity in the amygdala, the region of the brain involved in emotional learning and in activating the fight-or-flight response.
The relationship between biology and sexual orientation is a subject of research. While scientists do not know what determines an individual's sexual orientationthey theorize that it is caused by a complex interplay of genetichormonaland environmental influences. Biological theories for explaining the causes of sexual orientation are favored by scientists.
Born this way? Chose this way? Activity, connectivity and structure of certain regions have been repeatedly shown to considerably differ between gay and straight people insert a snarky joke about bisexual erasure as well as cis- and transgenders.
The brains of homosexual men are structurally different from those of heterosexual men in a region thought to influence male sexual behavior, a scientist says he has found. The discovery, if confirmed, would be the first detection of a distinct pattern in the brain that could help explain sexual preference among men. In the new work, Dr.