Navigation Links
Gay Men, Straight Women Have Similar Brains

Scans also showed similarities between lesbians, straight men

MONDAY, June 16 (HealthDay News) - MRI and PET scan studies are showing remarkable similarities between the brains of gay men and straight women, and between those of lesbians and straight men.

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. They noted strong similarities between gay men and straight women, and lesbians and straight men.

The findings are published in the current issue of the Proceedings of the National Academy of Sciences.

"This is a very interesting study demonstrating a possible neurobiological relationship in brain size between gay men and straight women," said Paul Sanberg, distinguished professor of neurosurgery and director of the University of South Florida Center for Aging and Brain Repair in Tampa.

The neurobiology of sexual orientation is a controversial topic. Some research suggests that the brain activity of homosexual individuals in areas unrelated to sex mirror brain activity in straight individuals of the opposite sex. And certain psychological studies have revealed differences in how men and women use the brain's different hemispheres for verbal tasks, for example.

For this study, researchers from the Karolinska Institute in Stockholm first performed magnetic resonance imaging (MRI) on 90 participants -- 25 heterosexual men and an equal number of heterosexual women, plus 20 homosexual men and 20 homosexual women.

The right hemispheres of straight men and gay women were found to be bigger than the left, while the respective volume of these two cerebral hemispheres were about the same in gay men and straight women.

Fifty of the original participants also underwent positron emission tomography (PET) measurements of blood flow to the brain, designed to analyze connections between the right and left amygdalas. PET scans were performed both while the participants were resting and while they were smelling unscented air.

Here again, lesbians appeared to react more like straight men, while gay men were more like straight women.

According to the authors, fight-or-flight reactions -- controlled in part by the amygdala -- are more common in men than in women.

The differences, which were not related to sexual attraction, could be due to environmental effects, genetics or the influence of sex hormones, the study authors stated.

Although some sex differences in brain size are visible at birth, the brain continues to develop as the child matures, meaning that environmental factors could also play a role.

The current wisdom regarding genetics and sexual orientation posits that genes may play a role in male homosexuality but not in female homosexuality, the researchers said.

Experts have also speculated that exposure to sex hormones prenatally influence sexual preference. Male rhesus monkeys have more androgen (a male sex hormone) receptors in the right side of the brain, while females have an equal distribution of receptors for the hormone.

And brain asymmetry in male rats is established by early exposure to androgens. Symmetry in female brain hemispheres can be reversed by removing the ovaries soon after birth.

This study does little to clarify the reasons behind the differences, the researchers added, although it certainly does add to the debate.

More information

There's more on how the brain works at The Franklin Institute.

SOURCES: Paul Sanberg, Ph.D., D.Sc., distinguished professor of neurosurgery and director, University of South Florida Center for Aging and Brain Repair, Tampa; Proceedings of the National Academy of Sciences, June 16-20, 2008

Copyright©2008 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. PartsSource Given 2008 Leading Edge Award for Second Straight Year
2. OPEN LETTER: Medical Journal Calls Upon Barack Obama to Set the Record Straight on AIDS Virus
3. The pitter patter of little feet... climbing straight up a wall
4. Homeless Vets - VA Sets the Record Straight
5. HIV/AIDS Cases Among State and Federal Prison Inmates Fell for the Sixth Straight Year During 2005
6. Different HIV rates among gay men and straight people not fully explained by sexual behavior
7. Health Insurance Premium Growth Slows for Fourth Straight Year
8. Less Intensive Treatment Given Diabetic Women With Heart Disease
9. Women Get Lung Cancer From Smoking at Same Rates as Men
10. Trust for Americas Health Releases Report on Connection between Womens Health and Stalled Infant Mortality Rates
11. Ovarian function and fertility preserved in women with severe systemic lupus erythematosus
Post Your Comments:
Related Image:
Gay Men, Straight Women Have Similar Brains
(Date:10/13/2015)... (PRWEB) , ... October 13, 2015 , ... ... workflow solutions, announced today their sponsorship of the Microsoft Dynamics AXUG, GPUG and ... AXUG Summit, GPUG Summit and NAVUG Summit are independent user conferences designed and ...
(Date:10/13/2015)... ... October 13, 2015 , ... In an age where ... were 36 percent lower per square foot than in 2009. The Williamsport Regional Medical ... heating and cooling has decreased by eight percent. , According to Facilities Management ...
(Date:10/13/2015)... ... October 13, 2015 , ... e-con Systems Inc., a leading embedded ... See3CAM_CU40, the industry’s first RGB-IR pixel format camera with a USB 3.0 interface ... e-con’s See3CAM family of UVC USB 3.0 cameras, is based on the 1/3-inch OV4682 ...
(Date:10/13/2015)... Los Angeles, CA (PRWEB) , ... October 13, ... ... has published an in-depth review of Anik Singal's newly launched "Publish Academy" ... scaling a digital publishing business opened for enrollment today, and marketers around the ...
(Date:10/13/2015)... , ... October 13, 2015 ... ... Omega-3, a first-of-its kind product that targets the unique health needs of ... of the American Pregnancy Association ( ), utilizes Nordic Naturals’ exclusive, ...
Breaking Medicine News(10 mins):
(Date:10/13/2015)... , Oct. 13, 2015  Yesterday Congresswoman ... Vaccines Holly Springs manufacturing site located in ... the facility has produced Flucelvax ® (Influenza Vaccine) using ... potential for faster start-up and is not reliant on ... Limited acquired the influenza vaccines business of Novartis AG ...
(Date:10/12/2015)... 13, 2015 the United States ... a non-clinical capacity. --> the United States ... a non-clinical capacity. --> The University of Texas MD ... the first high field (1.5 Tesla) MRI-guided linear accelerator in ... system will be operating in a non-clinical capacity. Royal ...
(Date:10/12/2015)... , Oct. 12, 2015  Former White House Spokesman, and ... for the House Narcotics Committee, Robert Weiner , and ... Policy." The two emphasize that this is now a potential ... to Jeb Bush , Carly Fiorina to ... the newest federal statistics, which they call "a shocker: 23 ...
Breaking Medicine Technology: