Human Sexuality Studies at Stanford University. INAH3 research Researchers had been comparing the brains of men and women since the 1980s, but the article that caught LeVay's attention was published by a group at UCLA. In the study, the researchers compared the hypothalami of 11 men to 11 women. Of particular interest to LeVay was an area the researchers called the "Interstitial Nucleus of the Anterior Hypothalamus" (INAH3), a part of the brain that had been found to help regulate sexual behavior. The UCLA team found that INAH3 was, on average, twice as large in men as it was in women. This made LeVay wonder if he would see differences in this grouping of cells based on sexual orientation as well. "I was already working on structure and function in one part of the brain, so working on the sexual part of the brain wasn't a big switch." Over a period of nine months, LeVay performed surgery on the brains of 41 cadavers: 18 gay men (plus 1 bisexual male), 16 straight men, and 6 straight women. To ensure that the process was fully blinded, he'd had each brain numerically encoded to conceal the sexual orientations of each donor. In 1991, LeVay published "A difference in hypothalamic structure between heterosexual and homosexual men" in Science. On average, LeVay found that the INAH3 in the brains of heterosexual men were more than twice as large as that found in the homosexuals. In fact, the INAH3 size of the homosexual group was the same size as the women. LeVay wrote that "This finding indicates that INAH is dimorphic with sexual orientation, at least in men, and suggests that sexual orientation has a biological substrate." This was the first scientific study that looked specifically at differences between brains on the basis of sexual orientation. Because of this, LeVay's finding attracted a lot of media attention. The study results were featured on PBS, Newsweek, Nightline, Donahue, and The Oprah Winfrey Show. The results received push back from some religious groups as well as from members of the LGBT community. There were also several criticisms from scientists: The AIDS virus can attack the central nervous system, and nearly all of the gay men in LeVay's study had died of AIDS. What effect, if any, did HIV have on this region of the brain? Were the perceived differences the result of biology or because of HIV's