Path: utzoo!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!ora!ambar From: kim@mathcs.emory.edu (Kim Wallen {Psy}) Newsgroups: soc.feminism Subject: Re: physiological differences between male and female brains Message-ID: <7141@emory.mathcs.emory.edu> Date: 13 Mar 91 11:28:25 GMT References: <1991Feb22.215346.8448@aero.org> Sender: ambar@ora.com (Jean Marie Diaz) Organization: Emory University, Dept of Math and CS Lines: 36 Approved: ambar@ora.com In article yoda!jls@igor.rational.com (Jim Showalter) writes: >Regarding physiological differences between male/female brains, this >turns out to be largely bogus. There seemed to be some VERY minor >structural differences, but the sample size was quite small and there >has yet to be independent corroboration. Jim's comment is relatively accurate in reagrd to Callosal differences in males and females (this difference is not clearly resolved), but it is distinctly incorrect in regard to hypothalamic differences. There is a very clear difference in certain hypothalmic nuclei in male and female humans which develops between 4-6 years of age and continues through adulthood. [reference: Swaab, DF &Hofman, MA 1988 Sexual differentiation of the human hypothalamus: Ontogeny of the sexually dimorphic nucleus of the preoptic area. Developmental Brain Research 44:314-8.] This neural difference is analogous to those reported in rats, guinea pigs, ferrets, and monkeys. It seems this area (which is larger in females than males) is involved in suppressing female sexual behavior in males. When it is lesioned in male rats they now readily show female-like sexual receptivity and initiation. Interestingly in the human study three transsexual males (male to female) all had sexually dimorphic nuclei in the female, but not the male range. Kim Wallen Psychology Department Emory University Atlanta, GA 30322 (404) 727-4125 INTERNET: kim@unix.cc.emory.edu UUCP: {gatech decvax}!emory!kim BITNET: kim@emoryu1