Hamann Stephan, Stevens Jennifer, Vick Janice Hassett, Bryk Kristina, Quigley Charmian A, Berenbaum Sheri A, Wallen Kim
Psychology Department, Emory University, Atlanta, GA, USA.
Psychology Department, Emory University, Atlanta, GA, USA.
Horm Behav. 2014 Nov;66(5):724-30. doi: 10.1016/j.yhbeh.2014.09.013. Epub 2014 Oct 2.
Androgens, estrogens, and sex chromosomes are the major influences guiding sex differences in brain development, yet their relative roles and importance remain unclear. Individuals with complete androgen insensitivity syndrome (CAIS) offer a unique opportunity to address these issues. Although women with CAIS have a Y chromosome, testes, and produce male-typical levels of androgens, they lack functional androgen receptors preventing responding to their androgens. Thus, they develop a female physical phenotype, are reared as girls, and develop into women. Because sexually differentiated brain development in primates is determined primarily by androgens, but may be affected by sex chromosome complement, it is currently unknown whether brain structure and function in women with CAIS is more like that of women or men. In the first functional neuroimaging study of (46,XY) women with CAIS, typical (46,XX) women, and typical (46, XY) men, we found that men showed greater amygdala activation to sexual images than did either typical women or women with CAIS. Typical women and women with CAIS had highly similar patterns of brain activation, indicating that a Y chromosome is insufficient for male-typical human brain responses. Because women with CAIS produce male-typical or elevated levels of testosterone which is aromatized to estradiol these results rule out aromatization of testosterone to estradiol as a determinate of sex differences in patterns of brain activation to sexual images. We cannot, however, rule out an effect of social experience on the brain responses of women with CAIS as all were raised as girls.
雄激素、雌激素和性染色体是引导大脑发育性别差异的主要因素，但其相对作用和重要性仍不明确。完全性雄激素不敏感综合征（CAIS）患者为解决这些问题提供了一个独特的机会。虽然患有CAIS的女性拥有Y染色体、睾丸，并产生男性典型水平的雄激素，但她们缺乏功能性雄激素受体，无法对自身的雄激素产生反应。因此，她们会发育出女性的身体表型，被当作女孩抚养，并成长为女性。由于灵长类动物的性别分化大脑发育主要由雄激素决定，但可能会受到性染色体组成的影响，目前尚不清楚患有CAIS的女性的大脑结构和功能更像女性还是男性。在对患有CAIS的（46,XY）女性、典型的（46,XX）女性和典型的（46,XY）男性进行的首次功能性神经影像学研究中，我们发现，与典型女性或患有CAIS的女性相比，男性在看到性图像时杏仁核的激活程度更高。典型女性和患有CAIS的女性的大脑激活模式高度相似，这表明Y染色体不足以引发男性典型的人类大脑反应。由于患有CAIS的女性会产生男性典型水平或升高水平的睾酮，而睾酮会被芳香化为雌二醇，这些结果排除了睾酮芳香化为雌二醇是大脑对性图像激活模式性别差异的决定因素。然而，我们不能排除社会经历对患有CAIS的女性大脑反应的影响，因为她们都是作为女孩抚养长大的。
