Department of Women's and Children's Health, and Neurology Clinic, Karolinska Institutet and Hospital, Stickholm, SE-171 76, Sweden.
Hum Brain Mapp. 2018 Mar;39(3):1175-1186. doi: 10.1002/hbm.23908. Epub 2017 Dec 11.
The neurobiology of sexual orientation is frequently discussed in terms of cerebral sex dimorphism (defining both functional and structural sex differences). Yet, the information about possible cerebral differences between sex-matched homo and heterosexual persons is limited, particularly among women. In this multimodal MRI study, we addressed these issues by investigating possible cerebral differences between homo and heterosexual persons, and by asking whether there is any sex difference in this aspect. Measurements of cortical thickness (Cth), subcortical volumes, and functional and structural resting-state connections among 40 heterosexual males (HeM) and 40 heterosexual females (HeF) were compared with those of 30 homosexual males (HoM) and 30 homosexual females (HoF). Congruent with previous reports, sex differences were detected in heterosexual controls with regard to fractional anisotropy (FA), Cth, and several subcortical volumes. Homosexual groups did not display any sex differences in FA values. Furthermore, their functional connectivity was significantly less pronounced in the mesial prefrontal and precuneus regions. In these two particular regions, HoM also displayed thicker cerebral cortex than other groups, whereas HoF did not differ from HeF. In addition, in HoM the parietal Cth showed "sex-reversed" values, not observed in HoF. Homosexual orientation seems associated with a less pronounced sexual differentiation of white matter tracts and a less pronounced functional connectivity of the self-referential networks compared to heterosexual orientation. Analyses of Cth suggest that male and female homosexuality are not simple analogues of each other and that differences from heterosexual controls are more pronounced in HoM.
性取向的神经生物学经常被讨论为大脑性别二态性（定义了功能和结构上的性别差异）。然而，关于性别匹配的同性恋和异性恋者之间可能存在的大脑差异的信息是有限的，特别是在女性中。在这项多模态 MRI 研究中，我们通过研究同性恋和异性恋者之间可能存在的大脑差异，并询问在这方面是否存在任何性别差异，来解决这些问题。我们比较了 40 名异性恋男性（HeM）和 40 名异性恋女性（HeF）、30 名同性恋男性（HoM）和 30 名同性恋女性（HoF）的皮质厚度（Cth）、皮质下体积以及功能和结构静息状态连接的测量值。与之前的报告一致，在异性恋对照组中，存在性别差异的方面包括各向异性分数（FA）、Cth 和几个皮质下体积。同性恋群体在 FA 值方面没有显示出任何性别差异。此外，他们的功能连接在中前额叶和楔前叶区域显著不明显。在这两个特定区域，HoM 的大脑皮层也比其他群体更厚，而 HoF 与 HeF 没有差异。此外，在 HoM 中，顶叶的 Cth 显示出“性别反转”的值，在 HoF 中没有观察到。与异性恋倾向相比，同性恋倾向与白质束的性别分化不明显和自我参照网络的功能连接不明显有关。Cth 的分析表明，男性和女性同性恋并不是彼此的简单类似物，与异性恋对照组的差异在 HoM 中更为明显。
