Investigations into the neural underpinnings and biological correlates of asexuality

几乎没有关于人类无性行为的研究，无性行为被定义为“性吸引力的缺乏”。虽然从表面上看，无性恋研究似乎是一个非常具体的研究领域，但无性恋的特殊性质可能为研究大脑、认知和行为的性别分化提供了一个独特的人类模型。因此，无性恋可能是打开我们对所有性行为(典型的和非典型的)理解的钥匙。*我实验室的十年研究检验了无性恋是一种独特的性取向这一信条。具体地说，我已经排除了无性恋是性功能障碍、心理障碍和偏执的理论。此外，我的工作表明，终生缺乏性吸引力可能是一种与生俱来的生物学特征。性吸引力是无性恋的关键。一般说来，荷尔蒙、遗传和免疫过程被认为会影响大脑的性别分化，并导致性吸引力和性取向的变化，无性恋似乎也是如此。在这里，我们建议进一步探讨这一点。*在5年的时间里，我们提出了3项研究，每项研究都采用了以前不适用于无性恋的性取向研究的有效方法。在研究1中，我们将使用性吸引的自动测量(观看视觉刺激时的眼球运动和瞳孔扩大)来评估对性偏好和非偏好线索的视觉注意和认知加工。*在研究2中，我们将使用一系列神经成像技术对比无性和有性群体(包括性欲过敏者和对照组)，以研究包括大脑结构和功能在内的神经解剖特征。这将是第一次对无性恋者进行神经成像研究。当参与者休息和观看色情刺激时，大脑活动将在90分钟的大脑扫描过程中被记录下来。*研究3将通过调查身体生长模式，例如身高、指长比和利手，重复和扩展我早期对无性恋生物标记的研究。这些变量被认为是性取向发展变化的生物标志(特别是在同性恋参与者中)，并被认为反映了雄激素对产前的影响。我们还将通过调查无性个体的亲生兄弟姐妹的数量和性别是否与有性个体的亲生兄弟姐妹的数量和性别有显著差异，来调查兄弟姐妹出生顺序效应，这是性取向的另一个生物标志。总体而言，拟议的研究计划将直接回答有关无性恋的神经相关性的令人困惑的问题，并将完善我们关于无性恋和其他性取向发展的病因路径的概念模型。它将改变我们对大脑、认知和行为性别分化的理解。

Very little research exists on human asexuality, defined as “absence of sexual attraction.” While asexuality research seems on the surface to be a very specific field of research, the exceptional nature of asexuality may provide a unique human model for studying sexual differentiation of the brain, cognition, and behaviour. Thus, asexuality may be the key that unlocks our understanding of all the sexualities (typical and atypical).******A decade of research in my lab has tested the tenet that asexuality is a unique sexual orientation. Specifically, I have ruled out theories that asexuality is a sexual dysfunction, a psychological disorder, and a paraphilia. Furthermore, my work suggests that the lifelong lack of sexual attraction, essential to asexuality, may be an innate biological characteristic. In general, hormonal, genetic, and immunological processes have been hypothesized to influence sexual differentiation of the brain and to lead to variations in sexual attraction and orientation, and this seems also to be the case in asexuality. Here, we propose to probe this further.******Over 5 years we propose 3 studies, each employing validated methodologies in sexual orientation research not previously applied to asexuality. In Study 1, we will use automatic measures of sexual attraction (eye-movements and pupil dilations while viewing visual stimuli) to assess visual attention to and cognitive processing of sexually preferred and non-preferred cues. ******In Study 2, will we use a series of neuroimaging techniques to contrast asexual and sexual groups (including hypersexual and control participants) to investigate neuroanatomic features including brain structure and function. This will be the first-ever study of neuroimaging in asexuals. Brain activity will be recorded in a 90-min brain scanning session, while participants are at rest and while they are viewing erotic stimuli. ******Study 3 will replicate and expand my earlier study of biological markers of asexuality by investigating physical growth patterns; e.g., height, finger-length ratio, and handedness. These variables are considered biomarkers of variations in sexual orientation development (specifically among gay participants) and are thought to reflect prenatal influence of androgens. We will also investigate the fraternal birth order effect, another biomarker of sexual orientation, by investigating whether the number and sex of biological siblings of asexual individuals significantly differs from that of sexual individuals. ******Overall, the proposed research program will directly answer puzzling questions about the neural correlates of asexuality, and will refine our conceptual models of etiological pathways of the development of asexuality as well as other sexual orientations. It will transform our understanding of the sexual differentiation of the brain, cognition, and behaviour.