學(xué)者們通常認(rèn)為，女性在排卵期性欲會增強(qiáng),，在月經(jīng)期性欲會降低,。近日，北京大學(xué)醫(yī)學(xué)部胡佩誠教授等的研究卻得出了相反的結(jié)論：在女性最容易受孕的排卵期,，與性相關(guān)的神經(jīng)活動水平顯著下降,；而在月經(jīng)期，與性相關(guān)的神經(jīng)活動水平與平時無明顯差異,。該研究結(jié)果近日在線發(fā)表于《行為大腦研究》（Behav Brain Res）,。
據(jù)高嵩副教授介紹，女性對男性的心理反應(yīng)會受到月經(jīng)周期的影響,，以往多以問卷調(diào)查或訪談的方式來研究這一問題,，由于受試者主觀影響通常得出矛盾的結(jié)果。過去人們認(rèn)為,，在排卵期,，女性的性欲會增強(qiáng)，這樣可以增加受孕機(jī)會,，提高生育率,，有利于物種繁衍。
胡佩誠等應(yīng)用功能磁共振成像技術(shù),，觀察了15位女性在處理視覺性刺激時大腦的神經(jīng)反應(yīng),，研究了月經(jīng)周期對于女性大腦處理視覺性刺激的影響。研究發(fā)現(xiàn),，與預(yù)期不同,，在女性最容易受孕的排卵期，與性相關(guān)的神經(jīng)活動水平顯著下降,；而在月經(jīng)期,，與性相關(guān)的神經(jīng)活動水平與平時無明顯差別。
研究人員以性別對抗理論解釋了研究結(jié)果,，即女性在進(jìn)化過程中是“有意”地從生理和心理上隱藏其排卵期,，目的在于提升其從男性那里獲得的照料水平，并隱藏子代的血緣關(guān)系,，從而提高嬰兒的安全性,。這類隱藏排卵期的現(xiàn)象多見于由多個成年雄性和多個雌性組成群落的靈長目物種,；相反，在由1個成年雄性和多個雌性組成群落的物種,，如大猩猩和黑猩猩,，雌性有顯著的排卵標(biāo)志。另一種可能的解釋是妊娠會使女性付出巨大代價,，所以在受孕可能較大的排卵期,，女性會在完全不自覺的情況下變得更加慎重。（生物谷Bioon.com）
生物谷推薦原始出處：
Behavioural Brain Research doi:10.1016/j.bbr.2009.09.027
Brain activation evoked by erotic films varies with different menstrual phases: An fMRI study
Xun Zhua, Xiaoying Wangb, c, Carolyn Parkinsond, Chengxu Caie, Song Gaob, , and Peicheng Hua, ,
aDepartment of Medical Psychology, Peking University Health Science Center, No. 38, Xueyuan Road, Haidian District, Beijing 100191, China
bBeijing Key Lab of Medical Physics and Engineering, Peking University, Haidian Chengfulu 201, Beijing 100087, China
cDepartment of Radiology, Peking University First Hospital, No. 8, Xishiku Street, Xicheng District, Beijing 100034, China
dDepartment of Psychological and Brain Sciences, Dartmouth College, 6207 Moore Hall, Hanover, NH 03755, USA
eDepartment of Chemistry, Renmin University of China, No. 59, Zhongguancun street, Haidian district, Beijing 100872, China
In humans, fluctuating hormone levels throughout the menstrual cycle are believed to regulate many cyclical sexual behaviors and motivational processes. However, there is a dearth of research investigating the neural correlates of this phenomenon. We used functional magnetic resonance imaging to identify brain regions involved in sexual arousal's regulatory process. Fifteen female participants were scanned while viewing erotic film excerpts at three time points during a single menstrual cycle: ovulation, menstruation, and at one additional time point. Tripled two-group differences analysis revealed that significant activation in the comparison was observed in non-ovulatory phases of the menstrual cycle in parts of the right inferior frontal gyrus, right lateral occipital cortex, and left postcentral gyrus, as well as in the bilateral superior parietal lobule. Thus, our results indicate that brain activity differs in the ovulatory phase of the menstrual cycle compared to during other menstrual phases. This finding provides neurological evidence for the ovulatory cycle's modulation of the processing of the sexual arousal in female human brain.
