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更新时间:2013-12-24 13:40:57 来源:华尔街日报中文网 作者:佚名

Differences in How Men and Women Think Are Hard-Wired

So many things come down to connections -- especially the ones in your brain.


Women and men display distinctive differences in how nerve fibers connect various regions of their brains, according to a half-dozen recent studies that highlight gender variation in the brain's wiring diagram. There are trillions of these critical connections, and they are shaped by the interplay of heredity, experience and biochemistry.


No one knows how gender variations in brain wiring might translate into thought and behavior -- whether they might influence the way men and women generally perceive reality, process information, form judgments and behave socially -- but they are sparking controversy.


'It certainly is incendiary,' said Paul Thompson, a professor of neurology and director of the University of Southern California's Imaging Genetics Center. He is directing an effort to assemble a database of 26,000 brain scans from 20 countries to cross-check neuroimaging findings. 'People who look at findings about sex differences are excited or enraged,' he said.

南加州大学(University of Southern California)基因影像学中心(Imaging Genetics Center)负责人、神经学教授保罗·汤普森(Paul Thompson)说:“那肯定会点燃争议的导火索。”为了反复核对神经影像学的研究成果,汤普森正带头致力于组建一个数据库,该数据库将包含26,000份来自20个国家的脑部扫描资料。他说:“那些查看有关性别差异研究成果的人,有些兴奋不已,有些则忿怒填胸。”

Researchers are looking at the variations to explain the different ways men and women respond to health issues ranging from autism, which is more common among men, and multiple sclerosis, which is more common among women, to strokes, aging and depression. 'We have to find the differences first before we can try to understand them,' said Neda Jahanshad, a neurologist at USC who led the research while at the University of California, Los Angeles.

研究人员正在查看这些变化以解释男性和女性对健康问题的不同反应方式。这些问题包括从在男性中更常见的孤独症到女性中更常见的多发性硬化症、再到中风、衰老和抑郁症。南加州大学(USC)神经病学家妮达·扎哈沙德(Neda Jahanshad)在加州大学洛杉矶分校(the University of California, Los Angeles) 带领团队完成了上述研究,她说:“在我们试着弄清这些问题之前,我们得先找到它们的区别。”

Dr. Jahanshad and her UCLA collaborators conducted a 2011 brain-imaging study of healthy twins, including 147 women and 87 men, to trace connections in the brain. She discovered 'significant' sex differences in areas of the brain's frontal lobe, which is associated with self-control, speech and decision-making.


In the most comprehensive study so far, scientists led by biomedical analyst Ragini Verma at the University of Pennsylvania found the myriad connections between important parts of the brain developed differently in girls and boys as they grow, resulting in different patterns of brain connections among young women and young men.

在目前为止最全面的一项研究中,以宾夕法尼亚大学(the University of Pennsylvania)生物医学分析专家拉吉尼·维尔马(Ragini Verma)为首的科学家们发现,大脑重要部位之间的诸多连接随着男孩、女孩的成长而演化出差异,导致年轻女性和男性的脑内连接模式不同。

The team imaged the brains of 949 healthy young people, 521 females and 428 males, ranging in age from 8 to 22. Like Dr. Jahanshad's team, Dr. Verma employed a technique called Diffusion Tensor Imaging to trace how water molecules align along the brain's white-matter nerve fibers, which form the physical scaffolding of thought. The study was reported earlier this month in the journal the Proceedings of the National Academy of Sciences.

该团队对949名健康的年轻人进行了脑成像扫描,其中包括521名女性和428名男性,他们的年龄从8到22岁不等。同扎哈沙德的团队一样,维尔马也采用了一种名为“弥散张量成像(Diffusion Tensor Imaging)”的技术来追踪水分子是如何同脑白质神经纤维相应移动的,这形成了该想法的理论框架。这一研究于本月早些时候发表在《美国国家科学院院刊》(Proceedings of the National Academy of Sciences)上。

The neural patterns emerged only when combining results from hundreds of people, experts said. In any one person, gender patterns may be subsumed by the individual variations in brain shape and structure that help make every person unique.


Dr. Verma's maps of neural circuitry document the brain at moments when it is in a fury of creation. Starting in infancy, the brain normally produces neurons at a rate of half a million a minute, and reaches out to make connections two million times a second. By age 5, brain size on average has grown to about 90% of adult size. By age 20, the average brain is packed with about 109,000 miles of white matter tissue fibers, according to a 2003 Danish study reported in the Journal of Comparative Neurology.

在创造思潮难抑之时,维尔马的神经回路图会即时记录下大脑的情况。据2003年发表在《比较神经外科学杂志》(Journal of Comparative Neurology)上的一项丹麦研究表明,从婴儿时期开始,人脑通常就会以每分钟50万个的速度长出神经元,并以每秒钟200万次的速度伸展、形成连接。到了五岁的时候,大脑的尺寸一般会长到成年人脑的90%。到了20岁的时候,平均而言,大脑中会布满长达109,000英里(约合175,418千米)的白质组织纤维。

Spurred by the effects of diet, experience and biochemistry, neurons and synapses are ruthlessly pruned, starting in childhood. The winnowing continues in fits and starts throughout adolescence, then picks up again in middle age. 'In childhood, we did not see much difference' between male and female, Dr. Verma said. 'Most of the changes we see start happening in adolescence. That is when most of the male-female differences come about.'


Broadly speaking, women in their 20s had more connections between the two brain hemispheres while men of the same age had more connective fibers within each hemisphere. 'Women are mostly better connected left-to-right and right-to-left across the two brain hemispheres,' Dr. Verma said. 'Men are better connected within each hemisphere and from back-to-front.'


That suggests women might be better wired for multitasking and analytical thought, which require coordination of activity in both hemispheres. Men, in turn, may be better wired for more-focused tasks that require attention to one thing a time. But the researchers cautioned such conclusions are speculative.


Experts also cautioned that subtle gender differences in connections can be thrown off by normal disparities in brain size between men and women and in the density of brain tissue. Other factors, such as whether one is left- or right-handed, also affect brain structure.


Also affecting results are differences in how computer calculations are carried out from one lab to the next. 'With neuroimaging, there are so many ways to process the data that when you do process things differently and get the same result, it is fantastic,' Dr. Jahanshad said.