大脑中那些神经的连接构成亿万世界

So many things come down to connections -- especially the ones in your brain.
很多事情归根结底都是连接──尤其是你大脑中的那些神经。

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.
近来，有半打之多的研究着重探索了大脑接线图中的性别差异。这些研究表明，在神经纤维如何连接大脑各个区域方面，男性和女性显得截然不同。人脑中遍布着上万亿这样的关键连接，而遗传因素、人生经历和生物化学的相互影响、相互作用又塑造了这些连接的形成。

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.
目前尚不清楚，大脑连接中的性别差异可能会如何传导至人们的言行中──它们是否可能会影响一般男性与女性解读现实、处理信息、社交行为和形成判断的方式──但它们现在却引发了争议。

'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.
2011年，扎哈沙德与她在加州大学洛杉矶分校的同仁们进行了一项针对健康双胞胎的脑成像研究以追踪大脑中的连接情况，该研究共涉及147名女性和87名男性。她后来发现，在人脑额叶区中存在着“显著”的性别差异，该区域与自控力、决策力和演讲能力都息息相关。

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.
专家们称，只有将来自成百上千人的结果归纳结合起来看时，才会出现上述的神经模式。在任何某一个人身上，性别模式可能会被归为大脑结构和形态方面的个体差异，这些个体差异会使每个人都显得独一无二。

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.'
在饮食习惯、生活经历和生物化学的影响刺激下，神经元与突触从童年时期就开始被无情地修剪。这场筛选一阵一阵地继续，然后开始贯穿整个青春期。维尔马说：“童年时期，我们在男孩女孩身上看不到太多的差别。我们看到的大多数变化都发生在青春期。也就是那个时候，男女之间的大多数差别显现出来了。”

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.'
从广义上说，女性在20岁时左右脑之间的连接更多，而同龄的男性则是左、右脑各自内部的连接纤维更多。维尔马称：“女性大脑两个半球之间无论是从左至右、还是从右至左的连接都更好些。男性则是左、右脑各自内部的连接和后脑到前脑的连接更佳。”

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.
这就表明了女性可能在完成多重任务和分析思维方面更出色，而这需要左右脑之间的协作活动。反过来，男性可能在集中思维方面更为出色，这需要他们将注意力一次只放在一件事情上。但研究人员谨慎表示，这些结论都是推测性的，并非定论。

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.
专家们还警告称，连接方面微小的性别差异会被当成男女大脑尺寸及脑组织密度方面的正常差异而被摒弃。其他一些因素，如一个人是不是左撇子或右撇子，也会影响大脑结构。

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.
影响结果的还有：从这个实验室到下个实验室，这其中如何进行电脑运算。扎哈沙德说：“关于神经影像，有很多方式都能用来处理其相关数据，所以当你使用不同的方法处理数据还能得到相同的结果时，那简直不可思议。”