Women's brains are different from men's 　

[1]Men and women show differences in behaviour because their brains are physically distinct organs, new research suggests. Male and female brains appear to be constructed from markedly different genetic blueprints.

[2]The differences in the circuitry1 that wires them up and the chemicals that transmit messages inside them are so great as to point to the conclusion that there is not just one kind of human brain, but two, according to recent neurological2 studies.

[3]Men may be from Mars and women may be from Venus, and since the American psychotherapist3 John Gray wrote his famous book, in 1992, on the idea, it has been a commonplace to think of men and women as being from different planets in terms of their emotional responses.

[4]But until recently, these differences were often explained by the action of adult sex hormones, or by social pressures that encouraged males and females to behave in a certain way.

[5]Increasingly, however, these assumptions are being challenged, according to a review of recent neurological research appearing in recent New Scientist magazine, and it is becoming clear that the brains of men and women show numerous anatomical4 differences.

[6]Some of these divergences, the review by Hannah Hoag suggests, could explain a number of mysteries, such as why men and women are prone to different mental health problems, why some drugs work well for one sex but have little effect on the other, and why chronic pain tends to affect women more than men.

[7]Although it has long been known that there were some male-female differences, it was thought they were confined to the hypothalamus5, the brain region involved in regulating food intake, fighting and the sex drive, among other things. But it is becoming clear that the relative sizes of many of the structures inside female brains are different from those of males.

[8]One study, by scientists at Harvard Medical School, found that parts of the frontal lobe6, which houses decision-making and problem-solving functions, were proportionally larger in women, as was the limbic cortex, which regulates emotions. Other studies have found that the hippocampus7, involved in short-term memory and spatial navigation, is also proportionally larger in women than in men – "perhaps surprisingly, given women's reputation as bad map readers" says the New Scientist review.

[9]Proportionally larger brain areas in men include the parietal cortex, which processes signals from the sensory organs and is involved in space perception, and the amygdala8, which controls emotions and social and sexual behaviour. "The mere fact that a structure is different in size suggests a difference in functional organisation," says Dr Larry Cahill of the Centre for the Neurobiology of Learning and Memory, at the University of California, Irvine.

[10]One area of research concerns the brain's pain-suppressing mechanisms, and points to the fact that they may be organised differently in men and women. This would explain why women can suffer long-term pain more, and why there can be sex differences in response to opium-derived painkilling drugs. The study notes: "Women get more relief from the opioid painkiller nalbuphine9 compared to men, whereas in men morphine is more effective and nalbuphine actually increases the pain intensity." It is possible these findings could lead to new painkillers being developed that are tailored to be more effective in women – but that is some way off10.

[11]Mental health is another area where real brain differences may offer explanations. Women are diagnosed with depression twice as often as men, and this may be linked to relative levels of the neurotransmitter serotonin. Boys, on the other hand, are more likely than girls to be diagnosed with autism, Tourette's syndrome11, dyslexia, attention-deficit disorder and early-onset schizophrenia. The review reports that Margaret McCarthy of the University of Maryland in Baltimore believes that hormone-like substances called prostaglandins, which help masculinise the male brain around the time of birth, may be partly to blame.

[12]One of the reasons why physiological differences between male and female brains have not been widely noted before may be that most of what we know about the brain comes from studies of males, animals and human volunteers.

[13]Professor Jeff Mogil from McGill University, in Montreal, Canada, who has demonstrated major differences in pain processing in males and females, puts it even more forcefully. He is astonished that so many researchers have failed to include female animals in their studies. "It's scandalous," he said. "Women are the most common pain sufferers, and yet our model for basic pain research is the male rat."

[1]最新研究表明，男女行为上表现出来的差异是因为他们的大脑是有着显著不同的器官。男性与女性大脑看来似乎建构于明显不同的基因蓝图。

[2]根据近期的神经学研究，连接他们大脑的脑电网络与在大脑内部传输信息的化学物质差异巨大从而使人们得出结论－并不只有一种人类大脑，而是两种。

[3]男人可能来自于火星，而女人则可能来自于金星。自从1992年美国心理治疗专家约翰?格雷在他所写的大名鼎鼎的著作中阐述了这一观点之后，从情感回应方面说来，认为男性和女性来自于不同的行星便已成为老生常谈之事。

[4]直到最近，这些不同还经常被解释为是由于成年人性激素的作用或是社会压力促使男性和女性按照某种既有的模式行事。

[5]然而根据《新科学家》杂志上刊登的一篇近期神经学研究回顾文章，这些假设正逐渐受到挑战。事实愈发清楚地表明男女大脑存在着诸多解剖差异。

[6]汉纳·霍格写的这篇回顾文章中指出这些差异中的一部分可用来解释大量谜团。例如，男性和女性为何倾向于产生不同的心理健康问题，为何某些药品对一种性别效果不错，而对另外一种性别却是收效甚微，为何慢性疼痛对女性的影响往往会多于男性。

[7]尽管男女有别早被人知，但此种认识只被局限于下丘脑——即专门用于调节食物摄取、争斗、性发育驱动的大脑区域。人们越来越清楚地认识到女性大脑中的许多构造的相对尺寸与男性的有所不同。

[8]从来自哈佛大学医学院的科学家们所进行的一项研究中发现女性大脑前额叶中具有决策和解决问题功能的那些部分从比例上说要比男性大，调节情感的皮质边缘也是如此。其它研究还发现，女性大脑中参与短时记忆和空间导向的海马区也要比男性的大些－或许令人惊讶，《新科学家》杂志中的回顾一文写到 “女性被称作糟糕的地图识别者” 。

[9]按比例来说，男性比女性大的大脑结构包括顶叶皮质（负责处理来自于感知器官的信号并参与空间感知）和杏仁体（用于控制情感以及社会行为和性行为）。加州大学尔湾分校学习与记忆神经生物学中心的拉里?卡西尔博士说，“一种结构在尺寸上的差异这一事实表明功能组织的不同。

[10]研究的一个领域涉及大脑的镇痛机制，这一研究指出如下事实，即男性和女性的镇痛机制组织不同。这些应该能解释女性更能承受常时间疼痛的原因以及为什么会有对鸦片类镇痛药物反应的性别差异。研究显示：“和男性比起来，女性可以从鸦片类镇痛药纳布芬中得到更多的缓解，但是对男性来说，吗啡对镇痛更有效而纳布芬却加重了疼痛。”这些发现可能导致开发出适用于女性更有效的新型止痛药剂，但那任重而道远。

[11]心理健康是真实的大脑差异可能提供解释的另一个研究领域。女性被诊断为抑郁症的数量是男性的二倍，这可能与神经传递介质血清素的相对水平有关。而另一方面男孩比女孩更易患自闭症、抽动症、失语症、注意力统合失调症以及早期攻击精神分裂症。这份回顾文章报告说在巴尔的摩马里兰大学的玛格丽特·麦卡锡相信那些被叫做前列腺素的在出生前后促进男性大脑雄性化的激素类物质是导致这些疾病的部分原因。

[12]之所以以前人们没有更多注意到男女大脑的生理差异，其中一个原因是我们所了解的绝大部分大脑知识都来自于对雄性动物及男性自愿者的研究。

[13]加拿大蒙特利尔麦卡吉尔大学的杰夫·摩泽尔教授已经演示了男女在疼痛感受上的主要差异，这使这项研究更有说服力。他很震惊，那么多的研究者在研究中没有包括雌性动物。他说：“这是可耻的。因为女性是最常见的疼痛承受者，而我们最基本的疼痛研究样本是雌性鼠。”