当我们想到大脑时，我们的第一个想法是灰质的：构成皮质的柔软的黄色灰色折叠组织。但是，看似无用的白质潜伏在下面，外观更坚硬，长长的树枝呢？还有更多的东西……

什么是白色的？

白质过去已经占据了后座。显然没有用，在对灰质进行探测和检查时，白质被忽略了。不久之后，白质就意识到了其在大脑中的重要作用。

But what iswhite matter? You could refer to it as the subway of the brain – connecting different regions of grey matter in the cerebrum to one another. Imagine living in a city and having to walk from one area to another 5 miles away; transport makes this much more fluent and helps make your tasks easier. This is pretty much the same for your brain!

白质很快。这要归功于电绝缘myelinsheaths (formed by glial cells) encasing each neuron’s process transmitting signals to other neurons. Nervous transmissionsare quick，含义灰质的区域可以连接并保持联系。有趣的是，这些髓鞘是使白色物质具有粉红色的颜色的原因。与地铁类似，白质大多在表面下方保持了许多链接和通道。

精神健康

Now imagine if the subway collapses or isn’t built properly – people from certain areas would have no access to these disconnected regions. The same can be said for the brain: except instead of people, we’re looking at information.

Regions of the brain need to communicate in order to carry out behaviour involved in everyday life. This isn’t just a human rule, it applies to animals too.

One example of this can be found in autism. Arecent study，使用扩散张量成像，分子自闭症identified white matter abnormalities in autism. Most importantly, it found that white matter tracts failed to reach long distances away from the cortex. In other words, this particular train didn’t travel too far.

自闭症中选定的道路重建。图像提供Billeci et al (2012)

但是不要忘记 - 白色物质也可以帮助我们获得更好地理解自闭症。通过查看这些“故障”的白质连接，我们可以了解更多有关自闭症的组件以及这些某些行为的起源的信息。

白质疾病

白质疾病还可以深入了解白质在大脑中的重要性。白质疾病靶向大脑中白质深处的小血管。反过来，这些微小的动脉然后被硬化，使营养素难以进入白质细胞。

直到最近，假定白质疾病仅损害了思维速度 - 但新的研究已经出现了，否则就却差不多。研究人员现在已经确定了与白质疾病相关的另外8个认知缺陷，表明该疾病患有对大脑的更广泛影响。The deficits range from language ability to delayed memory, and visuo-spatial construction.

白质疾病准确比首先想到的重量重，，，，causing real cognitive damage. It’s no surprise that the disease also contributes to vascular dementia or even Alzheimer’s.

Teens should get a railcard

We should really be cutting teens some slack. Adolescence is a tough time for most – but we often ignore the underlying reasons as to why. Youths are at a ‘关键时期’一生对神经发展至关重要，，，，和adverse obstacles may leave lasting effects on the brain. As we grow up, experiences will shape our brains. One thing we’ll all experience is stress(if not, then I guess you’re lucky!); you’d be surprised at themark stress makes在大脑，更重要的是白质。

Let’s look at the adolescent rhesus monkey and its relationship with its mother. In open access research from our生物学of Mood and Anxiety Disorders杂志，研究人员调查了父母虐待的长期影响on offspring. It’s a sad study with startling results. A boost in stress hormones most likely led to long-term effects on white matter. In turn, these structural changes in brain white matter were linked with social aggression, poor visual processing, and emotional regulation.

Rhesus monkeys. Image courtesy ofBrian Gratwicke

但是，情绪调节障碍到底意味着什么？在一个recent studyinBMC Psychiatry，研究人员看着青少年的白质。其中一些青少年被诊断出患有焦虑症，另一些则没有。人们发现患有情绪障碍的人在白质中具有结构异常 - 导致情绪调节问题，这导致了普通焦虑症。

Diffusion tensor imaging of white matter in teens with anxiety disorders. Image courtesy ofLiao et al (2014).

End of the line

We’ve come to the end of the blog – but hopefully it’s been an informative journey! The message to take home is that white matter research has a lot to teach us. And not all the messages are negative, nor are they final: white matter structures can change according to your environment, sometimes for the better. Just take a look at practising音乐家或者武术家呢