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【bio-news】老年痴呆症及自闭症与神经纤维长短之
人类大脑活动也许是目前科学最难以解释的生物现象之一。我们虽然可以形象模拟种种神经细胞活动的过程，但基本上没人可以肯定这个错综复杂的网络系统的运作模式。值得肯定的是，神经元或通过郎飞结或通过局部电流传递神经冲动。那么神经元突触之长短会否影像大脑信息传递的速度，长短神经纤维的通路结构与诸如老年痴呆症，自闭症之类的脑部疾病是否有关呢？详见下文。
原文：
New Insights Into Brain Organization Provided By Study
Main Category: Neurology / Neuroscience News
Article Date: 05 Aug 2006 - 2:00am (PDT)
Scientists have provided new insights into how and why the brain is organised - knowledge which could eventually inform diagnosis of and treatments for conditions like Alzheimer's disease and autism.
A study by Newcastle University, UK, and the International University Bremen, Germany, debunked a prevailing theory that the nervous system should have mainly very short nerve fibre connections between nerve cells, or neurons, to function at its most effective.
Instead the study, which carried out a sophisticated computer analysis of public databases containing detailed information of worldwide anatomical studies on primate and worm brains, found that long nerve fibre connections were just as vital to overall brain function as short ones.
Much of what we know about the human brain derives from neuroscience research on primates, which are used because they have have experienced similar evolutionary stages to humans.
Brain scans of Alzheimer's patients and people with autism have shown that they are lacking certain long-distance neural interactions, although experts have yet to discover their specific purpose.
The new study, published in the academic journal PLoS Computational Biology, found that long fibres are important because they can send messages quickly over a longer distance compared with if the same message was sent over the same distance via lots of short fibres. It also found that long fibres are more reliable for transmission of messages over longer distances.
"You can draw parallels with a train journey from Newcastle to London," said lead researcher, Dr Marcus Kaiser, of Newcastle University's School of Computing Science and the University's Institute of Neuroscience.
"For example, you would get to London much more quickly and easily if you took a direct train there. However, if you had to make the journey via Durham, Leeds and Stevenage, changing trains each time, then it will take you longer to get there, and there is the possibility you would miss a connection at some point. It's the same in the human brain."
The computer programme, run over several days, took information about the length of nerve fibres in the primate brain and neuronal connections called axons in the brain of a species of worm known as Caenorhabditis elegans. It then tested if the total length of fibres could be reduced, by testing billions of different position arrangements. Indeed, wiring lengths could be reduced by up to 50% owing to the fact that neural systems have surprisingly many long-distance connections.
Co-researcher Dr Claus Hilgetag, an associate professor with International University Bremen's School of Engineering and Science, said: "Many people have suggested that the brain is like a computer and that for optimum effectiveness it should have mainly short connections between the nerve cells. Our research suggests that a combination of different lengths of neural projections is essential.
"It is particularly interesting that we made the same observations in both the primate and the worm as their brains are very different in terms of shape and size."
Although it is too early for the research to have direct clinical applications, the researchers suggest that it may eventually contribute towards insights into the diagnosis and possibly the treatment of patients with Alzheimer's and autism if more information about neural networks - and specifically what the long and short nerve fibres do in the brain - is garnered.
One potential development could be a predictive test for the conditions, which examines and analyses a patient's brain organisation, aiding diagnosis and possibly showing how the condition may develop over the coming years.
The study is the most comprehensive yet to look at the spatial organisation of the nervous system in primates and worms.
翻译：
有关大脑学习的新发现
近日，科学家们在大脑活动信息领域的研究中有了新发现，这终将在诸如老年痴呆症，自闭症等脑部疾病的诊治中给予我们提示。
英国纽卡斯尔大学和德国Bremen国际大学的联合研究揭示了一种主导性理论，即神经系统主要通过大多非常短的神经纤维通路，连接神经细胞或神经元及效应。除了研究之外，包含全世界灵长类动物及蠕虫的脑部解剖学研究的高精尖公共电脑分析数据库也应运而生，其中详尽的讯息一同说明了长的神经纤维通路，对整个大脑功能而言，与短神经通路一样至关重要。
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作者:admin@医学,生命科学 2011-02-09 17:14
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