The other half of the brain
The other half of the brain
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DOI：
10.1038/scientificamerican0404-54
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发表时间：
2004-04-01
影响因子：
3
通讯作者：
Fields, RD
中科院分区：
文献类型：
--
作者：
Fields, RD
其中一位受人尊敬的科学家对这颗珍贵的大脑进行了切片检查。加州大学伯克利分校的戴蒙德说。她发现它的神经元（神经细胞）的数量或大小没有任何异常。但在负责高级认知的联合皮层中，她确实发现了数量惊人的非神经元细胞，即胶质细胞，其浓度远远高于阿尔伯特大脑中的平均浓度。奇怪的好奇心？也许不是。越来越多的证据表明，神经胶质细胞发挥的作用远比历史上想象的要重要得多。几十年来，生理学家一直专注于神经元作为大脑的主要沟通者。尽管神经胶质细胞的数量是神经细胞的九倍，但它们被认为只有维持作用：将营养物质从血管带到神经元，维持大脑中离子的健康平衡，并抵御逃避免疫系统的病原体。在神经胶质的支持下，神经元可以通过称为突触的微小接触点自由交流，并建立起一个连接网络，让我们能够思考、记忆和高兴地跳跃。如果关于神经胶质的新发现得到证实，这种长期存在的大脑功能模型可能会发生巨大变化。在过去的几年里，敏感的成像测试表明，神经元和神经胶质从胚胎发育到老年都在进行双向对话。胶质细胞影响突触的形成，并帮助确定哪些神经连接随着时间的推移变得更强或更弱;这种变化对于学习和储存长期记忆至关重要。最新的研究表明，神经胶质细胞也在它们之间进行交流，在一个独立但与神经网络平行的网络中，影响大脑的表现。神经科学家们对过快地赋予神经胶质以新的重要性持谨慎态度，但他们对大脑的一半以上基本上未被探索的前景感到兴奋，并且可能包含关于大脑如何工作的信息宝库。
One of the respected scientists who examined sections of the prized brain was Marian C. Diamond of the University of California at Berkeley. She found nothing unusual about the number or size of its neurons (nerve cells). But in the association cortex, responsible for high-level cognition, she did discover a surprisingly large number of nonneuronal cells known as glia—a much greater concentration than that found in the average Albert’s head. An odd curiosity? Perhaps not. A growing body of evidence suggests that glial cells play a far more important role than historically presumed. For decades, physiologists focused on neurons as the brain’s prime communicators. Glia, even though they outnumber nerve cells nine to one, were thought to have only a maintenance role: bringing nutrients from blood vessels to neurons, maintaining a healthy balance of ions in the brain, and warding off pathogens that evaded the immune system. Propped up by glia, neurons were free to communicate across tiny contact points called synapses and to establish a web of connections that allow us to think, remember and jump for joy.That long-held model of brain function could change dramatically if new findings about glia pan out. In the past several years, sensitive imaging tests have shown that neurons and glia engage in a two-way dialogue from embryonic development through old age. Glia influence the formation of synapses and help to determine which neural connections get stronger or weaker over time; such changes are essential to learning and to storing long-term memories. And the most recent work shows that glia also communicate among themselves, in a separate but parallel network to the neural network, influencing how well the brain performs. Neuroscientists are cautious about assigning new prominence to glia too quickly, yet they are excited by the prospect that more than half the brain has gone largely unexplored and may contain a trove of information about how the mind works.