Despite everything that has been written about the brain, a potentially critical part of this vital organ has been overlooked—until now. The Other Brain examines the growing importance of glia, which make up approximately 85 percent of the cells in the brain, and the role they play in how the brain functions, malfunctions, and heals itself. Long neglected as little more than cerebral packing material, glia (meaning “glue”) are now known to regulate the flow of information between neurons and to repair the brain and spinal cord after injury and stroke. But scientists are also discovering that diseased and damaged glia play a significant role in psychiatric illnesses such as schizophrenia and depression, and in neurodegenerative diseases such as Parkinson’s and Alzheimer’s. Diseased glia cause brain cancer and multiple sclerosis and are linked to infectious diseases such as HIV and prion disease (mad cow disease, for example) and to chronic pain. The more we learn about these cells that make up the “other” brain, the more important they seem to be.

重大疾病的新曙光
　　愛因斯坦天才的祕密關鍵

　　愛因斯坦死後，他的腦成為科學家的研究材料。許多人等著發現他的腦神經細胞異於常人，實際觀察的結果卻與一般人無異。唯一發現的不同點是：腦神經周邊「無關緊要」的膠細胞比常人多一倍。

　　我們在學校學到，神經系統由神經細胞（神經元）組成，負責思考與記憶等高階功能的大腦則匯聚了一大堆神經元。至於旁邊那些黏膠一般的不起眼細胞，只是支撐物而已。

　　一個多世紀以來，科學家確實是這麼相信的。但是近三十年的研究慢慢發現，占人腦至少半數的膠細胞不但有自己獨特的訊息傳遞網絡，還會調控神經元之間的資訊 流通；它們與神經元之間的協同合作，可能才是思考、記憶與創意的源頭。此外，膠細胞還負責防衛病毒、修補神經元損傷，以及引導新生神經纖維恢復與肌肉之間的恰當溝通。