R. Douglas Fields has an article in March’s Scientific American that reviews his research findings over the past few years and makes an interesting case for the importance of previously ignored white matter in brain processes. The difference between white matter and gray matter is that white matter is primarily composed of myelinated axons while gray matter is composed of the cell bodies that do the information processing. White matter has a lot to do with coordinating how disparate brain regions communicate with each other. His findings, which utilize a new imaging technique called diffusion tensor imaging (DTI), suggest that white matter development and malformation directly affect learning and mental illness.
Few axons are covered with myelin at birth. More are insulated over time, from the back of the cerbral cortex to the front… Basic functional areas such as vision (back) are completed before age 4, followed by language and, last, self-control (forehead).
Doctors have always wondered why schizophrenia typically develops during adolescence[…] this is when the forebrain is being myelinated. The neurons there have largely been established, but the myelin is changing, making it suspect. In addition, nearly 20 studies in recent years have concluded that white matter is abnormal in several regions of the schizophrenic brain. And when gene chips – tiny diagnostic devices that can survey thousands of genes at a time – recently became available, researchers were startled to discover that many of the mutated genes linked to schizophrenia were involved in myelin formation.
The question remains whether or not these findings result in abnormal processing or vise versa. Either way, the article certainly piqued my interest. There are an estimated 10 – 15 times more glia than neurons. It seems reasonable that a malfunction in the neural support system may have important psychological effects.