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One study, for instance, found a relationship between white matter structure and IQ, the authors of which concluded that “cognitive function correlates with greater fiber organization.” Similarly, other scientists have found links between the quality of white matter in an adult’s brain and their reading ability. This relatively new technology has been used to look for links between white matter and cognitive outcomes.
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With this technology, the microstructure of white matter can be viewed more tightly packed fibers with thicker myelin coats give stronger DTI signals. However, in tracts that are oriented in parallel and covered in myelin, it is more likely to move along them, rather than side to side. Image credit: Thomas SchultzĭTI is based on the premise that, in normal brain tissue, water is equally likely to travel in any direction. Share on Pinterest DTI image showing white matter tracts. He showed that disrupting the genetic control of oligodendrocytes could produce striking behavioral changes similar to those seen in schizophrenia. Evidence of this came in a paper published in 2007 by Dr. Whether these changes are the cause of the condition or a consequence of the abnormal brain function is yet to be understood, but it is probably an intertwined two-way path. Some scientists believe that this might be more than a coincidence. Schizophrenia tends to develop during adolescence, a time when the forebrain is finally being given its myelin coating. In fact, more recently, it has been shown that white matter tracts across the majority of the brain are disrupted in schizophrenia. Other studies have investigated white matter post-mortem, with some demonstrating abnormalities in white matter tracts and decreased numbers of oligodendrocytes in some regions of the brain. One study that investigated 6,000 genes in the prefrontal cortex of schizophrenic brains provided damning evidence: of the 89 genes found to be abnormally regulated, 35 were involved in myelination. One of the most studied psychiatric conditions in relation to white matter is schizophrenia. White matter has even been implicated in stuttering and tone deafness. For instance, the immune systems of individuals with Guillain-Barré syndrome and multiple sclerosis attack myelin, causing a gradually worsening weakness that can end in paralysis.īut more recently, changes in myelin have been linked to a number of psychiatric conditions, such as schizophrenia, major depression, autism, post-traumatic stress disorder, Alzheimer’s disease, dyslexia, attention-deficit hyperactivity disorder, obsessive-compulsive disorder, and Tourette’s. Some scientists theorize that the limited myelination of these areas in youth might account for teenagers’ inability to make appropriate adult decisions.Īs more scientific interest has been lavished on white matter, it has become clear that it is far from being a passive chunk of cabling it is dynamic – its volume grows and shrinks with experience, it processes information – not just mindlessly passing data between points.Ĭertain conditions have long been associated with damage to the myelin sheath. The frontal lobes are important for planning, reasoning, and judgment. At birth, myelin coverage is relatively sparse myelination moves in a wave, first coating the white matter in the cerebral cortex nearest the nape of the neck and gradually moving forward, finally coating the frontal lobes in our mid to late 20s. In the brain, myelin is laid down by cells called oligodendrocytes. In fact, myelinated nerves can carry impulses up to 100 times faster than non-myelinated fibers. In myelinated nerves, rather than an impulse traveling along the length of the cell as it does in gray matter, it can to leap from node to node, increasing the velocity of conduction.Īs the primary messenger service of the brain, myelination allows white matter to pass notes between distant regions at breakneck speed. Myelin coats the surface of all the nerve cells, leaving small gaps – also known as the nodes of Ranvier – every millimeter or so. Share on Pinterest Myelinated axon compared with demyelinated axon.