White matter in the brain is being shown to have possible impacts on learning processes and psychological disorders, including depression and schizophrenia. But, there are still unanswered questions.
White matter allows signals to be passed through the brain essentially making the brain work. It is becoming increasingly clear to scientists that white matter in the brain can change when doing complex learning activities. Previously, gray matter was thought to contain the sole cognitive functions of the brain, but MRIs are discovering that white matter also plays a role.
What is white matter?
White matter is composed of millions of bundles of nerve fibres that connect neurons to different regions of the brain. The bundles of nerve fibres, also known as axons, are formed and are protected by Myelin, which surrounds the axons.
Grey matter is linked to information processing and white matter is correlated with the networking between processing centers. White matter also strengthens the ability to integrate and assimilate information between the centers exemplified by increased language skills.
Myelin is made up of tightly compressed non-neuronal cells that are essential to transmitting electrical impulses through the dense network of nerve pathways in white matter. Complex learning activities like reading, juggling, exercising, or playing music can activate the myelin.
Dr. R. Douglas Fields, Chief of the Nervous System Development and Plasticity Section at the National Institutes of Health, has completed several studies that show an increase in myelin within the white matter of the brain can increase the speed of electrical impulses, ultimately improving productivity.
Structural changes in white matter after learning complex tasks
Magnetic Resonance Imaging (MRI) tests have shown that white matter can change after learning complex tasks. When a difficult activity is completed, the level of myelin increases. This shows that white matter has the potential to transform along with learning, which could help to prevent degeneration of the brain later on in life.
A 2015 study on changes in white brain matter by the National Center for Biotechnology Information used the examples of a professional musician and a juggler to show how white matter works:
“The greatest changes were seen in parts of the brain that were not yet fully myelinated. Similarly, adult subjects showed increased white matter structural organization in a brain region important for visuo-motor control six week after learning to juggle.”
Decrease in white matter volume after the age of 50
Myelination is more active when the brain is developing. Field’s study stated that only 29 per cent of the brain’s myelin remains after sexual maturity, indicating that white matter changes less in adults. The remaining myelin is used for repairs in cognitive function and can be used for complex learning tasks if individuals dedicate time to learn new things as they get older.
Myelin must undergo cell division in order to build white matter in the brain. These cell cycles increase by eight hours each day from birth. Therefore, as we age, it takes longer for those cells to divide, leading to potential brain degeneration.
The effect of mental disorders on white matter of the brain
Recent studies on the white matter of the brain drew parallels with connection to mental disorders including depression and schizophrenia. Research of psychological disorders focuses more on synaptic transmission, but myelin cells could be a contributor as well.
Limited research has been determined about white matter in the brain and much remains to learn. A study on the intelligence of men and women from the University of California reported that women have ten times the amount of white matter as compared to men. Is white matter indicative of gender? Can an increase in myelin help slow degenerative diseases like Alzheimers and Dementia? This remains to be seen, but what we have confirmed is that white matter does, indeed, matter.