Grey matter is fundamental to our minds - indeed, it's so important that the term is often used to refer the brain as a whole. But it turns out that white matter may be where our thinking happens.
Even though the term "grey matter" is fairly well-known, it's far less well-known what it actually is. Grey matter is one of the two main parts of the central nervous system, and it refers to all the neural cell bodies in the brain and along the spinal cord. Gray matter is found all over the surface of the brain, and it translates all the sensory information the body receives into chemical data that the brain's synapses can interpret.
The other part of the central nervous system is white matter, which is the long strands of nerve cell extensions known as axons. The axons carries information from one grey matter region to another, making them essentially the brain's messenger service. As such, cognitive scientists had long dismissed white matter as an unimportant cog in the brain's proper function, something that did its job well enough but wasn't important to thinking or learning.
That view is now changing. Researcher R. Douglas Fields has discovered the structure of white matter actually changes in response to how much work a person puts into learning a complex task. In MRI studies, Fields found that if a person was, say, a musician, the amount of change in his or her white matter would be directly related to how many hours he or she spent practicing an instrument.
Intriguingly, the most change occurs in regions of white matter that lack myelin, which is the fatty substance that serves as electrical insulation around most of the axons. The exact implications of these findings aren't clear yet - Fields wants to conduct further studies that will hopefully clarify what active role white matter plays in communication information between neurons, something that was previously thought to be an entirely passive activity. He also hopes to better understand what role malfunctioning white matter might play in diseases of the mind.
[Read the full paper via Science]