Gallery: The brain鈥檚 other half: picturing the white matter
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AS FAR as the internet or phone networks go, bad connections are bad news. Not so in the brain, where slower connections may make people more creative.
Rex Jung at the University of New Mexico in Albuquerque and his colleagues had found that creativity correlates with low levels of the chemical N-acetylaspartate, which is found in neurons and seems to promote neural health and metabolism.
But neurons make up the brain鈥檚 grey matter 鈥� the tissue traditionally associated with thinking power, rather than creativity. So Jung is now focusing his creativity studies on white matter, which is largely made of the fatty myelin sheaths that wrap around neurons. Less myelin means the white matter has a lower 鈥渋ntegrity鈥� and transmits information more slowly.
Several recent studies have suggested that white matter of high integrity in the cortex, which is associated with higher mental function, means increased intelligence. But when Jung looked at the link between white matter and creativity, he found something quite different.
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He used diffusion tensor imaging to study the white matter of 72 volunteers. Unlike MRI, which measures tissue volume, DTI measures the direction in which water diffuses through white matter, an indication of its integrity.
The volunteers鈥� capacity for divergent thinking 鈥� a factor in creativity that includes coming up with new ideas 鈥� had already been tested. Jung found that the most creative people had lower white-matter integrity in a region connecting the prefrontal cortex to a deeper structure called the thalamus, compared with their less creative peers (PLoS ONE, ).
Jung suggests that slower communication between some areas may actually make people more creative. 鈥淭his might allow for the linkage of more disparate ideas, more novelty, and more creativity,鈥� he says.
Other studies have hinted that white matter might be similarly affected in some psychiatric disorders (see 鈥淭he brain鈥檚 other half鈥�). So the result also strengthens the link between creativity and mental illness. One of the triggers for Jung鈥檚 study was the finding that when white matter begins to break down in people with dementia, they often become more creative.
The results are surprising, given that high white-matter integrity is normally considered a good thing, says at the University of California in Los Angeles. He acknowledges that speedy information transfer may not be vital for creative thought. 鈥淪heer mental speed might be good for playing chess or doing a Rubik鈥檚 cube, but you don鈥檛 necessarily think of writing novels or creating art as being something that requires sheer mental speed,鈥� he says.
鈥淪heer mental speed might be good for playing chess, but writing novels requires something different鈥�
Jung emphasises that creativity and intelligence can still go hand in hand. Each appears to be controlled by white matter in a different region. So theoretically, there鈥檚 no reason why someone might not have high integrity in the cortex, producing intelligence, but low integrity between the cortex and deeper brain regions, leading to creative thinking. 鈥淭hey appear to function relatively independently,鈥� he says.
Gallery: The brain鈥檚 other half: picturing the white matter
The brain鈥檚 other half
The ability to picture the quality of the brain鈥檚 connections isn鈥檛 just helping us understand the underpinnings of creativity and intelligence (see main story) 鈥� it is also changing how we think about psychiatric disorders.
White matter has grabbed the spotlight recently thanks to advances in diffusion tensor imaging, which measures the movement of water along nerve tracts in the brain. 鈥淎s the scanners have got faster and the technology has improved, you can now get these beautiful images of fibre connections and integrity,鈥� says Paul Thompson of the University of California in Los Angeles, who created the picture (above) of the brain鈥檚 white matter. 鈥淭his is a new landscape of discovery in brain research.鈥�
That landscape includes mental illness. Differences in the quality of white matter have been observed in people with depression, Alzheimer鈥檚, schizophrenia and bipolar disorder, as well as in some language disorders and stuttering. Changes in how information gets transmitted, due to these differences, could explain the cognitive impairment that is part of many of these disorders.
Most recently, Cynthia Schumann at the University of California in San Diego and her colleagues have shown that in toddlers with autism both grey and white matter grow too much between the ages of 1.5 and 5 years (Journal of Neuroscience, ).
Excess white matter could lead to certain regions of the cortex being 鈥渉测辫别谤肠辞苍苍别肠迟别诲鈥�, which might explain the savant-like abilities seen in some people with autism, suggests Douglas Fields of the National Institute of Child Health and Human Development in Rockville, Maryland, and author of The Other Brain, which details the growing importance of white matter.
