Grey Matter vs White Matter

This week’s post is about the cells that make up our brain. You might already know (especially if you read this post) that our brain cells are divided into two types: grey matter and white matter.

Grey matter is another name for the brain cell bodies.

White matter is made up from all of the brain cell axons – the long arms of the cells which connect them to each other.

The image below of a cross section of the brain shows you how much of each type of matter is present, and where they are distributed within the cortex.


As you can see, most of the grey matter is located on the surface of the cortex, with most of the white matter in the centre (with the exception of grey matter medial temporal lobe structures such as the hypothalamus). They are also both present in the spinal cord, with the central spinal column made from grey matter, and surrounded by white matter tracts. About 40% of the brain is made from grey matter, and various neuroimaging studies have shown that these areas are responsible for motor coordination, vision, memory, and decision making.

In research into psychological disorders, it is important to find out whether mainly grey or white matter is affected. For example in anorexia, this would be useful to establish, as if mainly grey matter is lost then it would suggest abnormal function of body processing areas within the brain, whereas if it was mainly white matter it suggests it is the connections between areas involved in body processing are affected. Fonville et al (2014) investigated this and found that grey matter is reduced in anorexia patients, so could be involved in the onset of the disorder. However, they also concluded that there has not been enough research into how white matter is affected, and whether these levels return to normal after recovery. This research is still in early days, and more needs to be done in order to find a more definitive answer about the roles of white and grey matter in anorexia.

I hope you found this post interesting, and thanks for reading!

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