Most of the images created in hospitals using MRI show structural features of the body, but it is also possible to show some information about the oxygen consumption of tissues as well – this is known as functional MRI, or fMRI for short. When the brain is working it needs a good supply of oxygen. The oxygen is carried in the blood in the form of a substance called oxyhaemaglobin. When the oxygen has been used up the remaining substance is called deoxyhaemaglobin.
Rather fortunately for brain researchers, oxyhaemaglobin and dexyhaemaglobin have different magnetic properties, so it is possible to see which parts of the brain are using more oxygen – or working harder.
And here’s a strange fact: one might think that there would then be more deoxyhaemoglobin in the regions of the brain that are working hardest but in fact the opposite is true!
The active regions of the brain need more oxygen, so the blood supply is increased and is increased by so much that there is extra oxyhaemaglobin in the active parts of the brain.
The sequences used in fMRI will pick up this extra blood supply and therefore give us a picture of the active regions of the brain. This technique is called Blood Oxygen Level Dependence, or BOLD, and is widely used by researchers such as those at the MRC, who are looking at the ways our brains carry out certain functions. Hence the lovely images of Jem’s brain solving problems better than Dallas’! .
Rather fortunately for brain researchers, oxyhaemaglobin and dexyhaemaglobin have different magnetic properties, so it is possible to see which parts of the brain are using more oxygen – or working harder.
And here’s a strange fact: one might think that there would then be more deoxyhaemoglobin in the regions of the brain that are working hardest but in fact the opposite is true!
The active regions of the brain need more oxygen, so the blood supply is increased and is increased by so much that there is extra oxyhaemaglobin in the active parts of the brain.
The sequences used in fMRI will pick up this extra blood supply and therefore give us a picture of the active regions of the brain. This technique is called Blood Oxygen Level Dependence, or BOLD, and is widely used by researchers such as those at the MRC, who are looking at the ways our brains carry out certain functions. Hence the lovely images of Jem’s brain solving problems better than Dallas’! .
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