Functional MRI

In the last 20 years we have been using functional MRI (fMRI) at Epilepsy Society's Chalfont Centre to map where different functions such as language and vision occur in the brain. For example our research has enabled us to see exactly which part of the brain we use if we want to think of words, name objects or describe a picture. This ability to visualise the communication and thought networks in the brain is enabling us to protect these during surgery and assess how some medications may affect our speech and cognitive abilities.

Language is a critical brain function for communication and thought, for understanding speech and written words, speaking and writing. Language functions are carried out in the temporal and frontal lobes of the brain and, in the majority of people, language is primarily carried out on the left side of the brain.

We use functional MRI (fMRI) to see where in the brain's different functions are occurring. We have developed this at the Chalfont Centre over the last 10 years. For example we can see which parts of the brain a person uses to think of words that start with a particular letter, such as S; or think of the names of objects that are shown as pictures or described. In this way we can pick out different parts of the brain responsible for different language functions and we can also visualise the nerve fibres in the brain that join these parts together.

We have shown that the earlier the age at which the epilepsy starts, the more the language networks in the front parts of the brain are disrupted. For individuals having surgical treatment of their epilepsy, we can now visualise the location of these eloquent brain areas and the critical nerve pathways joining them together, so that surgery may be planned to avoid causing damage to them.

Using these methods, we can see how some medications may affect these functions. One side effect from some epilepsy medication may be a difficulty in thinking of words. The medication may affect the parts of the brain that deals with language function. Doing a language fMRI test before and after taking a single dose of medication can show the effects of the medication on the working of this part of the brain.

The effect that a medication may have can vary enormously from person to person. If we are worried about side effects, we can give a person a test dose of a drug we are considering and then carry out a language fMRI. If we see a bad effect we know to steer away from that medication or to use it very cautiously. We can also ensure that people are on the look-out for any side effects themselves so they can report back and we can adjust their medication accordingly.