Your brain works through a series of tiny electrical signals,
which are often called "brain waves" or "brain activity". MEG, or
MagnetoEncephaloGraphy is non invasive and uses a machine which sits outside the head to measure brain
activity and produce an 'activity map' of this activity.
The procedure is entirely painless and has no known side effects. You won’t feel any
differently afterwards and you won’t need to change your activities or
rest after your scan.
People have MEG scans for many different reasons. They can help answer questions such as:
-
What activity is the brain producing and where in the brain does it come from? For example, MEG can be used to measure brain activity associated with relaxation, migraine or epilepsy.
-
Which part of the brain undertakes different tasks? For example, MEG can determine exactly which bit of your brain controls actions such as speaking or moving arms and legs.
-
How does the brain work?MEG researchers are working to develop their understanding of the way in which the brain functions, both normally
and when something goes wrong.
In some cases, yes, as MEG and MRI tell you different
things about the brain. An MRI scan (Magnetic Resonance Image) only
gives you information about the structure of the brain and nothing about its functioning. A MEG scan, on the other hand, can be used to tell you the
locations in the brain that were active during a certain task and also
at what point in time they were active.
Generally, you do not need to do anything before your
scan - you can eat, drink and go about your daily routine as normal.
On the day - you should dress in comfortable clothes. Before your scan you will be
asked to remove any metal objects you are wearing - this is because
metal objects interfere with the MEG machine. These would include
watches, coins, credit cards, jewelry, glasses and clothes that
contain metal (e.g. tops with zips, bras). It is therefore a good idea
to avoid wearing any clothes that contain metal and if you have contact
lenses wear them instead of your glasses. If you are on medication, you
should continue to take it as normal UNLESS your doctor has
told you not to. If you have a mobile phone, you should turn it off
when you arrive at the MEG unit, as it also interferes with the MEG
scanner.
- When you arrive, one of the MEG team will meet you,
explain what will happen and answer any questions you have
- You will have three coils (placed on a Velcro headband) attached to your head - these are used to determine exactly where your head is in the
scanner whilst your brain activity is recorded
- You will then be taken
into the MEG room. In the MEG room you will sit on a chair, which moves
you up slightly so that the top of your head is in the MEG helmet.
You will be told when the scan starts and to keep very still during
the scan (a cushion might be put around your head to help you keep
still). You may be asked to perform a task while you are being scanned,
such as tapping your fingers, or looking at pictures
- After your scan
you will leave the MEG room and you will sit on a chair while a pen is
traced around your head. This will allow us to produce an accurate computer model of
the shape of your head which, when compared to an MRI scan, will allow us to compare brain activity with the structure of your brain.
Your brain waves are directly displayed on a computer
screen whilst you're in the MEG scanner. You can ask the technician if
you can view them when the recording has finished. However,
an in-depth analysis of your brain waves and the procedures that we use
to find out which areas in the brain were active is very
time-consuming, so you won’t be given any results on the day. For
patients, the results will be sent to their doctor, who will contact
them when they are ready. If your MEG scan was for research only, then
the scan will be used as part of a research project and the
results will be published in a scientific journal.
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