MEG

What is MEG?

MEG (magnetoencephalography, ‘meg’ or ‘em-ee-gee’) is a tool for investigating brain functioning in both healthy people and in patients to provide clinicians with information for diagnosis and treatment.

MEG works by measuring the tiny magnetic fields of the brain that are generated from electrical currents produced by brain cells. These magnetic fields are measured and analysed to provide detailed information about the location and function of brain activity. 

Why a MEG scan?

People have MEG scans for many different reasons. MEG can be used to measure brain activity associated with epilepsy, following a concussion or brain injury, or simply at rest. It can also determine which parts of your brain controls actions such as speaking, reading or moving arms and legs.

In some cases, you may need both a MEG and MRI, both of which can take place at Aston University Imaging.

An MRI scan (Magnetic Resonance Image) gives you information about the structure of the brain while a MEG scan, 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.

How to prepare

On the day, please 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 include watches, coins, credit cards, jewellery, 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. We also ask that you do not wear make-up as some make-up contains metal particles. 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.

How does it work?

MEG detects, records and analyses the magnetic fields produced by electrical currents in the brain. The distribution of these magnetic fields is combined with an anatomical image of the brain to help identify the source of activity in the brain.

You will have five small coils attached to your head, which are used to determine exactly where your head is in the scanner whilst your brain activity is recorded. We will then run a digital pen over your scalp to generate a computer image of the shape of your head . We may also attach electrodes to your chest to record your heart beat or around your eyes to record your eye movement.

Whilst the scan takes place, your head will be inside the MEG helmet and you will be asked to keep still, unless instructed to carry out a task such as tapping your fingers. Often you will be seated in a comfortable chair, but you may also be asked to lie on a bed. The MEG system is extremely quiet so we will let you know when a recording is going to start.