Electrical activity within the brain generates magnetic fields that can be measured outside the head using a technique known as magnetoencephalography (MEG).
How MEG works
MEG recordings of an individual can be made while they are at rest, performing a task or undergoing interventions such as treatment with a specific drug.
The magnetic fields produced by the brain are extremely weak (around a billion times weaker than the magnetic field of a typical fridge magnet) and require extremely sensitive measurement devices to be detected.
MEG systems use special sensors called superconducting quantum interference devices (SQUIDs), which are sensitive enough to pick up minute differences in magnetic fields.
These sensors only work at temperatures below -269°C and so are constantly bathed in liquid helium in order to keep them cold enough to operate.
As well as measuring magnetic fields generated by the brain, SQUIDS are so sensitive that they can pick up fields from the surrounding environment even if they are weak or at a distance. For this reason, our MEG is housed within a specially shielded room that blocks out outside magnetic noise.
The sensors and the liquid helium are held within the white unit above the participant’s head. From here, the sensors measure the magnetic field while the participant responds to the images shown on the screen. These magnetic fields then provide information about the participant’s brain activity during the task.
Optimised environment for brain studies
Our MEG uses a CTF 275 axial gradiometer design, a system which combines physical first-order axial gradiometers with effective third-order noise cancellation delivered by a reference superconducting quantum interference devices (SQUID) array in the dewar.
We have found this system to be a robust and stable platform for studying human brain activity, with a particular emphasis on cortical oscillatory dynamics in health and disease. This has resulted in several successful publications and grant awards for research projects studying both healthy brain function and diseases such as epilepsy, schizophrenia and Alzheimer’s.
The core sensor array is completely refurbished and upgraded with a new set of processing and acquisition electronics installed in a 5m x 4m magnetically shielded room (MSR). This larger room makes it easier to study both challenging patient populations and drug manipulations that require careful physiological monitoring during the experiment.
Coupled with the adjacent clinical research facility within the building, this makes our MEG lab an optimised environment for clinical and pharmacological studies of the brain’s oscillatory dynamics. Find out more about our MEG equipment.