Measuring the magnetic signature of brain activity with millisecond precision.
The brain's neuronal activity is associated with magnetic fields that pass essentially unimpeded through the skull, resulting in a undistorted signature of neural activity that can be recorded at the scalp level. Magnetoencephalography (MEG) measures tiny fluctuations in these magnetic fields using an array of extremely sensitive Superconducting QUantum Interference Devices (SQUIDs). This magnetic signal is especially useful for spatial localisation of the underlying brain activity, as well as detecting high-frequency oscillations.
OHBA houses a state-of-the-art VectorViewTM system from Swedish-Finnish manufacturer Elekta-Neuromag. This consists of 306 SQUID measurement channels, which simultaneously measure the magnetic field and magnetic field gradients (spatial variation) around the head at up to 5 kHz. Equipment and software for co-registering the MEG data to individual structural and functional MR scans are available in the MEG laboratory. As well as the 306-channel system itself, dedicated systems can deliver high-quality visual and auditory stimuli. Fibre-optic button boxes are also used for monitoring the behavioural responses of volunteers. A integrated 128-channel Electroencwephalography (EEG) system can measure scalp-potentials during the MEG experiment, where the EEG signals are recorded in the same dataset as the MEG channels. The MEG system is also equipped with a fully integrated high-precision eye-tracking system.