Measuring the magnetic fields produced by neuronal activity in the brain
Magnetoencephalography (MEG) is an imaging technique which measures the magnetic fields produced by neuronal activity in the brain. It utilise’s extremely sensitive devices – superconducting quantum interference devices (SQUIDs) to achieve this. MEG measurements are commonly used in research and increasingly in clinical settings. The technique has many applications. Examples include the determination of function in various parts of the brain, neuro-feedback and the localization of pathology.
MEG has been in development since the 1960s but it floundered by the lack of appropriate technology. Interest in it has been reignited by recent advances in computing algorithms and hardware. It now offers good spatial resolution as well as extremely high temporal resolution (better than 1 ms). Information regarding neuronal activity accessible from outside of the brain differs for electrical and magnetic fields. Thus MEG derived information complements other brain activity measurement techniques such as the electroencephalography (EEG).
Because magnetic signals emitted by the brain are tiny – in the order of a few femtoteslas – adequate shielding from external magnetic signals is necessary. This includes shielding against the forces of the Earth‘s magnetic field. The synchronous recording of both EEG and MEG demands special equipment such as flat-type and (particularly important) demagnetized electrodes as well as non-magnetic, battery-powered amplifiers. All of these features are included in the product range offered by Brain Products. Additionally, we offer real-time synchronization tools to combine EEG and MEG data for accurate offline processing. See http://www.brainproducts.com/products_by_apps.php?aid=2 for further details.