Magnetoencephalography recording and analysis

• Published in: Annals of the Indian Academy of Neurology 2014-03, Vol.17 (5), p.113-119
• Main Authors: Velmurugan, Jayabal, Sinha, Sanjib, Satishchandra, Parthasarathy
• Format: Article
• Language: English
• ISSN: 0972-2327; 1998-3549
• DOI: 10.4103/09722327.128678

Magnetoencephalography (MEG) noninvasively measures the magnetic field generated due to the excitatory postsynaptic electrical activity of the apical dendritic pyramidal cells. Such a tiny magnetic field is measured with the help of the biomagnetometer sensors coupled with the Super Conducting Quantum Interference Device (SQUID) inside the magnetically shielded room (MSR). The subjects are usually screened for the presence of ferromagnetic materials, and then the head position indicator coils, electroencephalography (EEG) electrodes, and fiducials are digitized using a 3D digitizer, which aids in movement correction and also in transferring the MEG data from the head coordinates to the device and voxel coordinates, thereby enabling more accurate coregistration and localization. Thus, MEG source localization can aid clinicians in sublobar localization, lateralization, and grid placement, by evoking the irritative/seizure onset zone. It also accurately localizes the eloquent cortex-like visual, language areas. MEG also aids in diagnosing and delineating multiple novel findings in other neuropsychiatric disorders, including Alzheimer's disease, Parkinsonism, Traumatic brain injury, autistic disorders, and so on.