What is Magnetoencephalography (MEG)?

Magnetoencephalography (MEG) is a form of neuroimaging that maps the tangential components of magnetic fields associated with scalp potentials produced by the brain. These potentials are similar to those that can be recorded as electroencephalograms (EEGs) however the dynamic magnetic components of these potentials contain different information with spatial sampling. Unlike fMRI or PET images that provide indirect or delayed clues to synaptic events through changes in the metabolism or blood flow, magnetoencephalography locates regions of the brain that respond directly to stimuli and yields corresponding time responses at various spatial locations.

To accomplish the above described tasks, a subject is placed into a helmet-like enclosure that houses a semi-spherical array of hundreds of magnetic sensing tools. Because the brain’s dynamic magnetic field is weaker by five orders of magnitude than magnetic background noise, special noise-supressing coil configurations, as well as ultrasensitive detectors, superconducting quantum interference devices (SQUIDs), and shielded chambers are required. These signals from the coils as well as their locations on the semi-spherical grid are employed in solving the inverse problem of establishing the source location of the signals in the brain. These calculations are repeated for different combinations of signals until active regions of the brain are identified with their associated time waveforms. These waveforms are combined with MRI and or fMRI imaging to aid in localization.

Applications of Magnetoencephalography (MEG)

Magnetoencephalography is to study the characteristics of mental patterns such as epilepsy and schizophrenia. It is also helpful in brain research to understand cognitive functioning and to learn which parts of the brain are involved in different tasks.

Related articles:

• Electroencephalogram (EEG)
• Commonly used EEG Electrodes
• Common Challenges of EEG Analysis
• Sources of Biomedical Signals