EEG and MEG

Electroencephalography (EEG) and Magnetoencephalography (MEG) are two very similar techniques used to record activity in the brain. Both rely on the tiny electrical impulses produced by the individual neurons in the brain. The EEG measures the electrical activity directly while the MEG measures the equally tiny magnetic field produced by this electrical  activity. This is done by attaching a number of electrodes to a subjects head which lead back to a computer. scientists are then able to infer activity based on increases or decreases of activity in different areas of the brain.

These scans are usually administered together due to their similarity in how they measure activity. This can be used to help confirm readings since there are two measurements versus one with other techniques. They can also help compensate for each others short comings, for example, the EEG’s readings can be influenced by the position of electrode relative to the electrical impulse but the MEG is not.

These scans are a favorite of researchers because they have the best temporal resolution out of any of the neural imaging techniques currently being used. This means that a neural response can be measure within milliseconds of administering a stimuli. It is also a very non-intrusive method of studying the brain save for the glue that gets stuck in your hairs. These techniques are limited, however, in how precisely they can localize the activation they record.
    

Image source:                                             http://www.mayoclinic.com/health/medical/IM03978  http://www.waisman.wisc.edu/cores/imaging/Behavioral.html

 

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