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Basic Physics and Physiology of MEG and EEG 

Basic Physics and Physiology of MEG and EEG
Chapter:
Basic Physics and Physiology of MEG and EEG
Author(s):

Riitta Hari

, and Aina Puce

DOI:
10.1093/med/9780190497774.003.0003
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date: 26 February 2021

This chapter outlines the general principles of physics and physiology underlying MEG and EEG signals. It introduces charges and electric currents, and the associated electric potentials and magnetic fields. Basic laws of electricity and the relationships between magnetic and electrical fields are examined. The phenomenon of superconductivity is introduced and related to measurements of MEG signals with SQUID sensors. The effects of various tissues and current configurations on MEG and EEG signals are described. Basic principles of source localization, that is modeling the neuronal sources of the observed MEG and EEG signals are described. The spatial accuracy versus precision of source localization is illustrated. Volume conduction, current spread in the different compartments of the body is explained.

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