Noninvasive Neurophysiological Imaging with Magnetoencephalography

Abstract

Magnetoencephalography (MEG) is a noninvasive neurophysiological recording technique that is primarily utilized in human studies of system-level brain function. Although the seminal MEG measurements occurred more than 40 years ago, the precision of the instruments and the analytical sophistication of the field have dramatically increased over the past decade. At present, MEG is the only noninvasive high-resolution neurophysiological imaging technique and the only functional brain imaging method to offer both high temporal (<1 ms) and spatial (2–5 mm) resolution. The current chapter will provide a brief historical introduction to MEG and functional magnetic resonance imaging (fMRI), which is the most common method of functional brain imaging. Description of the physical and physiological bases of the signals measured in noninvasive functional imaging will follow, with an emphasis on the neuromagnetic signals quantified in human MEG measurements. An introduction to the most common MEG analysis methods will be presented; and thereafter, several examples of MEG applications will be discussed to illustrate the type of questions often pursued in MEG research and the general areas of study where MEG measurements are making an impact. The chapter will conclude by presenting some new applications for MEG-based functional brain imaging.