Magnetoencephalography (MEG) is a noninvasive method of recording magnetic fields that result from brain electrical activity. The information it provides is thus closely related to the information in the electroencephalogram (EEG). There are a number of important basic and clinical research questions that must be asked of MEG, a relatively new technology, before its capacities and applicability to neuropsychiatric problems will be understood. We will briefly review the substrate that is thought to be measured, the instrument and its applications, and one of the auditory evoked responses that has been successfully recorded by MEG.
See also p 565.
Brain electrical activity has traditionally been studied with EEG. It is believed that the EEG signal comes from fluctuations in the resting membrane potential of the dendrites and cell bodies of cortical neurons, primarily pyramidal cells located in layer V, rather than from the action potentials of axons. Movements of ions along