Investigation of the Cerebral Cortex Using Magnetoencephalography(MEG) Ryusuke Kakigi 1,2 1Department of Integrative Physiology, National Institute for Physiological Sciences 2The Graduate University for Advanced Studies (SOKENDAI) Keyword: 脳磁図 , 脳磁場 , 誘発脳磁図 , 周波数 , オシレーション , magnetoencephalography , MEG , evoked field , frequency , oscillation pp.451-466
Published Date 2015/4/1
DOI https://doi.org/10.11477/mf.1416200162
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Cortical neurons are excited by signals from the thalamus that are conducted via thalamocortical fibers. As the cortex receives these signals, electric currents are conducted through the apical dendrites of pyramidal cells in the cerebral cortex. These electric currents generate magnetic fields. These electric and magnetic currents can be recorded by electroencephalography (EEG) and magnetoencephalography (MEG), respectively. The spatial resolution of MEG is higher than that of EEG because magnetic fields, unlike electric fields, are not affected by current conductivity. MEG also has several advantages over functional magnetic resonance imaging (fMRI). It (1) is completely non-invasive; (2) measures neuronal activity rather than blood flow or metabolic changes; (3) has a higher temporal resolution than fMRI on the order of milliseconds; (4) enables the measurement of stimulus-evoked and event-related responses; (5) enables the analysis of frequency (i.e., brain rhythm) response, which means that physiological changes can be analyzed spatiotemporally; and (6) enables the detailed analysis of results from an individual subject, which eliminates the need to average results over several subjects. This latter advantage of MEG therefore enables the analysis of inter-individual differences.

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