Chapter

High-Resolution EEG

Paul L. Nunez and Ramesh Srinivasan

in Electric Fields of the Brain

Second edition

Published in print January 2006 | ISBN: 9780195050387
Published online May 2009 | e-ISBN: 9780199865673 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780195050387.003.0008
 High-Resolution EEG

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The source distribution underlying any EEG waveform need not be generated by a single dipole source located in a restricted cortical area. High-resolution EEG methods apply spatial filters to scalp data rather than fitting the data to a source model. High-resolution filters isolate those aspects of the EEG that are associated with superficial cortical tissue immediately surrounding the electrode. Signals removed by applying this spatial filter can generally be eliminated as local source candidates. This chapter demonstrates theoretically that the surface Laplacian is a band-pass filtered representation of source activity, as compared to scalp potentials dominated by very low spatial frequencies in the source distribution. The surface Laplacian increases the sensitivity of each electrode to nearby superficial cortical sources. Such Laplacian-identified sources are likely to be radial dipoles in proximal gyral surfaces. High-resolution EEG offers the advantage of viewing cortical dynamics at smaller spatial scales than are possible with raw scalp potentials.

Keywords: spatial filter; Laplacian; spline-Laplacian; band pass spatial filter; localized sources; distributed sources; transfer function; gyral sources

Chapter.  15563 words.  Illustrated.

Subjects: Neuroscience

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