AUTHOR=Onton Julie A., Makeig Scott TITLE=High-frequency broadband modulation of electroencephalographic spectra JOURNAL=Frontiers in Human Neuroscience VOLUME=3 YEAR=2009 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/neuro.09.061.2009 DOI=10.3389/neuro.09.061.2009 ISSN=1662-5161 ABSTRACT=

High-frequency cortical potentials in electroencephalographic (EEG) scalp recordings have low amplitudes and may be confounded with scalp muscle activities. EEG data from an eyes-closed emotion imagination task were linearly decomposed using independent component analysis (ICA) into maximally independent component (IC) processes. Joint decomposition of IC log spectrograms into source- and frequency-independent modulator (IM) processes revealed three distinct classes of IMs that separately modulated broadband high-frequency (∼15–200 Hz) power of brain, scalp muscle, and likely ocular motor IC processes. Multi-dimensional scaling revealed significant but spatially complex relationships between mean broadband brain IM effects and the valence of the imagined emotions. Thus, contrary to prevalent assumption, unitary modes of spectral modulation of frequencies encompassing the beta, gamma, and high gamma frequency ranges can be isolated from scalp-recorded EEG data and may be differentially associated with brain sources and cognitive activities.