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High-frequency Broadband Modulations of Electroencephalographic Spectra.

Onton J, Makeig S - Front Hum Neurosci (2009)

Bottom Line: High-frequency cortical potentials in electroencephalographic (EEG) scalp recordings have low amplitudes and may be confounded with scalp muscle activities.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.

View Article: PubMed Central - PubMed

Affiliation: Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA.

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 ( approximately 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.

No MeSH data available.


Broadband modulators of a representative data set with higher sampling rate. This decomposition of a data set acquired with a sampling rate of 512 Hz (from a different subject than Figure 2) allowed an upper frequency analysis limit of 256 Hz, allowing examination of broadband patterns between 128 Hz and 256 Hz. Negative spikes at 60 Hz and 180 Hz in some templates are residual effects of 60-Hz line noise. Note that IM9 (bottom row) has no effect above 150 Hz, while the modulatory effect of IM3 (middle row) is still increasing at 256 Hz.
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Figure 5: Broadband modulators of a representative data set with higher sampling rate. This decomposition of a data set acquired with a sampling rate of 512 Hz (from a different subject than Figure 2) allowed an upper frequency analysis limit of 256 Hz, allowing examination of broadband patterns between 128 Hz and 256 Hz. Negative spikes at 60 Hz and 180 Hz in some templates are residual effects of 60-Hz line noise. Note that IM9 (bottom row) has no effect above 150 Hz, while the modulatory effect of IM3 (middle row) is still increasing at 256 Hz.

Mentions: To determine the upper frequency limit of the broadband IM phenomena, we recorded and analyzed three additional experimental sessions recorded with an EEG sampling rate of 512 Hz. In each session, we again found broadband IMs whose upper frequency limits varied between 150 Hz and ≥256 Hz. Sample broadband IMs from one of these sessions is shown in Figure 5.


High-frequency Broadband Modulations of Electroencephalographic Spectra.

Onton J, Makeig S - Front Hum Neurosci (2009)

Broadband modulators of a representative data set with higher sampling rate. This decomposition of a data set acquired with a sampling rate of 512 Hz (from a different subject than Figure 2) allowed an upper frequency analysis limit of 256 Hz, allowing examination of broadband patterns between 128 Hz and 256 Hz. Negative spikes at 60 Hz and 180 Hz in some templates are residual effects of 60-Hz line noise. Note that IM9 (bottom row) has no effect above 150 Hz, while the modulatory effect of IM3 (middle row) is still increasing at 256 Hz.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2806183&req=5

Figure 5: Broadband modulators of a representative data set with higher sampling rate. This decomposition of a data set acquired with a sampling rate of 512 Hz (from a different subject than Figure 2) allowed an upper frequency analysis limit of 256 Hz, allowing examination of broadband patterns between 128 Hz and 256 Hz. Negative spikes at 60 Hz and 180 Hz in some templates are residual effects of 60-Hz line noise. Note that IM9 (bottom row) has no effect above 150 Hz, while the modulatory effect of IM3 (middle row) is still increasing at 256 Hz.
Mentions: To determine the upper frequency limit of the broadband IM phenomena, we recorded and analyzed three additional experimental sessions recorded with an EEG sampling rate of 512 Hz. In each session, we again found broadband IMs whose upper frequency limits varied between 150 Hz and ≥256 Hz. Sample broadband IMs from one of these sessions is shown in Figure 5.

Bottom Line: High-frequency cortical potentials in electroencephalographic (EEG) scalp recordings have low amplitudes and may be confounded with scalp muscle activities.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.

View Article: PubMed Central - PubMed

Affiliation: Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA.

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 ( approximately 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.

No MeSH data available.