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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.


Difference between positive and negative correlation-weighted IC equivalent-dipole densities of IMs whose median weights, across 14 emotion imagination periods, were positively or negatively correlated with behaviorally rated emotion valence. Regions of non-significant density differences were masked using permutation statistics (p > 0.003, uncorrected). Areas of significant density difference between positive and negative correlation densities are colored yellow/red, indicating broadband power increases during positive-valence emotions, or cyan/blue, indicating broadband power increases during negative-valence emotions. White integers near each slice image give the MNI z-axis coordinates; yellow text, the nearest Talairach z-axis values. In these images, left is left. Weights for ‘compassion’ were not included (see text).
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Figure 10: Difference between positive and negative correlation-weighted IC equivalent-dipole densities of IMs whose median weights, across 14 emotion imagination periods, were positively or negatively correlated with behaviorally rated emotion valence. Regions of non-significant density differences were masked using permutation statistics (p > 0.003, uncorrected). Areas of significant density difference between positive and negative correlation densities are colored yellow/red, indicating broadband power increases during positive-valence emotions, or cyan/blue, indicating broadband power increases during negative-valence emotions. White integers near each slice image give the MNI z-axis coordinates; yellow text, the nearest Talairach z-axis values. In these images, left is left. Weights for ‘compassion’ were not included (see text).

Mentions: Next, we asked where in the brain median power changes occurring during emotion imagination periods were positively or negatively correlated with the behaviorally rated valence of the emotion labels. To construct Figure 10, median weights for each broadband gamma IM were correlated with the rated emotional valence of each emotion term. Then, the locations of all IC equivalent dipoles significantly modulated by these broadband IMs (see Materials and Methods) were weighted by the absolute value of this correlation to create two correlation-weighted dipole density plots (in correlation-weighted dipoles/cm3) for positive and negative correlations, respectively. Figure 10 shows the difference between those two density images, masked for significance (p < 0.003, uncorrected) by randomly permuting positive and negative correlation values. IMs positively correlated with valence (i.e., ICs whose median IM broadband power was stronger during imagination of positive-valence emotions) were relatively dense in bilateral mid-temporal cortex (BA20/21), while IMs negatively correlated with rated emotional valence (i.e., ICs whose IMs exhibited larger power during imaginative experience of negative-valence emotions) were relatively dense in bilateral occipital cortex near to but not including the occipital midline (BA17/18).


High-frequency Broadband Modulations of Electroencephalographic Spectra.

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

Difference between positive and negative correlation-weighted IC equivalent-dipole densities of IMs whose median weights, across 14 emotion imagination periods, were positively or negatively correlated with behaviorally rated emotion valence. Regions of non-significant density differences were masked using permutation statistics (p > 0.003, uncorrected). Areas of significant density difference between positive and negative correlation densities are colored yellow/red, indicating broadband power increases during positive-valence emotions, or cyan/blue, indicating broadband power increases during negative-valence emotions. White integers near each slice image give the MNI z-axis coordinates; yellow text, the nearest Talairach z-axis values. In these images, left is left. Weights for ‘compassion’ were not included (see text).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 10: Difference between positive and negative correlation-weighted IC equivalent-dipole densities of IMs whose median weights, across 14 emotion imagination periods, were positively or negatively correlated with behaviorally rated emotion valence. Regions of non-significant density differences were masked using permutation statistics (p > 0.003, uncorrected). Areas of significant density difference between positive and negative correlation densities are colored yellow/red, indicating broadband power increases during positive-valence emotions, or cyan/blue, indicating broadband power increases during negative-valence emotions. White integers near each slice image give the MNI z-axis coordinates; yellow text, the nearest Talairach z-axis values. In these images, left is left. Weights for ‘compassion’ were not included (see text).
Mentions: Next, we asked where in the brain median power changes occurring during emotion imagination periods were positively or negatively correlated with the behaviorally rated valence of the emotion labels. To construct Figure 10, median weights for each broadband gamma IM were correlated with the rated emotional valence of each emotion term. Then, the locations of all IC equivalent dipoles significantly modulated by these broadband IMs (see Materials and Methods) were weighted by the absolute value of this correlation to create two correlation-weighted dipole density plots (in correlation-weighted dipoles/cm3) for positive and negative correlations, respectively. Figure 10 shows the difference between those two density images, masked for significance (p < 0.003, uncorrected) by randomly permuting positive and negative correlation values. IMs positively correlated with valence (i.e., ICs whose median IM broadband power was stronger during imagination of positive-valence emotions) were relatively dense in bilateral mid-temporal cortex (BA20/21), while IMs negatively correlated with rated emotional valence (i.e., ICs whose IMs exhibited larger power during imaginative experience of negative-valence emotions) were relatively dense in bilateral occipital cortex near to but not including the occipital midline (BA17/18).

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.