Article Figures & Data
Figures
- Figure 1.
Separation of oscillatory and scale-free ECoG. A, Scale-free and oscillatory components of macaque ECoG signals were separated into broadband and narrow-band spectral distributions in the frequency domain. B, From the oscillatory spectrogram, band-limited power fluctuations were extracted from a specific frequency of interest (e.g., alpha). From the scale-free spectrogram, broadband power fluctuations were extracted from either the LF range (1–15 Hz) or the HF range (15–100 Hz).
- Figure 2.
Broadband power correlations for scale-free ECoG. A, Seed-based correlation patterns of the LF BBP and the alpha BLP in eyes-closed wakefulness for macaque C. B, Percentage of significantly correlated pairs of channels (left) and the inhomogeneity of cross-correlations between different channels. The asterisk bracket indicates the statistically significant difference between samples (*p < 0.05, **p < 0.01, ***p < 0.001, paired Wilcoxon signed-rank test for percentage and paired t test for inhomogeneity. C, Pattern of correlation in the LF BBP between every channel and the average across all channels. D, Degree of global correlation across three arousal states. Each line represents one session. Relative to sleep, the global correlation in eyes-closed wakefulness was significantly lower (p = 0.014, paired t test). The global correlation in eyes-open wakefulness was further lower (p = 0.018, paired t test) than that in eyes-closed wakefulness.
- Figure 3.
Cofluctuations of LF-BBP and HF-BBP. A, BBP fluctuations in the LF and HF ranges were correlated by r = 0.47 for one typical ECoG channel. B, Correlations between LF-BBP and HF-BBP for all 128 sensors were displayed as a map (left). Right, Percentage of channels showing a significant correlation between LF-BBP and HF-BBP fluctuations for various arousal states.
- Figure 4.
Power fluctuations and correlations of oscillatory and scale-free MEG. A, Alpha BLP, and LF and HF BBP fluctuations (right) were extracted from the spectrograms of the oscillatory and scale-free components (left), respectively. B, Patterns of cross-channel correlations in the alpha BLP or the LF BBP. Each row is a seed-based correlation map displayed as a 2D surface topography.
- Figure 5.
Direct coupling between scale-free EEG and global fMRI. A, Oscillatory and scale-free spectrograms observed with EEG. B, Cross-correlation between the global fMRI and the spectral power fluctuation at every frequency with varying time delay for the oscillatory (top) and scale-free components (bottom). C, Cross-correlations were averaged across frequencies to yield a linear transfer function to relate oscillatory (blue) or scale-free (red) EEG fluctuation to global fMRI activity. The asterisk bracket indicates the statistically significant difference between the two correlation functions within the specified ranges of time delay (*p < 0.001, paired t test).
- Figure 6.
Correlation between fMRI signals and the power fluctuations of scale-free and oscillatory EEG. A, B, Cross-correlations between LF-BBP, HF-BBP, alpha-BLP at every channel and the global fMRI signal as fMRI delayed from EEG by 5 s (A) or 12.5 s (B). Channels with significant or nonsignificant correlation are marked as dark versus gray dots. C, D, Cross-correlations between the global LF-BBP, HF-BBP, alpha-BLP, and the fMRI signal at every voxel as fMRI delayed from EEG by 5 s (C) or 12.5 s (D). Colored bars indicate the correlation coefficient after the Fisher's transformation.
