Mean spectral power proportions.

Mean spectral power proportions in the indicated frequency bands within grey matter, white matter and ventricle masks in the low-TR (top) and high-TR (bottom) datasets. Voxelwise spectra were calculated and averaged across all voxels within the respective masks. Row-wise maxima are highlighted in the table. In the low-TR dataset, low-frequency fluctuations up to 0.25 Hz are most pronounced in grey matter, while medium and high frequency oscillations have highest amplitude in white matter and in the ventricles, respectively. In the high-TR dataset, fluctuations below 0.1 Hz are present predominantly in grey matter, and fluctuations between 0.1 and 0.25 Hz in white matter and ventricles.