Fig. 4.

Box plots of the percentage power deviation at the dominant frequencies. These are the differences between a) the informed dual-regressed white matter cardiac spectrum and the external pulse-ox spectrum; b) the informed and data-driven dual regressed cardiac spectra in white matter; c) the informed dual-regressed cardiac spectra in grey and white matter; d) the informed dual-regressed white matter respiratory spectrum and the external respiratory spectrum; e) the informed and data-driven dual regressed respiratory spectra in white matter; f) the informed dual-regressed respiratory spectra in grey and white matter. Box plot properties: the red line is the median, the blue box marks the $25\text{\%}-75\text{\%}$ quantiles, the whiskers span the $\pm 2.7\sigma$ range and red crosses mark outliers. P-values refer to Student's paired t-test.