FIG. 1.

Illustration of WB-LNR. (a) WB-LNR can introduce additional variance into the HF band of fMRI time series. Here, measurement y and nuisance regressor x both have low (0.04 Hz) and high (0.4 Hz)-frequency components. The cleaned signal ɛ [from Eqn. (3)] on the bottom includes a large HF contamination introduced by WB-LNR from the LF component. (b) Introduced variance as a function of the ratio k of LF and HF fluctuation amplitudes. (c) Illustration of how RSFC at low frequencies is twisted and passed to the HF band of fMRI data through WB-LNR. See text description in the Artificial network patterns introduced in HF bands section. fMRI, functional magnetic resonance imaging; HF, high-frequency; LF, low-frequency; LNR, linear nuisance regression; RSFC, resting-state functional connectivity; WB, whole-band. Color images available online at www.liebertpub.com/brain