Figure 3.

Scheme of wavelet coherence analysis (see Section Wavelet Coherence Analysis for details). In the first step fNIRS and physiological signals are wavelet transformed to provide wavelet scalograms WCT_{HbO, HbR} and WCT_phys. The coherence between these scalograms yields a scale dependent wavelet coherence. Frequency bands corresponding to the maximum of the wavelet coherence and the coherence phase at maximum are determined. These parameters are further used to create auxiliary physiological regressors in the GLM de-noising (see Section General Linear Modeling and Physiological De-noising and Figure 4).