Figure 3.

How we used observed alpha-dependent fMRI baseline modulations to predict high alpha-state fMRI baseline modulations. A, Ongoing alpha power (condition II). B, Regressor IIc (i.e., ongoing alpha power convolved with the canonical HRF+ derivatives, orthogonalized to Regressors IIa and IIb) is fitted to the data to estimate beta magnitudes. C, Prestimulus alpha power increase found in the high alpha condition relative to control condition (Fig. 2C). D, Estimation of the alpha-rhythm power impulse-response function by scaling HRF+ derivatives with the beta values obtained in B. With the generic hemodynamic impulse response function, we can predict an fMRI response to any arbitrary alpha-power behavior. E, We predicted fMRI responses to prestimulus high alpha-rhythm power signals by convolving the curves depicted in C and D. Resulting predictions were compared with the observed high alpha fMRI stimulus-response modulations (Fig. 6, blue and red curves).