FIGURE 3.

Schematic chart of our ERS/D-based PPI analysis. In this technique, the hemodynamic response (explained variable X_i) in a region i is estimated as a superposition of impulse responses. The regression coefficient is calculated so that the error (e) between the estimated hemodynamic response (X_i) and the observed hemodynamic response is minimized. This analysis can be interpreted as estimating the area where the contribution from a certain ERS/D is increased by an event (psychological or experimental factor).