Figure 2
(a) The simulated shape of the hemodynamic response (HbR in blue, HbO2 in red, and HbT in black) obtained by convolving a square wave depicting the stimulus train consisting of four sentences and the adult canonical hemodynamic response function (HRF). Default parameters for the HRF were used for HbR, and the delay of onset of the response and undershoot for HbO2 were set to −1 s relative to corresponding parameters for the HbR. The ratio of HbR and HbO2 amplitudes was set to −1:6. HbT was obtained as a sum of HbO2 and HbR. The stimulus epoch is shaded in gray and the individual stimuli indicated with a dark gray line, with habituation after the first stimulus of a train factored into the amplitude (solid lines) and no habituation (dashed ‘--’ lines). (b) Time course of HbT responses to each of the four stimulus conditions (black = neutral, orange = happy, red = angry, and blue = sad speech) in the GM voxels of the region showing activation for at least one stimulus condition. Shading indicates standard error mean (SEM). Black dashed line (‘--’) indicates the time of stimulus presentation.
