FIGURE 6.

Spatial distribution of the timing of cardiac aligned responses in the cranium across the group. For each voxel in each subject, we calculated the peak time of the cardiac aligned response in terms of the cardiac cycle with the peak of the photoplethysmography (PPG) at time zero. These timing maps were aligned in MNI152 space; in this way, the average timing across the subjects could be calculated. (a) The timing of the local minima for all voxels that had an average R ² > 30 across the subjects. Red colors indicate times before the PPG peak and blue colors indicate times after the PPG peak. (b) The timing of the local maxima for all voxels that had an average R ² > 30 across the subjects. Purple colors indicate times before the PPG peak and cyan colors indicate times after the PPG peak