PowerPoint Presentation - Time Series Analysis in AFNI

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Convolution Signal Model

• FMRI signal we look for in each voxel is taken to be sum of the individual trial HRFs

H Stimulus timing is assumed known (or measured)

H Resulting time series (blue curves) are called the convolution of the HRF with the stimulus timing

• Must also allow for baseline and baseline drifting

H Convolution models only the FMRI signal changes

22 s

120 s

• Real data starts at and

returns to a nonzero,

slowly drifting baseline