PowerPoint Presentation - Using AFNI Interactively

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Expressing HRF via Regression Unknowns

• The tool for expressing an unknown function as a finite set of numbers that can be fit via linear regression is an expansion in basis functions

H The basis functions yq(t ) are known, as is the expansion order p

H The unknowns to be found (in each voxel) comprises the set of weights bq for each yq(t )

• Since b weights appear only by multiplying known values, and HRF only appears by in final signal model by linear convolution, resulting signal model is still solvable by linear regression