The program 'vimagetimecourse' caluclates an average time course for each voxel. Inputs are preprocessed raw data. Length and resolution of the time course can be predefined. Output files contain time courses for each voxel inside the brain. Output files can be handled like raw data. In particular, visualization is possible using the option -raw within 'vlview':
Example output:
Average time courses can be subtracted from each other using
'vdifftimecourse'. In this program, the second average
timecourse (parameter ' -second') is subtracted from the first
(parameter '-first'). This is useful, in particular,
for subtracting null events from another condition.
Average time courses as produced by 'vimagetimecourse' and 'vdifftimecourse' can be further processed using the program 'vextractparam'. This program caluclates characteristic parameters of average time courses. They include 'amplitude', 'slope', 'dispersion', and four time points depicted in the figure below:
Important! Extracted parameters can only be meaningfully interpreted, if the underlying BOLD signal resembles (roughly) that of an activation as depicted above. The result images of 'vextractparam' should therefore be masked by a z-map or contrast image including only significantly activated voxels. This can be done with the program 'vimagemask'.