The paradigm file is a simple text file that describes which stimulus was present when. You will need a separate paradigm file for each run/series in the visit. It contains at least 2 columns and may contain as many as 4. The fist column is the onset time of the a stimulus relative to the acquisition of the first STORED image in the series (ie, not including discarded acquisitions or dummy scans). The second column is a numeric ID that codes condition/event type that was presented at that time. The (optional) third column is the stimulus duration (redundant with column 1). The (optional) fourth column is a name of the condition/event type (redundant with column 2). An example of a paradim file is given below: BR
0.0000 2 3.000 Neutral-Long BR 3.0000 3 3.000 Fearful-Short BR 6.0000 0 1.000 NULL BR 7.0000 4 3.000 Fearful-Long BR
10.0000 0 2.000 NULL BR 12.0000 1 3.000 Neutral-Short BR 15.0000 0 3.000 NULL BR 18.0000 2 3.000 Neutral-Long BR
BR There are 5 event types, 4 task-related and 1 fixation (NULL). The Null/Fixation condition is ALWAYS 0. The rest of the conditions must be numbered sequentially starting at 1. These condition codes will be used later in fsfast when constructing contrasts. FSFAST only pays attention to the first 2 columns; the rest are for making them easier to read. The onset time does not need to be a multiple of the TR or linked in any way (eg, the onset time could be something like 11.340). There are a few cases where you might need to re-code the paradigm file to indicate how long the stimulus lasts, but these are rare.