Pressing the Filter button (31-5) displays the Filter popup window (Figure 32) for interactive filtering of the current time course. To filter a time course, an algorithm consisting of a sequence of equations must be specified in the Algorithm list (32-1). The first item in the list is always the current time course. Its designation ``S0'' stands for Signal at index 0. Each equation is composed of a resultant signal (i.e. time course), an operation and a set of operands. There are 12 operations available as follows:
After an Operation choice (32-3) is selected, the required operand fields are displayed. For example, for the ``Add'' operation, two source signals are required and thus the Source 1 Idx (32-4) and Source 2 Idx (32-5) fields are displayed. After the operation and operands have been specified, the Add button (32-2) inserts the filtering equation into the algorithm list. Pressing the Delete button (32-9) will remove the last item in the algorithm list. When any item in the algorithm list is selected, the resultant signal is displayed back in the Qwik plot window (31-1). The Save (32-6) and Load buttons (32-7) can be used to store and retrieve the algorithm to/from a file. The Apply Filter button (32-8) will perform the filter algorithm on the time courses of every voxel in the entire stim volume.
Figure 32: Time Course filter window.