Dear FSL users,
I'm new to using FEAT and I have a question concerning parametric modulation.
My subjects perform a mental rotation task according to 4 rotation angles (45°, 90°, 135°, 180°). I’m assuming that the BOLD-response goes up with higher rotation angles, seeing as the RTs increase linearly with rotation angle.
What would be the best way to model this parametric modulation?
1) Using a separate EV for each rotation angle and then specifying a contrast -2 -1 1 2
2) Using one EV for all rotation angles, and entering the RT in the 3rd column.
If so, should I demean the RTs?
3) Using one EV for all rotation angles, and entering 1,2,3 or 4 in the 3rd column
4) Using one EV for all rotation angles, and entering -2, -1, 1 or 2 in the 3rd column
Thanks for the info.
Kind regards,
Annouchka
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