Hello,
Our lab is currently in the midst of trying a faster fMRI acquisition with a short TR = 500 msec. I'm thinking that with much shorter TR, the signal/noise behaviour will change as well, in particular, the way the residual autocorrelation should be treated. This is related to whether or not my FEAT post-stats outputs are reliable. I'm stuck at this point after running the FSL FEAT and see the result. My questions:
1. Can I still use Tukey estimation for autocorr. estimate in film_gls? I'm just wondering whether using AR model with higher order may work better for shorter TR.
2. In the 2001 paper (Woolrich, et.al.), the Tukey formula M = 2* sqrt(N) but after looking at the FSL code, M = 2*sqrt(N)/2 which is just sqrt(N). Does this matter much? Sorry I'm not from signal processing background.
Thank you very much!!
warm regards..
sidarta
|