Estimating the IRF


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Posted by Lukas Pezawas on November 19, 2002 at 11:11:17:

Hi AFNI experts!

We are conducting a mixed trial (several pure event related "block" with a baseline period in between, 2 runs of 183 volumes, TR=3000msec; the stimulus is on for 1500 msec=1/2 TR)

We used waver to create the reference function with a command similar like this:

waver -GAM -dt 3.0 -tstim `cat timevector.1D` -numout 183 > waverfile.1D

As far as I understand, this reference function might be not the best reference for our actual data since the stimuli are presented in an event related manner...
I am looking for a way in AFNI, how I can get an impression based on the real data what the real IRF is looking like in regions we are interested in in order to specify waver in a more accurate way.

I did not find too much about that in the message board or in the AFNI documetation.
I am also not sure, if the data generated by the -iresp option in 3dDeconvolve would be of any value or 3ddelay (and how I can extract the delay value..)

Any suggestion would be appreciated...


Thanks,


Lukas



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