SPMers,
I am trying to analyze a sparsely sampled, event-related data set which I
have not ever done. There are 3 conditions, a TR=8s, with volume acquisition
taking 2s and another 6 sec of silent gap. Am am using SPM99 to do this now.
Some questions I have:
1. I have 210 total trials across 5 scans (42 volumes per scan): Should I
correct for slice timing using a TR=8 (really an interscan interval) and TA=2
or is the slice interpolation error going to be too great with a TR of 8 sec.
2. Should I use include the HRF in the model with/without derivative?
3. I have an Excel log file with successive trials (type) (one trial per
volume) going down a column and the time stamp of presentation of stimulus in
the next column. I think the format of the matlab file is that each
condition needs its own a mat file subsequent time (TRs) are across as rows.
What is the easiest way to convert a spreadsheet such as this to something
SPM will be able to use? Maybe a Matlab.m file is not needed. I just don't
know the specifications of what SPM99 expects this or an ascii file to be.
4. I tried using SPM2 to do this but had problems at the slice_timing step
where it did not like my acquision seqence--it wouldn't advance.
I appreciate any answers to these questions
Randy Benson
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