Katie

On Fri, Apr 15, 2011 at 2:51 PM, Douglas N Greve <greve@nmr.mgh.harvard.edu> wrote:

Oh, sorry, I had forgotten when I introduced the 4col format. Yes, 4.5 does take the 4 col. I actually dont remember exactly what 4.5 does when you give it autostimdur with a 4col. It might ignore the duration in the parfile and compute it from the stimulus timing. If you represent all time in your paradigm file, this should do the same thing. For the FIR, the stimulus duration is ignored entirely.

doug

Katie Bettencourt wrote:

Wait, I'm confused, in v 4.5 (which I'm using) the paradigm files have 4 values per line (starting time, condition, length, and weight), so don't they have the lengths in there? I know you could use an older paradigm file with only 2 columns (starting time, condition), and in this case I would list each TR and the condition there, but the wiki says that v. 4.5 can use the 4 column paradigm files. Is that not true? I mean it obviously uses the weights....

I ran an event related analysis with -noautostimdur in the analysis, with a 4 column paradigm file. I did not list every TR, but used the 3rd column to list the length of time. I got what appears to be valid data out. When I redid it with -autostimdur, I got very little activation. But if the -noautostimdur assumes that each event is equal to the TR (which is shorter than the actual durations I have), then wouldn't the analysis have had problems because I didn't cover all the TRs in the paradigm file? But it worked fine.

I'm very confused here.

Also, is there a difference between the way this is used in FIR and Gamma analyses?

Katie

On Fri, Apr 15, 2011 at 2:33 PM, Douglas N Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> wrote:

FYI: autostimdur is not valid in version 5.X because the stimulus
duration is supplied in the paradigm file. For earlier versions,
there was no info in the par file about the duration. The
-autostimdur will compute the duration of the stimulus from the
paradigm file based upon the time to the next stimulus entry this
works as long as all time is accounted for in the parfile and no
stimuli overlap. If you use -no-autostimdur, then it will assume
that the duration of the event is equal to the TR.

doug

Katie Bettencourt wrote:

I'm a bit confused about what the -autostimdur and
-noautostimdur flags in mkanalysis-sess do. I've checked the
help files, but the wording is a bit confusing, and when I run
them on my event related design, I get different results
depending on which flag I use, with the -noautostimdur being
more of what I expect as far as results go.

Also, they are only used in event related and AB designs, not
blocked, correct?

Katie

-- Douglas N. Greve, Ph.D.
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