Hey Doug - first of all, thanks for the reply. second -
1. I'm afraid i didn't get the explanation. what is the FIR, and what does it
mean "two samples in the FIR" ?
2. ok, thanks. isn't it strange though? how do researches jitter the ISI than?
manually?
3. thanks.
________________________________
From: Doug Greve <gr...@nmr.mgh.harvard.edu>
To: Asaf Kaftory <asaf_kaft...@yahoo.com>
Cc: freesurfer@nmr.mgh.harvard.edu
Sent: Saturday, September 26, 2009 7:42:43 PM
Subject: Re: [Freesurfer] optseq2 help: DPSD and jitter
On Sat, 26 Sep 2009, Asaf Kaftory wrote:
> Hello list,
>
> I'm new to optseq, and would like your help with the following issues:
> 1. What exactly does DPSD mean? and why does the TR has to be an integer of
> it?
Delta Post-Stimulus Delay. The time between samples in the
FIR. Usually, it is just the TR. If you want to do sub-TR estimation,
you can make it less than the TR. It has to be an integer divisor of
the TR because it forms the basic "tick" of the clock.
> 2. My experiment design uses jitter - both ITI (i.e., between
> trials) and ISI (i.e., between stimulus within a compound event). As i
> understood, optseq can only supply me with the ITI jitter but no the
> ISI jitter. is that right? do you happen to know a computerized method
> to introduce a jitter within a compound event?
That is right. Sorry, don't know of anything that will give you
with-in event jitter.
> 3. Is it true that jitter in optseq is made by inserting "NULLS",
> and that the DPSD determines the "steps" of the jitter (for e.g., if
> DPSD equals 1, Nullmin equals 2 and Nullmax equals 4, the NULL events
> will be 2 3 or 4). Did i understand it right?
Yes.
doug
>
> hope to hear from you soon,
> Asaf.
>
>
>
--
Douglas N. Greve, Ph.D.
MGH-NMR Center
gr...@nmr.mgh.harvard.edu
Phone Number: 617-724-2358
Fax: 617-726-7422
In order to help us help you, please follow the steps in:
surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
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