Hello list,

attached is my first post plus my new questions underneath every paragraph. thanks.

> >
> > 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?
>
> Doug: 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.
>
   Asaf: I'm afraid i didn't get the explanation. what is the FIR, and what
> are the the samples in it ?

> > 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?
>
>  Doug: That is right. Sorry, don't know of anything that will give you
> with-in event jitter.

     Asaf: ok, thanks. isn't it strange though? how do researches jitter the
> ISI than? manually?
>
> > 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?
>
>  Doug: Yes.
     Asaf: thanks.

hope all is clearer now,
Asaf.

From: Douglas N Greve <greve@nmr.mgh.harvard.edu>
To: Asaf Kaftory <asaf_kaftory@yahoo.com>
Cc: freesurfer@nmr.mgh.harvard.edu
Sent: Tue, October 6, 2009 6:16:37 PM
Subject: Re: [Freesurfer] optseq2 help: DPSD and jitter

I don't know what "two samples" refers to.

doug

Asaf Kaftory wrote:
> 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 <greve@nmr.mgh.harvard.edu>
> *To:* Asaf Kaftory <asaf_kaftory@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
> greve@nmr.mgh.harvard.edu <mailto:greve@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
> <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>
>
>
>
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--
Douglas N. Greve, Ph.D.
MGH-NMR Center
greve@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