[caret-users] Re: fMRI mapping t-values

2007-06-20 Thread Katja Umla-Runge

Hi Donna,

I loaded some files up concerning my issue. They are:

EwicPics.spec
PALS_BOTH_TEMPLATE-for-MAPPING.scene
RIB_ZIF_SPMTimg_interpolated_left.metric
RIB_ZIF_SPMTimg_interpolated_right.metric
spmT_0002.hdr
spmT_0002.img
spmfig_17May2006.ps

The latter is a postscript file containing the resulting activations  
in a table. If you need some other files to check, please let me know.
I used the Average FIDUCIAL (FLIRT), LATERAL (PALS-B12_BOTH, average  
sulcal depth) scene within the tutorial file  
PALS_BOTH_TEMPLATE-for-MAPPING.scene and within the map volume(s) to  
surface(s)-process, I entered mapping atlas -- space = SPM99 and  
atlas = PALS_..._LEFT (SPM99 space) on the atlas surface selection  
window. Then I repeated this step for atlas = PALS_..._RIGHT (SPM99  
space).
I also tried multi-fiducial mapping as you suggested using  
Human.PALS_B12.LR:MULTI_FIDUCIAL_SPM99_fMRI-MAPPER.B1-B2.LEFT.73730.spec But  
again, the occipital activation cluster does not occur when I enter a  
user specified threshold of 4,66. In fact, only few and very small  
clusters remain with this threshold. The occipital cluster is in the  
left hem and has a size of 36 voxels (in the postscript-file table).  
As to spiky t-values, the ones of the significant clusters in this  
contrast only range from 4.67 to 8.19.


Thank you for your help

Katja

--
Dipl.Psych. Katja Umla-Runge

Saarland University
Department of Psychologyphone: +49 - (0)681 - 302 4643
P.O.Box 151150  fax:   +49 - (0)681 - 302 4049
D-66041 Saarbrueckenemail: [EMAIL PROTECTED]

www.BrainCog.de


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Today's Topics:

   1. fMRI mapping  t-values (Katja Umla-Runge)
   2. Re: fMRI mapping  t-values (Donna Dierker)


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Message: 1
Date: Tue, 19 Jun 2007 12:05:47 +0200
From: Katja Umla-Runge [EMAIL PROTECTED]
Subject: [caret-users] fMRI mapping  t-values
To: Caret Mailing Liste caret-users@brainvis.wustl.edu
Message-ID:
[EMAIL PROTECTED]
Content-Type: text/plain;   charset=ISO-8859-1; DelSp=Yes;
format=flowed

Dear Caret users,

Mapping spmT*.img files (SPM99) to a surface in Caret, the resulting
image seems (at first glance) to fit the data table I obtained from
SPM. However, if I set the threshold to say t = 3,61 (metric --
settings -- threshold -- Pos User = 3,61 -- threshold type: User)
which is the threshold I got from SPM for a given one-sample t-test,
less activations remain as compared to the SPM data table. As an
example, my results include an occipital activation with t = 4,67. If
I want to see this structure activated on my Caret surface, I need to
enter a threshold of about t = 1. Why do t-values and corresponding
activations do not correspond between the two systems? How can make
them correspond?
Thank you in advance.

Katja

--
Dipl.Psych. Katja Umla-Runge

Saarland University
Department of Psychologyphone: +49 - (0)681 - 302 4643
P.O.Box 151150  fax:   +49 - (0)681 - 302 4049
D-66041 Saarbrueckenemail: [EMAIL PROTECTED]

www.BrainCog.de







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Message: 2
Date: Tue, 19 Jun 2007 07:40:07 -0500
From: Donna Dierker [EMAIL PROTECTED]
Subject: Re: [caret-users] fMRI mapping  t-values
To: Caret, SureFit, and SuMS software users
caret-users@brainvis.wustl.edu
Message-ID: [EMAIL PROTECTED]
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Katja,

A couple of things come to mind:

* The 4.67 hot spot doesn't intersect the average fiducial surface.  Did
you map to the average fiducial surface, or use multi-fiducial mapping
(MFM)?  The latter method is less vulnerable to this problem.

* There could be some very large spiky values throwing off the scale.

I can take a quick look and let you know what I think:

http://pulvinar.wustl.edu/cgi-bin/upload.cgi

Is the 4.67 hot spot in the left or right hem?

Donna

On 06/19/2007 05:05 AM, Katja Umla-Runge wrote:

Dear Caret users,

Mapping spmT*.img files (SPM99) to a surface in Caret, the resulting
image seems (at first glance) to fit the data table I obtained from
SPM. However, if I set the threshold to say t = 3,61 (metric --
settings -- threshold -- Pos User = 3,61 -- threshold type: User)
which is the threshold I got from SPM for a given one-sample t-test,
less activations remain as compared to the SPM data table. As an
example, my results include an occipital activation with t = 4,67

[caret-users] Threshold cluster size

2007-06-15 Thread Katja Umla-Runge

Hello everyone,

I'm a new Caret user and am currently trying to display t-contrast  
fMRI images (SPM99) in Caret. What kind of threshold does Caret  
require (Display control -- metric -- threshold Pos)? I performed  
uncorrected t-tests in SPM with p  .001. Is 0,001 the value to  
insert? And how would you let Caret know that a threshold refers to  
correction for multiple comparisons? If you only want those voxels  
displayed that exceed a given cluster size (e.g. minimal cluster size  
= 20 adjacent voxels), how would you go about?


Thank you for your help

Katja

--
Dipl.Psych. Katja Umla-Runge

Saarland University
Department of Psychologyphone: +49 - (0)681 - 302 4643
P.O.Box 151150  fax:   +49 - (0)681 - 302 4049
D-66041 Saarbrueckenemail: [EMAIL PROTECTED]

www.BrainCog.de