Yes, those activations were located within the basal ganglia ... and it
does not make a lot of sense (at least if it is the only activation that
'survived'). I also ran these analyses in a larger sample (22 subjects).
The first versus second level discrepancy also occured. The
normalization seemed to be ok. Nevertheless, we also applied a
non-linear normalization, but the 'unusual' results remained. I'll check
the amount of movement again.
I attached some of the results again. I think the first file was to
large for the mailing list.
Thanks again,
Kirsten


---------------------------------------------------------
Dr. Kirsten Labudda, Dipl.-Psych.

Krankenhaus Mara 

MRT-Abteilung 
Tel.: 0521-772 777 61 
& 
Station für Psychosomatische Epileptologie 
Tel.: 0521-772 789 22 
---------------------------------------------------------

>>> Chris Watson <[log in to unmask]> 7.11.2012
17:46 >>>
Is that bilateral thalamic and caudate activation? Is that something 
that makes sense for your experiment?
I think what you're seeing *could* be due to only having 9 subjects; 
however, if you see the standard L frontal activation in most/all of 
them, then I don't know what might be causing the discrepancy. Is there

an especially high amount of motion in these subjects? Does the 
normalization look right?


On 11/07/2012 11:46 AM, Kirsten Labudda wrote:
> Dear Chris,
> thanks for your quick response. I attached the screenshots of both
> first and second level analyses versions I conducted (version 1:
only
> the activation condition was modelled; version 2: activation and
rest
> was modelled on the first level) in the small group. I used the
movement
> parameters as regressors in the first level analysis. The second
level
> results are thersholded at p<.001 as only very few voxel survived
the
> thershold of p<.05 FWE corrected on the second level.
> Thanks for your help!
> Kirsten
>
> ---------------------------------------------------------
> Dr. Kirsten Labudda, Dipl.-Psych.
>
> Krankenhaus Mara
>
> MRT-Abteilung
> Tel.: 0521-772 777 61
> &
> Station für Psychosomatische Epileptologie
> Tel.: 0521-772 789 22
> ---------------------------------------------------------
>
>>>> Chris Watson<[log in to unmask]>  7.11.2012
> 16:38>>>
> Can you post screenshots of your design matrix, the results of 1st
and
>
> 2nd-level analyses, etc?
>
> Regarding your design: you only need one regressor, for the task. A
> contrast of "1" will reflect "task>  rest".
> You also might want to exclude the movement parameters, if your
> experiment is a block design. Check what the literature says on that
> matter.
>
>
> On 11/07/2012 09:46 AM, Kirsten wrote:
>> Dear fMRI-experts,
>> we wonder about conflicting results of the first and second level
> analysis we conducted with our fMRI data. We used a simple blocked
> verbal fluency task with one activation condition (verbal fluency,
10
> blocks) and a rest condition (also 10 blocks). I wonder, whether we
did
> something wrong when using SPM (we used SPM8 and 5 and have the
problem
> with both versions). That’s what we did: After preprocessing
> (realignment, normalization, smoothing), we conducted a first level
> analysis specifying the verbal fluency blocks as activation condition
in
> each subject (by entering the onset scans of each block and its
duration
> in terms of scans) and used the movement parameters as individual
> regressors. We defined two contrasts (verbal fluency: 1 and rest:
-1).
> Is it ok not to model the resting condition separately? We thought so
as
> our design only includes two conditions and with that the vector 1
> automatically contains the information activation>   rest, right?
> Nevertheless, I also conducted the first level analysis with the two
> conditions modeled separately using two T-contrasts then (verbal
> fluency>   rest: 1 -1 and rest>verbal fluency -1 1). Both first
level
> procedures lead to very similar results reflecting typical cortical
> language activations.
>> I then used the contrast images (the activation condition>rest,
again
> of both first level procedures described above) in the second level
> analysis to run a one-sample t-test with the contrasts: activation>
> rest: 1 and rest>activation: -1. Surprisingly, the typical cortical
> language activation from the first level analysis completely
> disappeared. Instead, only subcortical activation remained (that was
> present in the first level analysis, too, but it was much weaker
than
> the typical language activation).
>> We have the problem of very incongruent first and second level
> results with SPM5 and 8 and within two different patient groups (one
was
> small having 8 subjects only, but the other group includes 22
> subjects).
>> Does anybody have an idea why the first and second level results
are
> so divergent? Did we simply do something wrong in SPM?
>> Thanks in advance,
>> Kirsten
>>
>
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