Hi - so you extracted the mean timecourse over a (e.g.) hand-drawn ROI
using Featquery - sounds fine. And then you used this as a regressor
when going back and analysing the _same_ resting dataset? That should
work ok.
Cheers.
On 4 Feb 2008, at 16:16, Dost Ongur wrote:
> Hi Steve,
>
> I did turn off the HRF convolution in the FEAT run. I also did not
> use
> derivatives, and no low pass filter. Also, I tried the FEAT with and
> without the high pass filter, and got the same worrisome results.
>
> One thought: the timecourse of the seed region was generated with
> Featquery
> from a resting state scan, so there was no meaningful PEs etc in the
> design, just a "dummy" one. All I did is extract the
> mean_mask_ts.txt.
> Would that make a difference for how the timecourse is calculated?
>
> Dost
>
>
>
> On Mon, 4 Feb 2008 13:34:17 +0000, Steve Smith
> <[log in to unmask]> wrote:
>
>> Hi Dost,
>>
>> If you're putting a seed voxel's timecourse back in as a regressor of
>> the same data, you should definitely see that voxel (and probably
>> neighbouring ones) as highly 'activated' - so it does sound like
>> there's a problem here. Is it possible that you forgot to turn off
>> the
>> HRF convolution for the final FEAT run? The voxel-extracted
>> timecourse
>> already contains the HRF convolution.
>>
>> Cheers.
>>
>>
>> On 1 Feb 2008, at 19:44, Dost Ongur wrote:
>>
>>> We have recently started to perform whole brain signal correlations,
>>> to test
>>> hypotheses about resting state circuits based on our ICA. Our first
>>> such
>>> test used the LMFG portion of area 46 as the seed ROI, and we
>>> noticed that
>>> neither patients nor controls yielded significantly correlated
>>> voxels in
>>> left sided area 46 itself. Does FEAT know to exclude the seed ROI
>>> in some
>>> fashion, or are we simply looking at poor auto-correlation within
>>> the ROI?
>>>
>>
>>
>> ---------------------------------------------------------------------------
>> Stephen M. Smith, Professor of Biomedical Engineering
>> Associate Director, Oxford University FMRIB Centre
>>
>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>> +44 (0) 1865 222726 (fax 222717)
>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>> ---------------------------------------------------------------------------
>> =
>> =
>> =
>> =
>> =====================================================================
>
---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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