AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Gang Chen
May 11, 2006 10:14AM
> If I convert my time series to % signal change (a(t)/mean(a)*100)
> will the values of the regression coefficents returned by
> 3dDeconvolve reflect % signal change values?

Yes, usually you can interpret those regression coefficients as percent signal change if the regressors are scaled properly.

> If I did not scale the data prior to 3dDeconvolve how could I obtain
> % signal change values from the regression coefficents?

If there is only one run of data, you can estimate % signal change by dividing those regression coefficients by the baseline coefficients at each voxel. However with multiple runs of data unscaled, regression analysis with combined data could be problematic because of baseline variation across runs.

> I have several non-linear drifts due to a long run and irregularities
> in scanner function. Should I attempt to correct these drifts using
> a high pass filter implemented using 3dFourier or can I detrend
> the time series within 3dDeconvolve itself?

Either is probably fine although detrending in 3dDeconvolve is preferred. Or you can include those frequencies as regressors in 3dDeconvovle.

Gang
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Subject Author Posted

Three 3dDeconvolve questions?

Vincent Costa May 10, 2006 11:59PM

Re: Three 3dDeconvolve questions?

Gang Chen May 11, 2006 10:14AM

Re: Three 3dDeconvolve questions?

Vincent Costa May 12, 2006 11:50AM

Re: Three 3dDeconvolve questions?

Gang Chen May 12, 2006 05:17PM

Re: Three 3dDeconvolve questions?

Vincent Costa May 12, 2006 06:18PM

Re: Three 3dDeconvolve questions?

Gang Chen May 12, 2006 06:31PM