Writing covariable-corrected images

Submitted by alex on Sat, 07/11/2009 - 23:43

 Hi again,

I am trying to use the rest_Y_RegressOutCovariables function to write our covariable-corrected image files. I get the error below, which I was hoping you could help me with. I've double-checked, and the timeseries vectors are the correct length.
Thanks for your help,
Alex

 

 

Regressing Out Covariables:

 

     Read 3D EPI functional images: "/work/imaging8/af397/rest_analysis/vols/filtered/1002593_filtered".........................................................................................................................................................................

??? Error using ==> eq

Matrix dimensions must agree.

 

Error in ==> rest_writefile at 81

    if (dtype=='single')

 

Error in ==> rest_Y_RegressOutCovariables at 70

    rest_writefile(AllVolume(:, :, :, x), ...

Submitted by YAN Chao-Gan on Mon, 07/13/2009 - 23:21

Thank you for your report!
Please re-write the code:
if (dtype=='single')

to

if strcmp(dtype,'single')

I have made a multimedia course of DPARSF, you can get more information from it. I will upload it tomorrow.

Submitted by alex on Tue, 07/14/2009 - 04:16

 Great - that seems to have done the trick!

I just had a question about the detrending and filtering. I have been looking at ROI time courses at various stages of detrending and filtering.
I have noticed that after detrending, the linear trend does indeed seem to be removed, as is expected.
After filtering (.008 to .08 Hz) only (without detrending), I can clearly see the slower oscillations, although the linear trend is still present, as would be expected.
However, after detrending + filtering, the oscillations become very regular, and the time course has a strong linear trend.

This seems strange to me. Does the trend get added back into the time course during filtering? Does this sound normal?

Thanks again for your help,
Alex 

Submitted by YAN Chao-Gan on Wed, 07/15/2009 - 13:00

I just remember Xiao-Wei said this procedure is used to keep the same results as AFNI.
I am sorry I do not know more detailed reason.
Could Xiao-Wei, Xiang-Yu, Xi-Nian and Prof. Zang give more deep comments please?