Default data created by Define Datamode -->SaveAs OLay

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AFNI version info (afni -ver): AFNI version info (afni -ver): uname -a Linux DESKTOP-RJJ49UB 4.4.0-19041-Microsoft #3996-Microsoft Thu Jan 18 16:36:00 PST 2024 x86_64 x86_64 x86_64 GNU/Linux afni -ver Precompiled binary linux_ubuntu_16_64: Apr 5 2024 (Version AFNI_24.1.01 'Publius Septimius Geta')

Quick question:

When using Define Datamode SaveAs OLay (after using FIM -> compute FIM -> FICO)

When I load the niftii data in python using the nibabel nilearn libraries, as such, I notice that there are 5 dimensions in the Nifti1Image and numpy.memmap created. :

overlay_img = nib.load('mydata/location/fMRIdata_overlay.nii')

overlay_data = overlay_img.get_fdata()

This is what the data looks like using df.shape:

Overlay: (46, 55, 43, 1, 2)

I get that the first three dimensions are X, Y and Z, and the fourth dimension is time.

What is the exact output being saved in dimension 5 when using default settings? I only have indices 0 and 1 in dimension 5. They both look like statistical values, but appear distinct from each other.

What types of values does each index contain? How are they different or related? Can we change what we are saving? If so, is it even recommended or useful to do so?

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Hi Sandra,

When computing the FICO dataset and then setting it as the Overlay , the 2 volume labels should be seen (and selectable, under Define Overlay) as OLay and Thr volumes, with #0 being the "Fit Coef" (i.e. the magnitude of the regressor fit to the data) and the "Correlation".
Running "3dinfo" on the saved dataset should also show the labels and their statistical parameters.

Does that seem reasonable?

  • rick