[FieldTrip] Problem with re-referencing of fNIRS data

[Kamil Hiralal]

Dear community,

My name is Kamil Hiralal and I am a PhD student at the Erasmus Medical Center in Rotterdam.
I am currently trying to analyze previously collected fNIRS data from a study investigating phenotypical overlap between children with autism spectrum disorder and Fragile X syndrome.

We have measured fNIRS signal using an Artinis device with a custom channel template with 8 channels of interest placed over the left and right frontal hemispheres. For both the left and right hemisphere, we have also used a short channel as reference.
I am currently trying to re-reference our normal distance channels based on the short channels, but I am having some trouble and was hoping somebody could help me out.

When I am trying to run the ft_nirs_referencechannelsubtraction() function, I get the following error:


Unable to perform assignment because the left and right sides have a different number of elements.

 Error in ft_nirs_optodedistance (line 89)

  optodedistance(posIdx)              = sqrt( (xf(idxR)-xf(idxT)).^2+(yf(idxR)-yf(idxT)).^2 ); % Pythagorean theorem

Error in ft_nirs_referencechannelsubtraction (line 123)

distances   = ft_nirs_optodedistance(datain);
I am using the default cfg set-up (shortdistance = 1.5, closedistance = 15, method = 'QR', verbose = FALSE). I am also using raw NIRS data, as outputted by FT_PREPROCESSING. I hope anyone might be able to help me with this question!

Best,
Kamil Hiralal
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