[FieldTrip] EEG rereferencing with REST method

[Schoffelen, J.M. (Jan Mathijs)]

Hi Min-Young,

Did you check the original paper that is referenced in the code? I suggest to start there.

Also, re-referencing to the average is achieved by subtraction of the mean over channels, i.e. : data - mean(data)
The line you refer to is adding the mean of some variable (data_z) to data, which is not average rereferencing.

Best wishes,
Jan-Mathijs


On 21 Oct 2020, at 04:06, Min-Young Kim <mykim at kriss.re.kr<mailto:mykim at kriss.re.kr>> wrote:

Dear FieldTrippers,

I am working with 19 Ch EEG data acquired with Biosemi system. To test re-reference options, I tried average earlobes, common average, and REST methods in the preprocessing. However, I found that the EEG for REST was almost the same as the EEG for common average. When I looked at the ft_preproc_rereference.m, the line 141 says
>>data_z = G * pinv(Gar, 0.05) * data;
But then in line 144
>>data_z = data + repmat(mean(data_z), size(G,1), 1);

Isn’t the line 141 enough to generate REST EEG signals? To me, the line 144 seems to be the common average referenced EEG data. I would appreciate if someone explains the meaning of the line 144.

Thanks,
Min-Young

Min-Young Kim, Ph.D.
Tel: +82) 42 - 868 - 5204 (Office)
Email: mykim at kriss.re.kr<mailto:mykim at kriss.re.kr>
Quantum Technology Institute
Korea Research Institute of Standards and Science

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https://doi.org/10.1371/journal.pcbi.1002202

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