[Eeglablist] 50 Hz Removal

[Fabio Castro]

Hello,

I am conducting an experiment where participants imagine a movement, and I am collecting eeg data to analyse the event-related desynchronisation. I had a couple of participants' data that look a bit weird when uploaded on EEGLAB. (v. 14.1.1). Data was collected using an ANT eego sport system, and it was recorded online with reference to CPz, but was re-referenced offline to the average of the two mastoid electrodes. Data was uploaded on EEGLAB using the ANT extension (.cnt format).
The data has also been band-pass filtered 2-45 Hz, but the signal looks different from the one I collected. I also checked if the original file had this same problem (the non-re-referenced one), and yes, it has the same problem. I have uploaded the same file (same extension), in brainstorm, another Matlab toolbox for EEG analysis, and the signal looks completely different.
I also have run the power spectrum analysis on both software, and I looks that in EEGLAB, even though I band-pass filter 2-45 Hz, it does not remove the 50Hz. On the contrary, in Brainstorm it does remove it.
Do you know what may be the problem here, and why the 50 Hz are not removed?

Kind Regards

FABIO

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