[Eeglablist] Preprocessing steps before Time Frecuency Analysis

[Ruben Perellón Alfonso]

Hello!

I am about to pre-proces data before doing Morlet Wavelet Transform.
Some trials where already rejected based on visual rejection criteria and
bad channels where also identified via visual inspection..
These are the next planned steps:

1. Re-reference data to linked Mastoids (TP9, TP10)
2..Interpolate bad channels.
3. Reject epochs based on threshold -+500microV
4. Reject epochs based on improbable events, 6SD per channel 2SD for all
channels.
5. Do wavelet transform

I would really appreciate the input regarding how correct the order of this
steps looks to you, and whether you consider some fundamental step is
missing.

I also have a concrete question regarding step 1:
We recorded using a 128 channels Brain Producs system, with a common
reference at FCz. This reference does not appear on import of data into
EEGLAB of course. Now I am wondering how to properly re-reference the data.
In the EEGLAB wiki it says that for linked mastoids, one should first
create a dummy channel of zeros for the common reference, then do average
reference keeping the common reference, and only then re-reference again to
the mastoids. But why can't I just directly re-reference to mastoids? Once
re-reference is done, is there any reasons why I should keep the reference
channels in the data?

Thanks
Ruben
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