[Eeglablist] when to re-reference

[Bin Wang]

Hello, Steve,

Thank you very much for your replying.

I used ICA implemented in EEGLAB to remove the artefact. I removed the bad
channels before ICA and interpolated them after artefact rejection. As you
said, I must interpolate bad channels before average referencing. I think
the only time to re-reference is after artefact rejection by ICA and
interpolation of bad channels, which is almost the last step of my
preprocessing. Does it sound OK?
By the way, during the recording, we put the reference electrode on left
mastoids.

Best
Bin

++++++++++++++++++++++++++++++
Bin Wang
Cognitive Neuroscience
Institute of Neuroscience and Medicine (INM-3)
Forschungszentrum Juelich,
Leo-Brandt-Str. 5
52425 Juelich
Email: b.wang at fz-juelich.de <binwang87828 at gmail.com>
        & binwang87828 at gmail.com
Telefon: 02461-61-9542
++++++++++++++++++++++++++++++

On Tue, Dec 2, 2014 at 2:51 AM, Stephen Politzer-Ahles <spa268 at nyu.edu>
wrote:

> Hello Bin,
>
> If you have bad channels that need to be interpolated, this must be done
> before average referencing (see previous messages on the list about this
> issue).
> I also suspect that referencing may need to be done before artifact
> rejection, depending on how you do artifact rejection, because some of the
> methods will be affected by your choice of reference. For example, if you
> reject based on extreme values (and apply this to all channels), you can
> imagine a situation where a given channel might not exceed the value if the
> reference is e.g. Cz but might change to exceed the value once the
> reference is changed to e.g. mastoids. Ultimately, whether or not this is
> an issue will depend on how you plan on doing artifact rejections, and
> properties of your system (e.g., whether you have bipolar EOGs that use
> their own reference separate from the rest of the electrodes).
>
> There may also be other issues that I haven't thought of here, others on
> the list may be able to clarify more.
>
> Best,
> Steve
>
>
>
> Stephen Politzer-Ahles
> New York University, Abu Dhabi
> Neuroscience of Language Lab
> http://www.nyu.edu/projects/politzer-ahles/
>
> On Sun, Nov 30, 2014 at 6:48 PM, Bin Wang <binwang87828 at gmail.com> wrote:
>
>> Dear all,
>>
>> One simple question: I would like to try several different reference
>> selections (i.e. average or mastoid), hopefully, I can find a relatively
>> better one. My question is if the re-reference step must be done before
>> epoch the data and artefact removal. Because I want to do all of
>> preprocessing steps and artefact removal, and then apply several different
>> re-reference selections, by this way I don’t need to do all of
>> preprocessing steps again. Does it sound fine? Is there any other artefacts
>> or problems that will be induced by the re-reference of last step.
>>
>> I am looking forward your any advices
>>
>> Thank you in advance,
>>
>> Bin
>>
>> ++++++++++++++++++++++++++++++
>> Bin Wang
>> Cognitive Neuroscience
>> Institute of Neuroscience and Medicine (INM-3)
>> Forschungszentrum Juelich,
>> Leo-Brandt-Str. 5
>> 52425 Juelich
>> Email: b.wang at fz-juelich.de
>> <https://webmail.fz-juelich.de/owa/redir.aspx?C=hswxAlx8wU6cP189jFS_1w0PFSKb8dAIIkV6dqtR-VUUMNMIisKisV7RZADeuZK3wPR2w27Q5yU.&URL=mailto%3abinwang87828%40gmail.com>
>>      &  binwang87828 at gmail.com
>> <https://webmail.fz-juelich.de/owa/redir.aspx?C=hswxAlx8wU6cP189jFS_1w0PFSKb8dAIIkV6dqtR-VUUMNMIisKisV7RZADeuZK3wPR2w27Q5yU.&URL=mailto%3abinwang87828%40gmail.com>
>>
>> <https://webmail.fz-juelich.de/owa/redir.aspx?C=hswxAlx8wU6cP189jFS_1w0PFSKb8dAIIkV6dqtR-VUUMNMIisKisV7RZADeuZK3wPR2w27Q5yU.&URL=mailto%3abinwang87828%40gmail.com>
>> Telefon: 02461-61-9542
>> ++++++++++++++++++++++++++++++
>>
>>
>>
>>
>>
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