[Eeglablist] ASR – include EOG/ECG channels, apply before referencing?

[Makoto Miyakoshi]

Dear Kevin,

> Should I remove DC mean before running ASR?

Yes.
That is why the high-pass filter process is positioned at the first step in
the clean_rawdata(). If DC and slow wave (< 1.0 Hz) are not removed, ASR
does not work well.

Makoto

On Tue, May 5, 2015 at 6:14 PM, Kevin Tan <kevintan at cmu.edu> wrote:

> Thanks so much for the response! Much appreciated.
>
> I have another question: the BioSemi runs off a battery; "DC mean" has to
> be removed until the EEG signal looks normal.
>
> Should I remove DC mean before running ASR? Seems to make a difference in
> terms of # of blocks ASR cleans.
>
> Cheers,
> Kevin
>
> --
> Kevin Alastair M. Tan
> Lab Manager/Research Assistant
> Department of Psychology & Center for the Neural Basis of Cognition
> Carnegie Mellon University
>
> Baker Hall 434
> <https://www.google.com/maps/place/40%C2%B026%2729.5%22N+79%C2%B056%2744.0%22W/@40.4414869,-79.9455701,61m/data=!3m1!1e3!4m2!3m1!1s0x0:0x0>
>  | kevintan at cmu.edu | tarrlab.org/kevintan
> <http://tarrlabwiki.cnbc.cmu.edu/index.php/KevinTan>
>
> On Tue, May 5, 2015 at 1:43 PM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>
> wrote:
>
>> Dear Kevin,
>>
>> > I'm wondering whether to include EOG and ECG channels in ASR like in
>> traditional ICA? Also, whether to apply ASR before referencing?
>>
>> Yes, for the purpose of consistency. If I understand correctly (I say
>> this because the main algorithm is totally Christian's, and I just wrote a
>> wrapper) ASR computes correlation matrix of the channels. You may want to
>> include all channels rather than separate some of them (unless you reject
>> them permanently). Applying it before rereferencing makes sense, since you
>> want to clean the data (i.e. exclude noisy channels) before referencing.
>>
>> Your pipeline looks fine to me. Good luck!
>>
>> Makoto
>>
>> On Fri, May 1, 2015 at 1:36 PM, Kevin Tan <kevintan at cmu.edu> wrote:
>>
>>> Hello Dr. Miyakoshi & EEGlab list members,
>>>
>>> I'm exploring artifact subspace reconstruction (clean_rawdata plugin)
>>> as an alternative to threshold-based artifact rejection.
>>>
>>> I'm wondering whether to include EOG and ECG channels in ASR like in
>>> traditional ICA? Also, whether to apply ASR before referencing?
>>>
>>> I am using a 128-channel BioSemi ActiveTwo with 8 external channels: M1,
>>> M2, bipolar hEOG, bipolar left vEOG, bottom right vEOG, and ECG.
>>>
>>> BioSemi always records unreferenced. I recorded at 512hz for the sake of
>>> comp resources.
>>>
>>> Here's my preliminary preproc pipeline:
>>>
>>>    1. Import data using BDF plugin (unreferenced)
>>>    2. Add channel location info
>>>    3. CleanLine
>>>    4. ASR (including EOG/ECG?)
>>>    5. Reference to 128ch scalp average
>>>    6. ERPlab:
>>>    1. Create Eventlist
>>>       2. Extract event-based epochs
>>>       3. Create averaged ERPs
>>>       4. Lo-pass @ 30hz
>>>
>>> Any advice would be appreciated :-)
>>>
>>> Many thanks,
>>> Kevin
>>> --
>>> Kevin Alastair M. Tan
>>> Lab Manager/Research Assistant
>>> Department of Psychology & Center for the Neural Basis of Cognition
>>> Carnegie Mellon University
>>>
>>> Baker Hall 434
>>> <https://www.google.com/maps/place/40%C2%B026%2729.5%22N+79%C2%B056%2744.0%22W/@40.4414869,-79.9455701,61m/data=!3m1!1e3!4m2!3m1!1s0x0:0x0>
>>>  | kevintan at cmu.edu | tarrlab.org/kevintan
>>> <http://tarrlabwiki.cnbc.cmu.edu/index.php/KevinTan>
>>>
>>
>>
>>
>> --
>> Makoto Miyakoshi
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, University of California San Diego
>>
>
>


-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20150507/d1aa615b/attachment.html>