[Eeglablist] Compatability and artifact identification issues

[Achim, André]

One problem to expect with ECG monitored at a different site (over the neck or below) is that the electro-cardiac signal will take a different form for different body positions. Subtracting a multiple of this external signal from the EMG signal should only partly cancel the ECG contribution. One solution to consider is to use the external ECG signal as a synchronizing signal and to compute the average ECG contribution at your EMG signal and then subtract it, synchronized to the external ECG, from the EMG.

André Achim

-----Message d'origine-----
De : eeglablist-bounces at sccn.ucsd.edu [mailto:eeglablist-bounces at sccn.ucsd.edu] De la part de Johan
Envoyé : 1 décembre 2009 12:47
À : Klados Manousos
Cc : eeglablist at sccn.ucsd.edu; Power elf,Jordan
Objet : Re: [Eeglablist] Compatability and artifact identification issues

Hello!

I, too, am looking for something that can remove artifacts from the
EMG. In particular I want to remove ECG artifacts from the (surface)
EMG recorded from muscles in the neck. This ECG artifact is
particularly nasty when you try to calculate EMG-EMG coherence
spectra. High-pass filtering alone won't cut it to succesfully remove
the ECG artifact.

The AAR1.3 has some functionality to remove EOG artifacts from EEG,
but makes no mention what to do to/how to proceed to remove ECG from
surface EMG. I do have a separately recorded ECG signal.

Is there anything you could recommend?

Regards,

Johan van der Meer, PhD Stud.
Academic Medical Centre, Amsterdam





On Mon, Oct 12, 2009 at 6:37 PM, Klados Manousos <mklados at gmail.com> wrote:
> Dear Jordan
>
> Automatic Artifact Rejection (AAR) Plugin for EEGLAB is availiable in the
> EEGLAB's site. As i quickly see in the paper mentioned above they use LMS
> algorithm for the implementation of the adaptive filters. AAR includes LMS
> algorithm so you can use it (or mode it as you like...for the cascading).
> Except LMS AAR includes another 4 (i thing) regression-based algorithms for
> artifact rejection. According to my analysis and my opinion (which is going
> to be published soon) among the regression techinques Schlogl's algorithm
> (Schlogl,2007) seem to have better performance. This aglorithm doesn't
> included in the AAR but it is very easy in it implementation. I have to
> mention that Schlogl algorithm uses one step for the computation of
> propagation coefficients and not an iterative procedure as adatpive filters.
> If you still want to use an adaptive filter included in the AAR i propose
> you to use LMS. Comparison's results (Klados,2008) suggest that LMS performs
> well in EEG data.
>
>
> Schlogl, C. Keinrath, D. Zimmermann, R. Scherer, R. Leeb, G. Pfurtscheller,
> “A fully automated correction method of EOG artifacts in EEG recordings” ,
> Clinical Neurophysiology 118 (2007) 98–104.
> Ghirnikar, A.   Alexander, S.T. Stable recursive least squares filtering
> using an inverse QR decomposition. IEEE International Conference on
> Acoustics, Speech and Signal Processing 1990 ICASSP-90, 1990; 3 : 1623-1626
> M.A.Klados, C. Papadelis, C.D. Lithari and P.D. Bamidis. The Removal Of
> Ocular Artifacts From EEG Signals: A Comparison of Performances For
> Different Methods, J. Vander Sloten, P. Verdonck, M. Nyssen, J. Haueisen
> (Eds.): ECIFMBE 2008, IFMBE Proceedings 22, pp. 1259–1263, 2008
>
>
> 2009/10/8 Power elf, Jordan <J.PowerElf2 at nuigalway.ie>
>>
>> Compatibility and artifact attenuation issues
>>
>> Dear EEGLAB members,
>>
>> I am currently conducting an electroencephalography experiment with the
>> neuroscience division of the National University of Ireland Galway. During
>> the experimental design phase I encountered much discussion about the
>> algorithms used to attenuate artifact interference in the EEG signal. Many
>> papers seem to agree that the only means of accounting for ECG and EOG
>> artifacts is to record these signals simultaneously on a different channel.
>> Once the data is collected it can then be processed using filtering methods.
>> These papers (such as "Artifact removal from EEG signals using adaptive
>> filters in cascade") include many advanced algorithms to account for these
>> artifacts once all the data has been recorded. Unfortunately the sheer scale
>> of my experiment makes the manual processing of my data a prohibitive
>> prospect. I was wondering if EEGlab included a facility that applied these
>> adaptive filter algorithms automatically when presented with the raw eeg
>> data and the EKG and EOG artifacts. I would also like to know if eeglab is
>> compatible with labchart, the program i am using to record my data.
>>
>>
>> Any help you could provide would be greatly appreciated,
>> Jordan
>>
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>
>
> --
> Klados A. Manousos
> Graduate Student, Research Assistant
> Group of Applied Neurosciences
> Lab of Medical Informatics, Medical School
> Aristotle University of Thessaloniki
> Thessaloniki, Greece
> _________________________________________________
> Tel: +30-2310-999332
> Website: http://lomiweb.med.auth.gr/gan/mklados
>
>
>
>
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