ECG artifacts in MEG

Robert Oostenveld r.oostenveld at FCDONDERS.RU.NL
Thu Feb 12 18:02:05 CET 2009


Dear Andrej

We initially (i.e. relatively early in fieldtrip development and in
developing our MEG analysis skills) have attempted to remove the ECG
artifact by QRS detection, averaging and then subtracting the template
from the original data at the location of the QRS peaks. That is what
you seem to describe, and that is where the function you're refering
to originates from. However, in our opinion at that time it was not
satisfactory. There is considerable variance in the shape (spatial and
temporal) of the ECG artifact as it appears in the MEG channels, which
means that a resudue of the artifact remains. An alternative strategy
that we have subsequently used is described here
http://neuroimaging.ruhosting.nl/fieldtrip/doku.php?id=fieldtrip:documentation:examples:use_independent_component_analysis_ica_to_remove_ecg_artifacts

best regards,
Robert



On 12 Feb 2009, at 15:49, Stancak, Andrej wrote:

> Dear colleagues,
>
>  I would like to clean MEG data from ECG artifacts. There is a routine
> artefact_ECG.m enabling to detect the QRS complex in an ECG trace.
> The question
> is whether there is (in FieldTrip or SPM8b) a method similar to the
> one
> implemented in BESA which takes the template (basically an averaged
> QRS plus
> interval encompassing the P and the T wave) and subtract it from
> each MEG (or
> EEG) trace. Compared to ICA, this method works much faster although it
> definitely may alter certain topographical features of MEG.
>
> Best regards
> Andrej
>
> Andrej Stancak, PhD.
> Professor for normal physiology
> Senior lecturer in psychology
>
> School of Psychology
> Eleanor Rathbone Building
> Bedford Street South
> L69 7ZA
> Liverpool
> United Kingdom
>
> Phone: 0044 0151 7946951
> E-mail: a.stancak at liverpool.ac.uk (primary)
>         stancak at lf3.cuni.cz (secondary)
>
> Office hours: Mo 10-12, Wed 10-12
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users
> of the FieldTrip  toolbox, to share experiences and to discuss new
> ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html
>  and http://www.ru.nl/fcdonders/fieldtrip.
>

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.



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