[FieldTrip] simultaneous artifact and ICA viewing in ft_databrowser

Stan van Pelt s.vanpelt at fcdonders.ru.nl
Mon Oct 6 09:16:45 CEST 2014

Dear fellow FieldTrippers,


For proper artifact removal, I would like to compare the (temporal)
correspondence between the ICA components of my (CTF MEG275) data and the
artifacts that I semi-automatically identified beforehand (eye blinks,
saccades, muscle tension). ft_databrowser in principle allows me to show
this, but I run into some problems that I think have to do with data
resampling. The code I use is:


% iii. plot the components for visual inspection and select bad components

cfg              = [];

cfg.component    = [1:10]; % components to be plotted

cfg.layout       = 'CTF275.lay'; % specify the layout file that should be
used for plotting


% add preveiously manually defined eog and muscle artifacts, to compare
with components 

load artifact_eog_all

load artifact_muscle_all    




% visual inspection

ft_databrowser(cfg, comp150);


The problem I have is that the artifacts are not shown at the right
moments in time during the experiment. The data that are ICA-ed are
resampled from 1200->150Hz, but I do not know how I can 'resample' the
artifact definitions, since they are defined in samples, not in time. If I
manually resample (by dividing the values by a factor 8), they are still
not displayed at the correct moments in time.

I have the impression that convert_event (fieltrip/private) could be of
use here, but I cannot figure it out correctly.






Stan van Pelt, PhD

Donders Institute for Brain, Cognition and Behaviour

Radboud University

Montessorilaan 3, B.01.34

6525 HR Nijmegen, the Netherlands

tel: +31 24 3616288 


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