[FieldTrip] source localising activity coherent with muscle channels not present in leadfield
Schoffelen, J.M. (Jan Mathijs)
jan.schoffelen at donders.ru.nl
Thu Sep 12 17:35:20 CEST 2019
The EMG channels are not supposed to be added to the forward model.
The error that is thrown suggests indeed a mismatch between the channels in the data and/or their order, that are used for the covariance/csd matrix and the channels and/or their order in the precomputed forward model. I would start by inspecting the list of channels at the line in which the error occurs (either putting in an explicit breakpoint, or use the command 'dbstop if error’) in cfg.channel, and sourcemodel.label. I’d expect the cfg.channel to only contain the EEG channels, unless you put in a weird cfg.channel into the ft_sourceanalysis’ cfg. Note that you don’t need to put in a cfg.channel at this stage.
On 12 Sep 2019, at 16:27, Kirstin Heise <kirstin.heise at kuleuven.be<mailto:kirstin.heise at kuleuven.be>> wrote:
Dear FieldTrip community,
I am following the pipeline of the http://www.fieldtriptoolbox.org/tutorial/beamformingextended/#loading-of-the-data tutorial to source localise EEG activity that is coherent with muscle/EMG channels. I have a pre-computed leadfield (using simbio), which does not include the muscle channels that I want to use.
When attempting to run ft_sourceanalysis, I receive the following error message:
Error using ft_sourceanalysis (line 542)
There's a mismatch between the number/order of channels in the data,
with respect to the channels in the precomputed leadfield/filter.
This is not easy to solve automatically. Please look into this.
Is there a way of solving this post hoc? I am not sure which information is required in which part of the leadfield structure. I saw that in the tutorial data set, there are more sensors in the data set than included in the forward model and wonder whether it is just a matter of adding the additional channels “somehow” in the forward model?
Also, not having interpolated bad channels and hence having a different number of channels in the EEG data set, at what point can I control the numbering/order of the actual channels in the source reconstruction procedure?
Thanks a lot for your support.
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