[FieldTrip] Fieldtrip dipole fit

[Schoffelen, J.M. (Jan Mathijs)]

Hi Rita,

I don’t know what a ‘cluster mixing matrix of the components’ is.
Generally, you’d need to create a fieldtrip-compatible data structure of  the type ’timelock’ (see ft_datatype_timelock, look for it on the website and in utilities/ft_datatype_timelock), or of the type ‘comp’ (see ft_datatype_comp).

If the above mentioned cluster mixing matrix of the components is the same as just the mixing matrix that transforms from components to channels, then this is what in FieldTrip is known as the ’topo’ matrix.

If you do a targeted search on the fieldtriptoolbox.org<http://fieldtriptoolbox.org> website (don’t forget to look into the FAQ, tutorial and example script sections) I am pretty sure that you can find the necessary information.

Also, it might be useful to study the code in ft_componentanalysis, which is a wrapper around a host of blind-source separation algorithms. Feel free to add functionality for the arabica method, and submit this as a PR on github.

Best wishes,

Jan-Mathijs


On 16 Jun 2019, at 23:37, Rita Martins <rt.martins at campus.fct.unl.pt<mailto:rt.martins at campus.fct.unl.pt>> wrote:


Hi Jan Mathijs,

Thank you for your help.

I'm using function api_ica_estimate (https://bazaar.launchpad.net/~arabica-core-dev/arabica-ica/1.0/view/head:/api_ica_estimate.m) in order to obtain the cluster mixing matrix of the components. How could I import this data to fieldtrip so I can do the dipole fitting?
I’m having some trouble understanding what is actually needed from a data point of view.

Thanks in advance.
Best regards,

Rita Martins

Schoffelen, J.M. (Jan Mathijs) <jan.schoffelen at donders.ru.nl<mailto:jan.schoffelen at donders.ru.nl>> escreveu no dia domingo, 16/06/2019 à(s) 20:12:
Hi Rita,

> I would like to perform a dipole fit with the data from an algorithm I'm using to process the signal, however, reading through the tutorials online, it seems I would need an original signal acquisition file (*.fif) to get the dipole position? Or is there any way to perform the dipole fitting with a subset of data and some neuromag templates?

I think yes, but am not entirely sure, because I don’t know exactly what you mean with

‘a subset of data’, and ’some neuromag templates’.

Could you be a bit more specific please?

In general, once you have a spatial topography of observed data, and a volume conductor model of the head in combination with a specification of the position of the MEG sensor coils, (expressed in the same coordinate system as said volume conduction model) you should be ready to go.

Best wishes,
Jan-Mathijs


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