[FieldTrip] Restricting dipoles to cortex

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

Hi Tim,

Not exactly sure what the optimal answer is here, but from your formulation I get the impression that you use ‘classical’ dipole fitting for the source reconstruction, i.e. assume a limited number of sources that account for the observed sensor data, and estimate their location and activity profile. The non-linear search for the optimal dipole positions is probably constrained to the innermost compartment of your volume conduction model (assuming that you are using a nested spheres model, or a nested BEM model). As far as I know there’s now way to further constrain the solution to a subcompartment of the brain compartment.

If, on the off chance, you are using a distributed source model (e.g. MNE) or beamformers then you can constrain the source model to the cortex or anything else that would be to your liking.

Best wishes,
Jan-Mathijs


On 29 Jun 2022, at 21:56, Tim Redepenning via fieldtrip <fieldtrip at science.ru.nl<mailto:fieldtrip at science.ru.nl>> wrote:

Dear community,

I am currently working with functional connectivity (EEG data) with eeglab and a plugin called SIFT. The source estimation is based on dipole fitting which relies on fieldtrip scripts.
Now, lots of the dipoles are placed too deeply into the brain what makes my results -at least- questionable. Is there a way to restrict the dipole fitting to the cortex surface? Or is this rather an issue of the following source estimation and less of the dipole positions?

Best wishes
Tim

Tim Redepenning

PhD Student | “Motor Control and Training” – Research Group
Faculty of Psychology and Sports Science
Bielefeld University | Cognitive Interaction Technology – Center of Excellence (CITEC)
33501 Bielefeld
Germany

Room: CITEC-1.411 | Phone: +49-(0)521-106-5129
E-Mail: tim.redepenning at uni-bielefeld.de<mailto:tim.redepenning at uni-bielefeld.de>

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