[FieldTrip] Neighbors for Elekta Neuromag 306 gradiometers separately?

Lin Wang wanglinsisi at gmail.com
Wed Oct 5 17:21:19 CEST 2016

Dear all,

I have the same question. Do we need to separate the two gradiometer
sensors at one position when defining the neighbours for interpolating bad



On Thu, Sep 17, 2015 at 3:43 AM, Darinka Trübutschek <darinkat87 at gmail.com>

> Dear Fieldtrip community,
> I am new to MEG/fieldtrip and have a question regarding the neighbor
> structure necessary for computing cluster-based statistics. I am currently
> analyzing data from a Neuromag 306 system (with 102 Mags and 204 Grads) and
> would like to look separately at Mags, Grad1, and Grad2.
> I assume that this means that I also need to compute the neighbors
> separately for the different channel types.
> My question therefore concerns fieldtrip's standard neighbor templates for
> Neuromag. Is there a specific reason (theoretical or methodological), why
> there are no separate templates for Grad1 and 2? All that I could find are
> separate templates for Mag (neuromag306mag_neighb.mat), the combined planar
> gradients (neuromag306cmb_neighb.mat), and the neuromag306planar_neighb.mat
> template, which, if I understand correctly, does not combine the Grads, but
> still lists sensors of one type as neighbors of sensors of another type
> (e.g., for sensor 0713 - a gradiometer measuring the derivative along the
> longitudinal component, the neighbors listed include 0432, 0723, but also
> sensors that, if I interpret it correctly, should measure the derivative
> along the latitudinal component, such as 0433, 0712, etc.) Is there a
> specific reason, why sometimes, for a given sensor position, both Grad1 and
> Grad2 are included in the neighbors (e.g., 0432 and 0433), but sometimes
> only one of the two (e.g., 0742)?
> Many thanks in advance for your help!
> Best,
> Darinka
> --
> Darinka Trübutschek (PhD Candidate)
> Inserm-CEA Cognitive Neuroimaging Unit
> CEA/SAC/DSV/DRM/Neurospin
> Bât 145, Point Courier 156
> F-91191 Gif-sur-Yvette
> website: https://sites.google.com/site/dtruebutschek/
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