[FieldTrip] ft_channelrepair with channel absent from data

["Jörn M. Horschig"]

Hey Tom,

>
> I guess I have several questions all at once:
> 1) Is it actually possible to reinterpolate MEG channels that were 
> never recorded - eg because the channels were deactivated when the 
> acquisition took place?

Should work, but only with the SSI (=spherical spline interpolation) 
method. For the nearest neighbour interpolation, the function constructs 
a list of neuighbouring and constructs a weighted average. The function, 
however, wants to weigh each sensor according to its distance from the 
sensor to be reconstructed. That information can only be found in the 
grad structure, but in the grad structure there are only sensors which 
were recorded, thus the distance from a missing sensor cannot be 
measured because its position is missing in the grad structure. SSI 
should work though, cause it relies on a different rationale.


> 2) What might be causing the error I'm seeing?

Since you have 301 channels rather than 275, my suspicion is that you 
include reference gradiometers. This should not fail in principle, 
though... maybe I can drop by your office to check it out? Got some time 
right now?

> 3) Where is ft_fetch_sens?

It's a private function, can be found in FieldTrip/private. You have to 
cd to that directory in order for Matlab to find it (the idea behind 
private function is that there are only visible for higher-level 
function and 'hidden' for all other functions).

Best,
Jörn


>
> Thanks for help with any of the above!
> Best,
> Tom
> -- 
> Tom Marshall, MSc.
> Neuronal Oscillations Group, Donders Centre for Cognitive Neuroimaging
> tel: +31(0)243668487
> email:t.marshall at fcdonders.ru.nl
> postal: PO Box 9101, 6500HB, Nijmegen, The Netherlands
> visiting: Kapittelweg 29, 6525EN, Nijmegen, The Netherlands
>
>
> _______________________________________________
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> fieldtrip at donders.ru.nl
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-- 
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team

P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

Contact:
E-Mail: jm.horschig at donders.ru.nl
Tel:    +31-(0)24-36-68493
Web: http://www.ru.nl/donders

Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands

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