[FieldTrip] ft_channelrepair with channel absent from data
l.roijendijk at donders.ru.nl
Thu Dec 20 18:31:38 CET 2012
I have also been trying to reinterpolate MEG channels that were never recorded with the nearest neighbour interpolation method, however when calling the method (in the same way Tom also used it) the function seems to do something, however it did not interpolate the missing sensors.
There were still 273 sensors instead of 275. Do I need to give along a special cfg.grad or do something else?
Thanks in advance,
On Nov 26, 2012, at 10:45 AM, Jörn M. Horschig <jm.horschig at donders.ru.nl> wrote:q
> 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).
>> Thanks for help with any of the above!
>> 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
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
> 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
> 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
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
Linsey Roijendijk MSc.
Donders Institute for Brain, Cognition and Behaviour
Centre for Neuroscience
dept. of Biophysics
Radboud University Nijmegen
Montessorilaan 3, Room B.02.34
6500 HE Nijmegen
Tel: +31(0)24 3612616
L.Roijendijk at donders.ru.nl
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