[FieldTrip] Problem using ft_sensrorealign with Yokogawa MEG

Victor RG victor.rg.gib at gmail.com
Tue Oct 30 10:43:08 CET 2018

HI Fieldtrip experts!

I'm trying to align a headmodel (the one from example "Subject1") with my
MEG sensors (Yokogawa system).

I'm trying to do that interactively, in order to construct a Leadfied
matrix as accurate as possible. To do that, I am testing this code:

*cfg = [];*
*cfg.method = 'interactive';*
*cfg.headshape = vol.bnd(1);*
*cfg.senstype = 'meggrad';*
*grad_aligned = ft_sensorrealign(cfg, grad); % Im using ft_sensorrealign
cause I think is the MEG version of ft_electroderealign*

The variables employed consist of:
*>> grad = *
struct with fields:

   - balance: [1×1 struct]
   - chanori: [160×3 double]
   - chanpos: [160×3 double]
   - chantype: {160×1 cell}
   - chanunit: {160×1 cell}
   - coilori: [320×3 double]
   - coilpos: [320×3 double]
   - label: {160×1 cell}
   - tra: [160×320 double]
   - type: 'yokogawa160'
   - unit: 'cm'
   - fid: [1×1 struct]

*>> vol.bnd(1) =*
struct with fields:

   - pos: [1000×3 double]
   - tri: [1996×3 double]
   - coordsys: 'ctf'

I have looked at the tutorial for EEG sensors realignment, and I have
copied the procedure, since there is not a specific tutorial for MEG
sensors. I thought it would be the same, but when executing it I obtain the
following errors:

*>> Undefined function 'fixpos' for input arguments of type 'struct'.*

*Error in ft_sensorrealign (line 255)*
*headshape = fixpos(cfg.headshape);*

*Error in generating_leadfield (line 63)*
*grad_aligned = ft_sensorrealign(cfg, grad);*

Does anybody know how to do that, or how to do an interactive realignment
with MEG sensors?

Thanks in advance.

Víctor Rodríguez González
Grupo de Ingeniería Biomédica, ETSIT.
Universidad de Valladolid, España.
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