[FieldTrip] ft_sourceplot: issue with cfg.method = 'surface'

[jan-mathijs schoffelen]

Dear fieldtrippers,

Despite our best efforts, there has been an inconvenient bug in ft_sourceplot, which has been present in r9031-r9400 (Dec 13, 2013-April 12,2014). In particular, the images constructed when using cfg.method = 'surface' were incorrect. The issue pertains to the on-the-fly interpolation onto a cortical sheet of volumetrically (i.e. on a 3D grid) source-reconstructed data.
I updated the cortical sheets last December, and replaced the handcrafted exemplars by the ones from the SPM surfrend toolbox. The motivation for all this would be to have a better reference to the actual data used. The bottom line of all this is that I made a mistake, and directly used the surfaces loaded from the Freesurfer file format, without taking into account the fact that in the Freesurfer convention the coordinate system in these files is slightly different than standard space. As a consequence these surfaces were misregistered to the 3D anatomical image in standard space, and thus to incorrect interpolations of the functional data onto these surfaces. 
This issue has been identified thanks to Marlene Bönstrup and has been fixed today. Any sourceplots with cfg.method = 'surface' that have been made with FieldTrip versions originating from between the dates mentioned above will incorrectly represent the source reconstructed data, and may need to be re-done. More info can be found on http://fieldtrip.fcdonders.nl/template/anatomy.
I am very sorry for any inconvenience this may have caused.

Best wishes,

 Jan-Mathijs Schoffelen, MD PhD 

Donders Institute for Brain, Cognition and Behaviour, 
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands

Max Planck Institute for Psycholinguistics,
Nijmegen, The Netherlands

J.Schoffelen at donders.ru.nl
Telephone: +31-24-3614793

http://www.hettaligebrein.nl

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