FT_ELECTRODEPLACEMENT
Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_electrodeplacement”.
FT_ELECTRODEPLACEMENT allows manual placement of electrodes on a MRI scan, CT scan or on a triangulated surface of the head. This function supports different methods. VOLUME - Navigate an orthographic display of a volume (e.g. CT or MRI scan), and assign an electrode label to the current crosshair location by clicking on a label in the eletrode list. You can undo the selection by clicking on the same label again. The electrode labels shown in the list can be prespecified using cfg.channel when calling ft_electrodeplacement. The zoom slider allows zooming in at the location of the crosshair. The intensity sliders allow thresholding the image's low and high values. The magnet feature transports the crosshair to the nearest peak intensity voxel, within a certain voxel radius of the selected location. The labels feature displays the labels of the selected electrodes within the orthoplot. The global feature allows toggling the view between all and near-crosshair markers. The scan feature allows toggling between scans when another scan is given as input. HEADSHAPE - Navigate a triangulated scalp (for EEG) or brain (for ECoG) surface, and assign an electrode location by clicking on the surface. The electrode is placed on the triangulation itself. 1020 - Starting from a triangulated scalp surface and the nasion, inion, left and right pre-auricular points, this automatically constructs and follows contours over the surface according to the 5% system. Electrodes are placed at certain relative distances along these countours. This is an extension of the 10-20 standard electrode placement system and includes the 20%, 10% and 5% locations. See "Oostenveld R, Praamstra P. The five percent electrode system for high-resolution EEG and ERP measurements. Clin Neurophysiol. 2001 Apr;112(4):713-9" for details. Use as [elec] = ft_electrodeplacement(cfg, ct) [elec] = ft_electrodeplacement(cfg, ct, mri, ..) where the input mri should be an anatomical CT or MRI volume, or [elec] = ft_electrodeplacement(cfg, headshape) where the input headshape should be a surface triangulation. The configuration can contain the following options cfg.method = string representing the method for placing the electrodes 'volume' interactively locate electrodes on three orthogonal slices of a volumetric MRI or CT scan 'headshape' interactively locate electrodes on a head surface '1020' automatically locate electrodes on a head surface according to the 10-20 system The following options apply to the mri method cfg.parameter = string, field in data (default = 'anatomy' if present in data) cfg.channel = Nx1 cell-array with selection of channels (default = {'1' '2' ...}) cfg.elec = struct containing previously placed electrodes (this overwrites cfg.channel) cfg.clim = color range of the data (default = [0 1], i.e. the full range) cfg.magtype = string representing the 'magnet' type used for placing the electrodes 'peakweighted' place electrodes at weighted peak intensity voxel (default) 'troughweighted' place electrodes at weighted trough intensity voxel 'peak' place electrodes at peak intensity voxel (default) 'trough' place electrodes at trough intensity voxel 'weighted' place electrodes at center-of-mass cfg.magradius = number representing the radius for the cfg.magtype based search (default = 3) The following options apply to the 1020 method cfg.fiducial.nas = 1x3 vector with coordinates cfg.fiducial.ini = 1x3 vector with coordinates cfg.fiducial.lpa = 1x3 vector with coordinates cfg.fiducial.rpa = 1x3 vector with coordinates cfg.feedback = string, can be 'yes' or 'no' for detailled feedback (default = 'yes') See also FT_ELECTRODEREALIGN, FT_VOLUMEREALIGN, FT_VOLUMESEGMENT, FT_PREPARE_MESH