Note: In this plot, click on any channel label to see its channel number. Either command pops up a window like that below. Else, during an EEGLAB session, you may refer to a plot showing the channel locations by selecting Plot → Channel location → By name. To visualize the 2-D locations of the channels, press Plot 2-D above the Read Locations button. Reopen Edit → Channel locations if you closed it. Note that in the main EEGLAB window, the channel location flag now shows yes. It is essential to press Ok in the channel editing window above to actually import the channel locations. Therefore, it is well worth the effort to add channel types to your data. Other EEGLAB functions may use channel types to restrict plotting and computation to a desired subset of channel types, allowing easier analysis of multi-modal datasets. The Set channel type button allows you to enter a channel type associated with the channel (for example, ‘EEG’, ‘MEG’, ‘EMG’, ‘ECG’, ‘Events’, etc.). In the window below, you may scroll through the channel field values 1-by-1 using the >. In the next pop-up window, simply press Ok. Press the button Read locs help in the main channel graphic interface window to view the supported formats. If you do not specify the file format, the pop_chanedit.m function will attempt to use the filename extension to assess its format. For the current data file, you may select the sample channel locations file eeglab_chan32.locs (located in the sample_data sub-directory of the EEGLAB distribution). In case it is not possible to look up channel locations based on their labels, or if you have a scanned electrode file available, press the Read Locations button. Close the channel editing window (using Cancel to discard the entered locations), then proceed to the next section. Press Plot 2-D to plot the channel locations. Then call Edit → Channel locations and look up channel locations. In the MATLAB command window, type:Ĭhanlocs = struct ( 'labels', ) pop_chanedit ( chanlocs ) Press Ok.Ĭommand-line channel location look up exampleīelow, we will build a channel structure using channel labels only, then will call the channel editing window. If you intend to perform source localization, we strongly suggest that you select the second option, “Use MNI coordinates for the BEM Dipfit model” (the first set of ‘BESA’ coordinates was designed for a spherical BESA head model, now obsolete). You may choose between several templates. A dialog box (shown below) will appear, asking you if you want to use standard channel locations based on the imported electrode position labels (for example, ‘Fz’) from a channel locations file using an extended International 10-20 System. To load or edit channel location information contained in a dataset, select Edit → Channel locations. Before 2021, it was the BESA spherical location file. As of 2021, the default channel location file for electrode position is the MNI file, which is best suited for source localization. You may add additional standard channel locations to this file if you wish. When you then call the channel editing window, the function will look up 10-10 channel locations in a database of 385 defined channel labels, the file “Standard-10-5-Cap385.sfp” in the “functions/supportfiles” sub-folder of the EEGLAB distribution. EEGLAB will automatically read these channel labels. For instance, when importing a Neuroscan, or a Biosemi channel locations file, channel names are often stored in the file header. Its intent is to provide guidelines for automatically finding channel locations when channel names are known. This section does not use the tutorial dataset. Select the tutorial file “eeglab_t” distributed with the toolbox, and located in the “sample_data” folder of EEGLAB. Select the File menu item and press the Load existing dataset sub-menu item. Adjusting scanned 3-D channel locations.Why are electrodes plotted outside of the head limits?.Command-line channel location look up example.To plot EEG scalp maps in either 2-D or 3-D format, or to estimate source locations of data components, an EEGLAB dataset must contain information about the scalp locations of the recording electrodes.
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