BESA is capable of automatically recognizing the electrode coordinates and their labels for certain EEG caps. Channels that have been successfully identified by BESA have 10-10 names (E.g. Fp1, C1, P3) and are called Scalp Channels. Channels that have not been successfully identified by BESA have different names (E.g. EXG1, EA7, EB28) and are called Polygraphic Channels. In order to match up polygraphic channels with their locations, additional files containing EEG cap information must be imported into BESA. Dr. Thom has several of these files stored in the computer. If none of the channels are polygraphic, you do not need to manually set channel locations.
Click on “Load Channel Configuration…” under the file tab
This warning will pop up. Click “Yes”
All the files on the computer will pop up. Go to…
Windows (C:)→Users→Public→Public Documents→BESA→Research_7_0→Montages→Channels
In the channels folder, there are folders of four different companies and the type of EEG caps they use. If you don’t know the type of cap used in the experiment, try counting the number of channels and finding a file in the StandardElectrodes that has around the same number of channels.
In the example above, I was able to find a file (81 electrodes) within the StandardElectordes folder that allowed BESA to recognize and locate each of the electrodes.
Here is a before and after setting the channel locations. Notice how the polygraphic channels are all black, with little readable data.
Also, if you need to upload files into BESA in order to add additional information about channel configuration (*.ela), digitized head surface points (*.sfp, *.eps), labels (*.sfn), etc., watch the tutorial in day 1 of the BESA workshop: 22:02 - 23:00
