Channel File Import Error

Discussions
1

Hello everyone,

I am having trouble importing the EEG channel file from the BIOSEMI 128 system into Brainstorm. I had a spreadsheet of all electrode names and their coordinates, which I then transformed into a matlab structure through the following code:

% Get spreadsheet from Python
filename = "\BIOSEMI128.xlsx";
data = readtable(filename);

Channel = struct;

% channel array from table
for i = 1:128
    Channel(i).Name = data{i, 1}{1};
    Channel(i).Loc = data{i, 2:4}';
    Channel(i).Type = 'EEG';
    Channel(i).Weight = 1;
    Channel(i).Orient = [];
end

% Headpoints structure
HeadPoints = struct;
HeadPoints.Loc = [];
HeadPoints.Label = [];
HeadPoints.Type = [];

% Finalize structure
chanFile.Channel = Channel;
chanFile.Comment = "BIOSEMI 128";
chanFile.HeadPoints = HeadPoints;

save("\channel_BIOSEMI128.mat", '-struct', 'chanFile');

To summarize, I just created the fields Channel (1x128 struct with fields Name, Loc, Type, Weight), Comment, and HeadPoints (empty 1x1 struct), forming them into a single structure saved into a .mat file. I based this off the structure of another .mat channel file of a different system that worked, but when I tried importing this one into Brainstorm, I got the following error:

Error: Line 667: No method 'add' with matching signature found for class 'org.brainstorm.tree.BstNode'.
** 
** Call stack:
** >node_create_study.m>node_create_study/CreateNode at 667
** >node_create_study.m at 69
** >panel_protocols.m>CreateStudyNode at 577
** >panel_protocols.m at 46
** >tree_callbacks.m at 113
** >bst_call.m at 26
** >panel_protocols.m>CreatePanel/protocolTreeClicked_Callback at 156
** >bst_call.m at 28
** >panel_protocols.m>@(h,ev)bst_call(@protocolTreeClicked_Callback,h,ev) at 75

Could someone please help me out with this? Thank you!

2

Hi @jonathanhy314
How are you doing to import this channel file?

3

Hello,

I am still having trouble getting the channel file to properly be imported into Brainstorm. I will attach two .mat channel files below: one is the channel file for the GSN EEG system (which works), and the other is the channel file that I tried to create myself for the BIOSEMI EEG system.
channel_GSN_HydroCel_128_E1.mat (5.9 KB)
channel_BIOSEMI128.mat (5.8 KB)

Both are Matlab structures, and I tried to build the BIOSEMI channel file based off the GSN channel file, with the same fields Channel, Comment, HeadPoints, History, MegRefCoef, Projector, SCS, TransfEeg, TransfEegLabels, TransfMeg, and TransfMegLabels. Most of the fields are empty, but I adjusted the structure array for the "Channel" field with the names, weights, xyz locations, etc.

However, when I try to import the BIOSEMI channel file into Brainstorm, it says, "Warning: No channel information was read from the file."

This information is in the .mat files I attached, but I suspect that the main issue is in the "Channel" structure array, so here is a screenshot of the fields in the first element:

image
image464×195 2.74 KB

Help would be greatly appreciated.

4

@jonathanhy314 for the channel_BIOSEMI128.mat file and from the image you shared I see that you have the locations (Loc) comma separated which creates row vectors.

In Brainstorm, the locations are expected to be in column vectors. In your case make the locations semi-colon separated and retry importing the .mat file.

For more details refer to this thread: channel.Loc semicolon

5

Thank you, this is very helpful!