[Eeglablist] Importing .bdf channel locations

[Andreas Widmann]

> Thanks very much, renaming the fields of EEG.chanlocs seems to have worked well with one exception: I don't know what to rename the two mastoids,
M1, M2

> the two HEOG channels,
LO1, LO2

> and the four VEOG channels
SO1, IO1, SO2, IO2

Odd numbers in left hemisphere.
Best, Andreas

> or, without renaming them, I don't know what coordinates to assign them.  I want to run an ICA so that I can remove eyeblink components but without being able to properly place the EOGs I'm not sure how I'd find the proper components.  Can you (or anyone else) suggest the proper way to localize the remaining electrodes?
> 
> Best,
> Brett
> 
> On Sat, Jan 23, 2016 at 7:30 PM, Stephen Politzer-Ahles <stephen.politzer-ahles at ling-phil.ox.ac.uk> wrote:
> Looking up the channel names from the BESA template requires that you have standard 10-20 names (e.g. F7, Cz, etc.). These names are probably set somewhere in your Biosemi acquisition setup. For files that you've already recorded that have a different naming scheme, you could manually change the channel names after loading the data in EEGLAB (using a loop to go through each element of EEG.chanlocs and change the name) and then the template should work.
> 
> Best,
> Steve
> 
> 
> 
> ---
> Stephen Politzer-Ahles
> University of Oxford
> Language and Brain Lab
> Faculty of Linguistics, Phonetics & Philology
> http://users.ox.ac.uk/~cpgl0080/
> 
> On Sun, Jan 24, 2016 at 1:24 AM, Brett Christopher Bays <brett.bays at email.ucr.edu> wrote:
> Hi all,
> 
> Relative newbie to EEGLAB here, so I apologize if I'm missing something obvious, but I cannot figure out how to properly assign channel locations to my bdf data in EEGLAB.  I'm using a BioSemi ActiveTwo 64+8 channel setup (2 mastoids, 2 horizontal eog, 2 vertical lower eog, 2 vertical upper eog) and have an .elp file created in EMSE with all of the matched locations for each electrode.  The .bdf file loads into EEGLAB fine, but trying to load the .elp file using the "Read locations" option of Edit->Channel locations produces the following:
> 
> TIP: Call this function directy from the prompt, ">> pop_chanedit([]);"
>      to convert between channel location file formats
> readlocs(): 'polhemus' format assumed from file extension
> readlocs(): Could not read Polhemus coords. Trying to read BESA .elp file.
> readlocs(): 'besa' format assumed from file extension
> readlocs() warning: Fewer columns in the input than expected.
>                     See >> help readlocs
> BESA format detected ( Theta | Phi )
> 
> [then multiple copies of this warning:]
> 
> Warning: Out of range or non-integer values truncated during conversion to character. 
> > In convertlocs (line 180)
>   In convertlocs (line 200)
>   In readlocs (line 485)
>   In readlocs (line 396)
>   In pop_chanedit (line 664)
>   In inputgui (line 204)
>   In pop_chanedit (line 350) 
> 
> [then:]
> 
> Warning: coordinate conversion failed
> Readlocs: BESA spherical coords. converted, now deleting BESA fields
>           to avoid confusion (these fields can be exported, though)
> readlocs(): Inserting electrode labels automatically.
> Warning: coordinate conversion failed
> >> 
> 
> If I allow EEGLAB to look up coordinates using its default of "BESA file for 4-shell dipfit spherical model", I get the following error:
> 
> readlocs(): 'BESA' format assumed from file extension
> BESA header detected, skipping three lines...
> Readlocs: BESA spherical coords. converted, now deleting BESA fields
>           to avoid confusion (these fields can be exported, though)
> Channel lookup: no location for A3,A4,A5,A6,A7,A8,A9,A10,A11,A12,A13,A14,A15,A16,A17,A18,A19,A20,A21,A22,A23,A24,A25,A26,A27,A28,A29,A30,A31,A32,B1,B2,B3,B4,B5,B6,B7,B8,B9,B10,B11,B12,B13,B14,B15,B16,B17,B18,B19,B20,B21,B22,B23,B24,B25,B26,B27,B28,B29,B30,B31,B32,EXG1,EXG2,EXG3,EXG4,EXG5,EXG6,EXG7,EXG8,Status
> Send us standard location for your channels at eeglab at sccn.ucsd.edu
> >> 
> 
> Can anyone offer any suggestions or tell me if I'm doing something obviously wrong?  I've read through the EEGLAB Tutorial and tried searching through the archives of this mailing list and found what might be similar problems but couldn't find a solution.  Any help is appreciated, thanks!
> 
> Best,
> Brett
> 
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