[Eeglablist] Importing .bdf channel locations

Mon Jan 25 22:29:04 PST 2016

Thanks Steve, it's good to know that I might be able to get the eyeblink
components without the EOG channels.  I'm also not too concerned about
locating the mastoids.  However, it'd be a shame to waste the EOGs,
especially since they should be able to provide more information to the
ICA.  If there's anyone else who knows how I could assign the proper
locations for two HEOGs and four VEOGs I'd be very grateful.  Thank you!

Best,
Brett

On Mon, Jan 25, 2016 at 1:45 AM, Stephen Politzer-Ahles <
stephen.politzer-ahles at ling-phil.ox.ac.uk> wrote:

> Hi Brett,
>
> I haven't imported locations for these channels; maybe someone else on the
> list can give you more details.
>
> In my experience, I can usually get a good ICA separation (especially for
> blinks and saccades) without the EOG channels, so I often don't even
> include them. As for mastoids, I usually use them as my offline reference,
> so I don't bother importing their locations either. That is to say, for a
> simple ERP analysis without e.g. source localization and stuff like that,
> you might not need the locations for any of these channels.
>
> Best,
> Steve
>
>
>
> ---
> Stephen Politzer-Ahles
> University of Oxford
> Language and Brain Lab
> Faculty of Linguistics, Phonetics & Philology
> http://users.ox.ac.uk/~cpgl0080/
>
> On Mon, Jan 25, 2016 at 4:48 AM, Brett Christopher Bays <
> brett.bays at email.ucr.edu> wrote:
>
>> Hi Steve,
>>
>> 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, the two HEOG channels, and the four VEOG channels 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
>>>> formatsreadlocs(): 'polhemus' format assumed from file extensionreadlocs():
>>>> Could not read Polhemus coords. Trying to read BESA .elp file.readlocs():
>>>> 'besa' format assumed from file extensionreadlocs() warning: Fewer columns
>>>> in the input than expected.                    See >> help readlocsBESA
>>>> 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 failedReadlocs: 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 extensionBESA 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,StatusSend
>>>> us standard location for your channels at eeglab at sccn.ucsd.edu
>>>> <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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>>>
>>>
>>
>
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