[Eeglablist] Channel Locations for BioSemi- Off centre problem

[Makoto Miyakoshi]

Which channel is off the location? To me it looks fine.

For your information, the contour of the head plot is defined by the
following (Oostenveld and Praamstra, 2001, p.714).

(citation starts)
A horizontal circumferential contour is determined over
the left temporal lobe from Fpz to Oz, through the location
which was marked at 10% above LPA. Along this contour,
the positions *Fp1, AF7, F7, FT7, T7, TP7, P7, PO7 and O1*
*are marked at 10% distances* (Fig. 1, innermost circle). The
circumferential contour over the right temporal lobe is
determined in the same fashion from Fpz to Oz over the
location 10% above RPA, and the positions *Fp2, AF8, F8,*
*FT8, T8, TP8, P8, PO8 and O2* are marked at 10% distances.
(citation ends)

Makoto


On Fri, Aug 22, 2014 at 12:53 AM, Liat Levita <l.levita at sheffield.ac.uk>
wrote:

> Thank you so much Makoto.
>
> However see image attached, some locations are off the model head.
>
> Any thoughts? Rather worried about this.
>
> WIth best wishes,
>
> Liat
>
>
> On 22 Aug 2014, at 04:42, Makoto Miyakoshi <mmiyakoshi at ucsd.edu> wrote:
>
> Dear Liat,
>
> I often noticed it too, but every time I saw it I suspected this should be
> an optical illusion due to the labels plotted off the center... sorry if
> I'm not getting what you mean.
>
> Makoto
>
>
> On Thu, Aug 21, 2014 at 2:29 AM, Liat <l.levita at sheffield.ac.uk> wrote:
>
>> Hello dear all,
>>
>> I have seen a few posts about issues importing Biosemi Channel
>> coordinates to EEGLab. Following another post, I have made some progress in
>> doing this (created a .txt file to upload locations, which I hope is
>> correct)
>>
>> Method used:
>>
>> *1.* Typed following command
>>
>> * pop_chanedit(readlocs('biosemi_eloc.txt', 'format', { 'labels'
>> 'sph_theta_besa' 'sph_phi_besa' }, 'skiplines', 1))*
>>
>> *'biosemi_eloc.txt’ – File containing biosemi coordinates
>> and electrode locations names - at end of message pasted in what is in
>> that text file.*
>>
>> *2.* A pop_chanedit() GUI will come up – press *Okay*
>>
>> *3. * A pop_chanedit() GUI will come up – which now contain the Biosemi
>> coordinate space (as specified in the text file). Now you can save this
>> information as a  .ced file (also attached), which I can be used to edit
>> the location channels more easily in the future.
>> However,  but when I plot (2D) I can see some channel locations off the
>> model head, most look okay, but some seem to be to be positioned to much to
>> left (out of the head), even though CZ does seem to be in the middle. How
>> does one fix this? and is this a real problem? The 3D looks okay.
>>
>> Thank you for your help in advance,
>>
>> Liat
>>
>> PS.
>>
>> *biosemi_eloc.txt’*
>> Electrode _ _
>> Fp1 -92 -72
>> AF7 -92 -54
>> AF3 -74 -65
>> F1 -50 -68
>> F3 -60 -51
>> F5 -75 -41
>> F7 -92 -36
>> FT7 -92 -18
>> FC5 -72 -21
>> FC3 -50 -28
>> FC1 -32 -45
>> C1 -23 0
>> C3 -46 0
>> C5 -69 0
>> T7 -92 0
>> TP7 -92 18
>> CP5 -72 21
>> CP3 -50 28
>> CP1 -32 45
>> P1 -50 68
>> P3 -60 51
>> P5 -75 41
>> P7 -92 36
>> P9 -115 36
>> PO7 -92 54
>> PO3 -74 65
>> O1 -92 72
>> Iz (inion) 115 -90
>> Oz 92 -90
>> POz 69 -90
>> Pz 46 -90
>> CPz 23 -90
>> Fpz 92 90
>> Fp2 92 72
>> AF8 92 54
>> AF4 74 65
>> Afz 69 90
>> Fz 46 90
>> F2 50 68
>> F4 60 51
>> F6 75 41
>> F8 92 36
>> FT8 92 18
>> FC6 72 21
>> FC4 50 28
>> FC2 32 45
>> FCz 23 90
>> Cz 0 0
>> C2 23 0
>> C4 46 0
>> C6 69 0
>> T8 92 0
>> TP8 92 -18
>> CP6 72 -21
>> CP4 50 -28
>> CP2 32 -45
>> P2 50 -68
>> P4 60 -51
>> P6 75 -41
>> P8 92 -36
>> P10 115 36
>> PO8 92 -54
>> PO4 74 -65
>> O2 92 -72
>>
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>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
>
>


-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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