[Eeglablist] Choosing right head model in Dipfit with BrainProducts Cap

[Makoto Miyakoshi]

Dear Maya,

It seems the dipoles were fitted only by 'coarse fit' and not with 'fine
fit'. That's why you see the apparent grid structure there. Make sure you
performed 'autofit' because it does both coarse and fine fit. If you are
sure you did 'autofit', then it failed for some reason. If that's the case,
check the error/warning message and tell me what it says.

Makoto

On Wed, Jul 27, 2016 at 3:50 PM, Maya Pinacle <mayapinacle at gmail.com> wrote:

> Hi all,
>
> I collected my data with 32 channel BrainProducts cap, and would like to
> locate dipoles via Dipfit. I tried to use manual Co-registration option
> choosing BEM MNI as head model however unfortunately it is not working well
> and it is very difficult to align the electrode template with my own
> electrode locations.
>
> However tutorial says that if the electrode locations within the
> Internaitional 10-20 system best way is to use standard channel coordinates
> associated with the head model. So as I know BrainProducts caps are in
> 10-20 systems so I used this option with recomended settings, choosing
> Boundary Element Mode (MNI) as Head model with No Coregistration to be
> chosen.
>
>
>  The tutorial also says to go to channel locations from edit option of
> EEGLAB and look up for the channel locations. In which case I choose ''use
> MNI coordinate file for BEM dipfit model'' option. In each condition
> (Coarse  fine or auto fit ) the coordinates of the dipoles seems sort of
> overlapping rather than spreaded all over the brain. And when I create
> STUDY from different subjects file and cluster the component dipoles they
> lined up in a very straight coordinates (I have added 4 pictures.)
>
> When I compare visually a component and a dipole that represents it, it
> seems that estimation of the dipole location is pretty good with those
> selection of options as it was described in the tutorial. However, this
> very well organised appearance of the dipoles in a cluster made me think
> that whether something wrong with it. Because it seems like rather than
> finding actual source, the dipoles try to locate around the channels and I
> wonder whether the result is kind of misleading. So I wonder is there
> anyone would like to comment on that? I can also share the data in the case
> you would like to see.
>
> So from one data the clusters and dipole locations can be found here.
>
> Cluster 1 - 33 dipoles - Sagital
> https://www.dropbox.com/s/rf77qcznrk7bvia/cluster1_sagital.png?dl=0
>
> Cluster 1 - 33 dipole - Top
>
> https://www.dropbox.com/s/9l2p7l7kmlsz7r0/cluster1_top.png?dl=0
>
> Cluster 2 - 62 dipole Sagital
>
> https://www.dropbox.com/s/cphtiemq05xeacu/cluster2_sagital.png?dl=0
>
>
> Thank you
>
> Maya
>
> Cluser 2 - 62 dipole Top
> https://www.dropbox.com/s/64ofdpixqo6bw4k/cluster2_top.png?dl=0
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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