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

[Maya Pinacle]

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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