[Eeglablist] Dipole Fitting - Dipoles' moment

Robert Thatcher rwthatcher2 at yahoo.com
Tue Jun 13 14:51:37 PDT 2017


Niels,

   I am new to theEEGLab list and am not sure exactly how you are fitting dipoles or how many,etc.  When I worked at NIH in the 1990swe dealt with these issues including dipole coherence and dipole phasedifferences, here is a url to one of our publications that may be helpful: 

http://www.appliedneuroscience.com/HumanNetworkDynamics.pdf

 

Recently we recognize that the 3D vectors have differentorientations depending on their location in gyri and sulci and therefore relianceon the resultant vector (square root of the sum of squares) for connectivity analyses is not always thebest.  Instead we identify the x or y orz vector that has the largest magnitude or largest contribution to the inverse solution and then compute coherenceand phase lags and cross-frequency coupling and effective connectivity, etc. betweenthe strongest  vector or dipole moment no matter whetherit is x or y or z.  Have you tried thisapproach or am I off base about what you are trying to do?

 

Best regards,

 

Robert


On Tuesday, June 13, 2017, 5:34:56 PM EDT, Tarik S Bel-Bahar <tarikbelbahar at gmail.com> wrote:

Hello Nils, quick note below, best wishes.

I believe the eeglab approach is to use dipfit for finding dipoles
that accurately explain spatial IC maps, thus there is no temporal
information that the dipoles are explaining, in this case, in eeglab.

You probably need to get some way to get dipole fits over time, which
may require transitioning from eeglab to fieldtrip or brainstorm,
where surely that functionality exists.






On Mon, Jun 12, 2017 at 3:55 AM, Nils Hachmeister
<nils.hachmeister at uni-bielefeld.de> wrote:
> Hall again,
>
> my topic is still dipole fitting, but as this question is otherwise
> unrelated to my first question I gave it a separate post.
>
> When performing dipole fitting with EEGLAB-dipfit I only ever came across
> single 3-d vectors as representations for a dipole's moment. It is my
> understanding of dipole fitting that the dipole's moment should change over
> time, thereby generating the activity explaining the IC-activation (minus
> the RV).
>
> I understand that having one, adequately chosen moment (representation) per
> dipole during dipole fitting is handy. However, I intended to perform a
> connectivity analysis on the dipole-activation (more precisely on the
> moments' norm). Is there some way to obtain such information from the dipole
> model? Or is this the wrong approach?
>
> Best Regards
>
> Nils
>
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