[Eeglablist] DIPFIT result interpretation ?

[Tarik S Bel-Bahar]

Hello Naveen, A few notes and recommendations for next steps below, good
luck with the process! Cheers.



Residual variance is term used often in "dipole fitting" and can generally
be thought of as representing
how well the dipole fits the ICA scalp map. Low RV is good, bad RV is high.
A good cutoff is 15%.

See mentions of residual variance here:
http://sccn.ucsd.edu/wiki/A08:_DIPFIT

See Delorme et al 2012 too to learn more about ICA and dipoles:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030135

Read the Onton & Makeig chapter from 2011, a preprint is here:
http://sccn.ucsd.edu/~scott/pdf/Makeig_Onton_LuckERP11.pdf
This chapter is good for learning about good and bad ICs.

You can use the eeglab STUDY function to use the dipfit results for
examining data
across multiple subjects. Remember that in eeglab, the IC activations
themselves are considered to represent the estimated activity of the
dipoles.
In other words, the dipole results themselves do not represent neural
"activity" over time, the ICs do.

Please review the items below if you have not had a chance to yet.
http://sccn.ucsd.edu/wiki/Chapter_02:_STUDY_Creation
http://sccn.ucsd.edu/wiki/Chapter_03:_Working_with_STUDY_designs


Ask google about "residual variance" and also about "dipole fitting EEG" to
learn more.
See the "source imaging or source analysis" documentation from besa, brain
products, fieltrip as well.

also, please be sure to  practice working with ICs and dipoles with the
eeglab tutorial
data first, so as to make sure that you understand how everything works
with proper dataset.

also, please be sure to download and test out  eeglab plugins such as
SASICA and
MARA to pick good ICs using multiple empirical criteria. Use google
to find these plugins. You may also use the eeglab add-plugin function
right from the eeglab gui.












On Mon, Sep 7, 2015 at 8:11 AM, Naveen Bhardwaj <naveenno122k at gmail.com>
wrote:

> Dear all EEGLAB members,
>
> I gone through DIPFIT tool ( which is good to plot source localization)
> but after plotting dipole  of the components i found difficulty in
> interpretation of components.
> So i have some questions,
>
> Q: What is residual variance and how do i interpret independent components
> based on  RV % ?  What RV% indicates ?
> Q: What different colors of the dipole indicates in the same independent
> components and their directions?
> Q: Is that possible to explain physiological significance of multiple
> subjects at one go using DIPFIT. cumulative study through DIPFIT
>
>
> Thanks for your help
>
> --
> *With Warm Regards *
>
>
> *Naveen Bhardwaj*
> *Research Scholar*
> PhD (Instrument Technology - Human Machine Interaction)
> Instrument Design & Development Centre
> Indian Institute of Technology, Delhi
>
> Skype Id- naveenb13
> Mobile: +91-9717173826
>
>
>
>
>
>
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