[Eeglablist] practical questions about Dipfit

[Mircea Stoica]

Dear Carolina,

if you're fitting dipoles to independent components, data epochs are not
used in the dipole fitting process itself. Only the IC scalp maps and the
forward model are needed.
Therefore, the quality of your dipole localization depends on the quality
of your ICA, which benefits greatly from having:
1 - clean data (devoid of non-stereotypical artifacts, don't worry about
EMG and EOG)
2- as much data as possible

With respect to question 3, local minima are conceptually always possible
for the simple reason that you don't scan the entire brain volume at
infinite resolution, so there's no way of knowing if a lower objective
value might be possible at some unexplored location.
In practice you shouldn't worry about this though.


Best,
Mircea

On Thu, Nov 9, 2017 at 4:44 PM, Carolina Pletti <carolina.pletti at gmail.com>
wrote:

> Dear EEGlab community,
>
> I have a few questions regarding Dipfit.
>
> 1 - would you recommend fitting the dipoles before or after artifact
> rejection?
> 2 - Is there any suggestions on whether to run it on long (e.g. 3000 ms or
> more) vs short (e.g. 1000 ms) data epochs?
> 3 - what should one do when it finds a local minimum, or when a local
> minimum is possible? Is it normal that it is *always *possible?
>
> Thank you very much!
>
> Carolina Pletti
>
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