[Eeglablist] practical questions about Dipfit

Tarik S Bel-Bahar tarikbelbahar at gmail.com
Thu Nov 9 10:19:01 PST 2017


Hello Carolina,

1. ICA and dipoles should only be computed after artifact rejection. If you
haven't had a chance yet, do the eeglab tutorial with the eeglab tutorial
data to learn about the necessary steps before, during, and after dipfit.
You can also google many past eeglablist questions about similar topics
(just google eeglablist + topic). There are many steps before dipfit, and
they should all be done well. See also past eeglablist posts about ideal
data processing pipeline, as well as the suggestions in Makoto's pipeline
page.

2. Epoch length depends on your paradigm/protocol, you should emulate
published articles using similar protocols as you have. You can also test
for yourself the quality of dipfit solutions by examining what happens with
1000 ms vs. 3000 ms. epochs. Overall I don't believe it would make a big
difference for dipfit.

3. Not sure. I would say it depends on how good/clean/valid your ICs are.
You may also want to read up more about the whole process/theory behind
fitting dipoles to scalp maps, and source estimation in general. You can
review extensive tutorials from eeglab, eeglab school videos, past eeglab
posts, and the excellent videos from the Fieldtrip creator on youtube about
dipfit and source estimation.



On Thu, Nov 9, 2017 at 7:44 AM, 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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