[Eeglablist] Spread blinks and eye artifacts over IC

[mahsa shalchy]

Dear Tarik,

Thank you so much for your explanation. I had tried 1Hz HP cut-off and it
did not improve my ICA results and since I am also interested in early
components such as P1, I decided to go with 0.1 Hz. Also, I am visually
rejecting my epochs before feeding them to ICA but unfortunately I forgot
to mention. Using Luca's IC labeling and SASICA I'm able to keep only
neural components, however, mixed or "other" components are usually the
highest ICs ( IC3 to IC9) and by discarding them I am not only losing great
amount of information but also ending up with low SNR.

Many thanks,
Mahsa

On Mon, Nov 13, 2017 at 11:44 AM, Tarik S Bel-Bahar <tarikbelbahar at gmail.com
> wrote:

> Hello Mahsa,
>
> You may want to use a 1 Hz bottom for your filter to get better ICA.
>
> It's probably best to remove any components that are dominated by eye
> blinks.
>
> I would recommend just sticking with analysis of just the IC components
> that are valid/neural, and ignoring/discounting the rest.
>
> If you are rejecting IC components and rebuilding the eeg data: Some
> researchers try to be extra cautious and they try not to remove ICs that
> are "mixed", so as not to inadvertantly remove neural signal.
>
> Note that ICA is not a perfect method, and that there are often ICs that
> have both artifact and neural signal.
>
> See Luca's reaching site to get info and training on selecting/reviewing
> ICs, including a "practice" option that provides feedback about your
> classification. At minimum, I recommend that students do about 200
> classifications, review with an ICA-EEG expert, and then do another 200-300
> classifications.
>
> Remember that you also have to do cleaning before ICA, which does not seem
> to be one of the steps you listed.
> If you haven't had a chance to yet, please be sure to review the eeglab
> tutorial steps, practice with with eeglab tutorial data, and check out
> Makoto's pipeline suggestions.
>
>
> If you haven't yet, you should check out the various ICA classification
> plugins, such as MARA and SASICA, which should help you make a decision on
> your ICs.
>
>
>
>
>
>
>
>
>
> On Thu, Nov 9, 2017 at 3:54 PM, mahsa shalchy <mahsa.shalchy at gmail.com>
> wrote:
>
>> Dear Experts,
>>
>> I am trying to correct EEG data blinks and saccades using ICA, however,
>> in some cases (i.e. when the subject is double blinking), ICA finds
>> multiple eye related components.
>>
>> The problem is that except for the main blink component, other eye
>> contaminated ICs, have neural information and I can not easily discard them
>> ( please find an image of ICs here:
>> https://www.dropbox.com/sh/qjz2v3ke6zdr1j1/AABoSzG4s6ZyAlUz_vYC8slsa?dl=0
>> )
>>
>> I tried using PCA before ICA but it didn't seem to work.
>>
>> For the preprocessing I did the following steps before applying ICA:
>> Resampling, Filtering (0.1-40), re-referencing to average
>> mastoids,epoching.
>>
>> I highly appreciate your help on this problem.
>>
>> Many thanks,
>> Mahsa
>>
>> _______________________________________________
>> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
>> To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.uc
>> sd.edu
>> For digest mode, send an email with the subject "set digest mime" to
>> eeglablist-request at sccn.ucsd.edu
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20171113/296df911/attachment.html>