[Eeglablist] Reference point location and Cleanline issue

[Makoto Miyakoshi]

> Cleanline unfortunately did not work, I used it at 50Hz and at 100Hz but
it did nothing, the interference remains for both frequencies.

By the way, did you use the option 'newversion', 1? It works more
definitively with this option on.

Makoto

On Wed, Jan 24, 2024 at 4:05 PM Deepa Gupta via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hi Chester,
>
> Sorry for the delayed reply as I got caught up. Below are my
> responses/comments in blue to your questions. Hope that helps
>
> Sincerely
> Deepa Gupta <
> https://urldefense.com/v3/__https://www.linkedin.com/in/deepaguptaresearcher/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-Q9LTdWb0$
> >
> Postdoc Scholar, SCCN <https://sccn.ucsd.edu/>, SDSC <
> https://www.sdsc.edu/>
> , INC <https://inc.ucsd.edu/index.php>, UCSD <https://ucsd.edu/>
> Ph.D. , Dr. Choa's Lab <
> https://urldefense.com/v3/__https://blogs.cs.umbc.edu/choalab/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-Qk75Im4Q$
> >, CSEE
> <
> https://urldefense.com/v3/__https://www.csee.umbc.edu/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QKDyql7o$
> >, UMBC <
> https://urldefense.com/v3/__https://www.umbc.edu/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QPWOXxzc$
> >
>
>
> On Sun, Jan 21, 2024 at 11:10 PM chester20080 <chester20080 at yahoo.gr>
> wrote:
>
> > Thank you for the prompt response.
> >
> > I'm in Europe, so the interference here is at multiples of 50Hz and the
> > signal was recorded on the scalp externally. - okay then yes we are
> > seeing harmonics at 50Hz. you may adjust the parameters accordingly.
> > consider inputting the parameter in there as [50 100 150] or further
> > depending on your Nyquist frequency. Cleanline unfortunately did not
> > work, I used it at 50Hz and at 100Hz but it did nothing, the interference
> > remains for both frequencies - please consider changing the parameters. I
> > tried that along with applying it more than once and it reduced it
> > considerably although not completely but enough to work with. I forgot to
> > mention that the patient is at resting state and is considered healthy.
> > Perhaps I should low pass at 75Hz or even at 40-50Hz? - depends on your
> > scientific investigation. I can't say here for sure. we can connect to
> > discuss or try coming for EEGLAB workshop :) . I guess I don't expect any
> > gamma activity at resting state - not necessarily. there is a lot of
> > literature suggesting gamma coupled with theta. A random example: Barry,
> > Robert J., et al. "Resting-state EEG gamma activity in children with
> > attention-deficit/hyperactivity disorder." *Clinical neurophysiology*
> 121.11
> > (2010): 1871-1877.. Alternatively, could I just use a notch for 50Hz (as
> > a bandwidth fir @ 48-52Hz)? - Under our senior expert Scott's kind
> > supervision, I learned that it (notch filter) could potentially take a
> lot
> > of information out of your EEG data. Under our expert Makoto's kind
> > mentorship, I learned that notch filter can take out the line noise.
> > Ultimately, post a lot of time-taking thinking, I went with my decision
> to
> > remove the line noise on my data/data given to me with the method that I
> > chose as I realized that I am the best closest judge of my scientific
> data
> > and investigation. Basically, post all the advisory, I'd go with the
> > final judgment of the investigator who is looking at the data at the
> > closest as that person is the one investigating/handling it/your EEG data
> > while following the right principles. So, manage that with care and best
> > of luck for your EEG fun. cheers.
> >
> > For the reference, G2 is not included in the file, in the lookup, so even
> > if I name an additional channel G2 and click on look up locs, it cannot
> > load the coordinates since this point is not a standard besa 4-shell
> dipfit
> > point I think, and I don't have any locations file to use as source. -
> I'd
> > suggest you to please consider creating an EEGLAB issue about this.
> However,
> > could I use Cz itself as the reference point instead, since G2 (the
> actual
> > reference point for which I don't have any other data/info) is so close
> to
> > Cz? And use the procedure described in the link to append another Cz
> > channel only to use it as reference? - sure. yes. good thought. In case I
> > do just that, do I need to run average re-referencing based on Cz as well
> > or just set Cz as the reference channel in the Channel locations window?
> -
> > depends on your data. Ideally, re-referencing once should be okay but you
> > could be needing to do it twice in certain situation - hopefully the data
> > is not that wierdly bad - in one of my case it sadly was - just depends.
> > Another tip, you may have to see data scroll , spectrum etc before and
> > after your applied steps and make the final judgment for your final
> pipeline
> > . Keep in mind that re-referencing with a channel (CZ here) would have
> > you lose one channel's worth of data whereas that's not the case with
> > average re-referencing. So, you could recover the data (here the CZ
> > channel's data) by averaging post referencing with CZ channel's data.
> hope
> > that makes sense. please refer to the documentation again that i
> > previously provided if still needed.
> >
> https://urldefense.com/v3/__https://eeglab.org/tutorials/05_Preprocess/rereferencing.html__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QY0j8Y-c$
> >
>
> >
>
> > Thank you again in advance. - very welcome. all the best. Deepa
> > Στις Δευτέρα 22 Ιανουαρίου 2024 στις 02:45:16 π.μ. EET, ο χρήστης Deepa
> > Gupta <deepag1 at umbc.edu> έγραψε:
> >
> >
> > Hi Chester,
> >
> > Thankyou for using EEGLAB. Please see the responses below:
> >
> > regarding your query#1 - are you not seeing a harmonic at 60Hz? If not
> > then yes, it could be harmonic. It also depends on where this was
> recorded.
> > you may preferably consider using cleanline (more than once if needed)
> > among other possible techniques.
> > regarding your query#2 - Please check this if you haven't already:
> >
> https://urldefense.com/v3/__https://eeglab.org/tutorials/05_Preprocess/rereferencing.html__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QY0j8Y-c$
> and check
> > for *Look up locs*
> > Basically you would need to go to Edit -> channel locations - then please
> > append channel as per the documentation if you must followed by Look up
> > locs to get the coordinates for G2 and then have it as set reference.
> Once
> > that's done, you may re-refer by going to Tools → Re-reference the data
> >
> > Hope that helps
> > Sincerely
> > Deepa Gupta <
> https://urldefense.com/v3/__https://www.linkedin.com/in/deepaguptaresearcher/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-Q9LTdWb0$
> >
> > Postdoc Scholar, SCCN <https://sccn.ucsd.edu/>, SDSC
> > <https://www.sdsc.edu/>, INC <https://inc.ucsd.edu/index.php>, UCSD
> > <https://ucsd.edu/>
> > Ph.D. , Dr. Choa's Lab <
> https://urldefense.com/v3/__https://blogs.cs.umbc.edu/choalab/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-Qk75Im4Q$
> >, CSEE
> > <
> https://urldefense.com/v3/__https://www.csee.umbc.edu/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QKDyql7o$
> >, UMBC <
> https://urldefense.com/v3/__https://www.umbc.edu/__;!!Mih3wA!BLObfypm9iQeVY1LfATL1hFE7qbBD6KPkBPTMn7Ju7RUscVWEK23YYTekDigdYOjC6QWCz0IYxRBUg-QPWOXxzc$
> >
> >
> >
> > On Sun, Jan 21, 2024 at 2:30 PM chester20080 via eeglablist <
> > eeglablist at sccn.ucsd.edu> wrote:
> >
> > Hello all,
> > I am a postgraduate student in biomedical engineering and this is my
> first
> > time analyzing EEG signals in eeglab. The recording is from a healthy
> > person at resting state. The montage is based on the International 10-20
> > system and has 19 electrodes (no location file, the locations are
> > automatically recognized with BESA 4shell dipfit). The recording was done
> > with reference to point G2 set 1 cm under Cz at a sampling rate
> (frequency)
> > of 256 Hz.
> >
> > 1) When I plot the spectrum I see two big peaks at 50Hz and 100Hz, while
> > the 100Hz is higher than 50Hz. Is this harmonic power line interference?
> > The problem is that the cleanline plugin does not remove this artifact at
> > all, it does nothing, the interference remains at both frequencies
> > unchanged, unattenuated.
> >
> > 2) The second problem is that I don't know how to use the information
> > about the reference point G2 located 1cm under Cz. I have Cz coordinates
> in
> > both polar and cartesian. "Under" means inside the brain vertically so Z
> > coordinate needs to decrease by 10mm or does it mean externally following
> > the spherical curvature of the head or something, in which case both X
> and
> > Z change, but then it gets very complicated, what are the exact
> coordinates
> > for G2? And then I have to create such a channel manually, insert the G2
> > coordinates and run re-reference? I'm lost.
> >
> > Can you please help me? Thank you in advance.
> > _______________________________________________
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