[FieldTrip] data visualization: scale?

[Nathalie George (UPMC)]

Dear all,

we are processing EEG data with Fieldtrip and we use ft_databrowser to 
visualize our data (typically, for example, to review data and check if 
they have been well corrected by ICA, or to check if they are remaining 
artefacts after some correction). These are continuous or epoched raw or 
ICA-corrected EEG data recorded on multiple (128) channels.

I have a problem which is that I find it very hard to know what is the 
scale of data visualization. For example: ylim = [-50, 50] seems to 
correspond to some arbitrary unit which does not represent the same 
"height" on screen depending on how many channels I am displaying; hence 
fixing ylim does not help. I have not found the way to know to how much 
height or "cm" my y scale corresponds.

Can you help me with this?

thank you very much in advance,

best

nathalie george

Le 18/03/2021 à 10:32, H L a écrit :
> Dear all,
>
> I'm a beginner in the fieldtrip use.
> I have a dataset of 6 different subjects. Before analyzing this 
> dataset, of course I wanted to reject any artifact. I did it through 
> two way:
> 1) first I used the ft_databrowser() function to do it manually as 
> follows:
>
> >> for i = 1 :numel(dataEEG)
>
> >> cfg = []
>
> >> cfg.channel = ‘all’
>
> >> cfg.viewmode = ‘butterfly’
>
> >> artifact = ft_databrowser(cfg, dataEEG(i))
>
> >> end
>
> So I selected the crunches of the data letting me think that it could 
> be artifacts
>
> 2) second, I wanted to do it using the ft_rejectvisual() function with 
> the 'summary' method option
>
> >> for i = 1 :numel(dataEEG)
>
> >> cfg = []
>
> >> cfg.method = ‘summary’
>
> >> artifactSummary = ft_databrowser(cfg, dataEEG(i))
>
> >> end
>
> Now I would like to compare the both dataset without artifact to see 
> if what I rejected with ft_databrowser() and ft_rejectvisual() 
> functions are comparable. *However, I really do not know how to print 
> the plots of the new datasets without artifacts generated by both 
> method to compare it visually. Would you know how to do it?*
>
>
> Thank you so much for your kind help!
>
>
> Best regards!
>
>
> Hugues
>
>
> _______________________________________________
> fieldtrip mailing list
> https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> https://doi.org/10.1371/journal.pcbi.1002202

-- 

--
Nathalie GEORGE, DR CNRS
Equipe Experimental Neurosurgery
Directrice Scientifique du Centre MEG-EEG

Institut du Cerveau et de la Moelle Epiniere (ICM)
UMR 7225 / UMR_S 1127, Sorbonne Université / CNRS / INSERM
GHU Pitié-Salpetriere
47, Bd de l'Hopital
F-75651 PARIS Cedex 13

tel: +33(0)1 57 27 43 79
fax: +33(0)1 57 27 47 93
e-mail:nathalie.george at upmc.fr

http://icm-institute.org/fr/
***********
Si tout ici-bas était excellent, il n'y aurait rien d'excellent.

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