[Eeglablist] Inquiry about Importing cnt file into MATLAB

SAMUEL SUI LUNG SZE u3564255 at connect.hku.hk
Tue Dec 28 08:43:23 PST 2021


Dear all,

Hello, everyone. I would like to ask about importing CNT files. I have
difficulty importing cnt files "properly" into Matlab. I have tried two
ways, and I do not seem to do this correctly in either way.

Regarding the *first* way, I go to "File" -> "Import data" -> "Using EEGLAB
functions and plugins" -> "From Neuroscan .CNT file". For the dialogue
"Load a CNT dataset", I leave the setting as it is:

https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_1JNuprB2ZbHnPFs86qlOIlhBK3opI-5FMXX_view-3Fusp-3Dsharing&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=smWDMM697QfkjvdeeOoBs51YrNCotHMCj5pnqwkLtVZXsLLNe6bDgd9vWfOhByWk&s=PGA3wKMKQmHZuLQ4qEaskW00YbcG1ni3oEZUMiHVT5Y&e= 

On the homepage of EEGLAB, I can see the details of the EEG dataset.

https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_1x1iNwWmVFWyk0t6jLfAsShbmiXhjILN7_view-3Fusp-3Dsharing&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=smWDMM697QfkjvdeeOoBs51YrNCotHMCj5pnqwkLtVZXsLLNe6bDgd9vWfOhByWk&s=C92DgrwgIcm_CHtMFr0P-C5xYIccwaL02OUizfqqF4E&e= 

However, when I go to "Plot" -> "Channel data (scroll)", though the
channels and their labels are shown on the y-axis clearly, I do not see any
EEG data in the time-domain plot. To be specific, I do not see any
fluctuation of EEG signals in each channel.

https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_10701oAA6UT7-2DMysNbgeCW0onPm1fls2x_view-3Fusp-3Dsharing&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=smWDMM697QfkjvdeeOoBs51YrNCotHMCj5pnqwkLtVZXsLLNe6bDgd9vWfOhByWk&s=_7OATDvYsD_3U6507SxvGKYB5G6mITaE2lcRTcJaBEE&e= 



As for the *second* way, I run the code below to import the EEG dataset
into Matlab:

EEG1 = pop_loadcnt('/Users/samuelsze/Desktop/L1/Acquisition_practice.cnt' ,
'dataformat', 'auto', 'memmapfile', '');



Then, I plot the dataset "EEG1" using the code below,

plot(EEG1.times(:), EEG1.data(:,:))


and the resulting plot is as below:

https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_1QJqg4HA5ztwUhtJY2F3RiPLv3GzWSNwy_view-3Fusp-3Dsharing&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=smWDMM697QfkjvdeeOoBs51YrNCotHMCj5pnqwkLtVZXsLLNe6bDgd9vWfOhByWk&s=8m2-OCvwL_CDFZ9ySMRFhUFbxAGjQ3Q7A1MIxYGOvH0&e= 



My gut tells me that I may have used the wrong ways to import the CNT file
because when I import the same CNT file to, and visualise it on Brainstorm,
I have a seemingly more reasonable plot:

https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_1uZH4kx-2DKkV-5F3oLcsl5OBNhg52jOUXzoJ_view-3Fusp-3Dsharing&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=smWDMM697QfkjvdeeOoBs51YrNCotHMCj5pnqwkLtVZXsLLNe6bDgd9vWfOhByWk&s=B4UEHAelmvN3FUqXJN1j1Hl4uZkORwIBCd-fP4UTGlA&e= 

As I think EEGLAB and ERPLAB are more user-friendly (It is a personal
preference), I would like to learn from you folks how I can correctly
import the CNT file into EEGLAB and MATLAB. Could you please help me with
that? Thank you in advance!

Best regards,
Samuel


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