[Eeglablist] Inquiry about Importing cnt file into MATLAB

SAMUEL SUI LUNG SZE u3564255 at connect.hku.hk
Wed Dec 29 21:47:11 PST 2021


Dear Mr Cannard,

Thank you for your help. The data look fine after being rereferenced and
high-pass filtered.

Best regards,
Samuel

On Thu, Dec 30, 2021 at 12:51 PM Cedric Cannard <ccannard at protonmail.com>
wrote:

> Hi,
>
> Can you do an average reference and high pass filter at 1 Hz (in Tools
> menu) and send another screenshot?
> Regarding the blank plot, that’s normal, select “remove DC offset” in the
> plot menu (or after the lowpass filter), and the signal should become
> visible.
>
> You can also send a link to the file and I’ll take a look.
>
> Cheers,
>
> Cédric
>
>
> On Tue, Dec 28, 2021 at 08:43, SAMUEL SUI LUNG SZE via eeglablist <
> eeglablist at sccn.ucsd.edu> wrote:
>
> 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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