[Eeglablist] 16 Hz artifact with lower harmonics in data

[Cedric Cannard]

Hi,

I have seen similar 16 Hz artifactual peaks before, but this was due to the galvanic skin response (GSR) electrodes I was using simultaneously to the 64 EEG channels (Biosemi system).

I don't see mention of GSR electrodes in your initial email so this might be irrelevant, but my guess is that you are encountering something similar (i.e., Common mode interference, mainly the DRL and potentially an alternating current at 16 Hz involved in your referencing system), here are two blog posts with a lot of very valuable information:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.biosemi.nl_forum_viewtopic.php-3Ft-3D831&d=DwIFaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=gF7HSLnIMfk8fT8vjg9VzM5J8EFH3sWi7KfgPHPTQgq2Ab2mAH7MOlY3JgCRYEDM&s=wcNY6BH6K0of5XKgKmUa_fw7eyPqlLsHdS3oIshBzGE&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.biosemi.nl_forum_viewtopic.php-3Ft-3D1248&d=DwIFaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=gF7HSLnIMfk8fT8vjg9VzM5J8EFH3sWi7KfgPHPTQgq2Ab2mAH7MOlY3JgCRYEDM&s=d9Ue9nEUIaNPHTXKAxqCQRH6ozZvK5EqD3rkl7JnnCY&e= 

Hope this helps and good luck!

Cedric


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, March 31, 2022 3:20 AM, Malte Anders <malteanders at gmail.com> wrote:

> Dear all,
>
> We are currently trying to record EEGs on the open brain of certain animals
>
> -   so no "standard" human recordings. The gold electrodes are placed
>     directly on the brain, without any conductive gel applied.
>
>     We are encountering a strange ~16 Hz artifact, with harmonics around ~10.x
>     Hz and ~5.x Hz, see these images:
>     https://urldefense.proofpoint.com/v2/url?u=https-3A__ibb.co_NKMcrf0&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=c88_VOjmnuVwvN-A41WN_LrcUXdxqhHwgozv6g_vBGXNTPB1AS0LrJkqDp8M8B44&s=E8I2mkOB0AmaOPUEUXwPZvKu-BkYWuzhow82gl11YCg&e=
>     https://urldefense.proofpoint.com/v2/url?u=https-3A__ibb.co_Z8zkCpp&d=DwIBaQ&c=-35OiAkTchMrZOngvJPOeA&r=kB5f6DjXkuOQpM1bq5OFA9kKiQyNm1p6x6e36h3EglE&m=c88_VOjmnuVwvN-A41WN_LrcUXdxqhHwgozv6g_vBGXNTPB1AS0LrJkqDp8M8B44&s=haiZvyK3aT-jVpA4wpHVfjQQrPRs1O0cx88EnN9NitE&e=
>
>     Anybody ever saw artifacts in these frequency ranges? I am trying to narrow
>     down if those artifacts stem from our recording setup itself (maybe bad
>     impedance between the brain and the measuring electrode?), or from any
>     other external hardware in our recording setup.
>
>     Any help is much appreciated!
>     Malte
>
>
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</malteanders at gmail.com>