About ICA cleanning and higher voltage

Discussions
1

Hello!
¡:D!

I was cleaning up an EEG file using ICA, when I noticed some curious thing happening:

darICA
darICA1358×649 85.1 KB

File "A" is the original EEG, which has some noise in the Cz lead signal, so I removed it with ICA,
File "B" is the cleaned EEG, it seems to be the same, but now, the voltage has changed: the voltage of file B is higher than the original, so I had to rescale it to get the same view,

is it expected?
How can I restore the EEG signal to its original voltage level?

Thanks in advance.

2

is it expected?

No, this is not expected.
It is more a diminution of the amplitude that is expected, when you remove components.

It is not possible for me to investigate your question as this observation can come from many things:

  • the export from Brainstorm to EDF (which is never recommended - use the BrainVision format instead, which can represent floating point values)
  • the EDF reader from this software you are using
  • the actual cleaning with ICA

The only item for which I will provide through this forum is the last one.
If you observe any difference in amplitude IN BRAINSTORM after removing some ICA components, please report it.

3

I see!
Thanks for the reply
:open_mouth: