[Eeglablist] For Marjan

[Makoto Miyakoshi]

Dear Madam Marjan,

> First of all, I used the ASR section of EEG Lab and rejected the bad
channels, and after that I applied an interpolate channels and then average
reference to my data as you said on your pipeline. But, unfortunately, when
I wanted to run Amica to my data, the number of components were less than
channels(the number of channels were 14 and components were 2 or 3). I
struggled with this issue for a long time but I failed to find an effective
solution.

That is because when scalp electrodes were interpolated, your data rank
dropped to the number of the remaining electrodes. ICA knows how many
electrodes were there before interpolation by calculating the data rank.
See this article for more information.

https://sccn.ucsd.edu/wiki/Makoto%27s_preprocessing_pipeline#What_is_rank.3F_.28Updated_06.2F06.2F2016.29

> I also investigated the amount of EIG value, but I have no idea which
change I should apply to my data to obtain the required component's amount.
I was wondering if you could help me with my problem.

See these articles.
https://sccn.ucsd.edu/wiki/Makoto%27s_useful_EEGLAB_code#How_to_avoid_the_effect_of_rank-deficiency_in_applying_ICA_.2803.2F31.2F2021_added.29
https://sccn.ucsd.edu/wiki/Shannon%27s_ICA_rank_project

Makoto



Original message:
%%%%%%%%%%%%%%%%%%%%%%%%
Dear Sir Makoto
I would appreciate it if you could guide me about the problem I have with
the EEG lab. First of all, I used the ASR section of EEG Lab and rejected
the bad channels, and after that I applied an interpolate channels and then
average reference to my data as you said on your pipeline. But,
unfortunately, when I wanted to run Amica to my data, the number of
components were less than channels(the number of channels were 14 and
components were 2 or 3). I struggled with this issue for a long time but I
failed to find an effective solution. I do not know if the problem is
because of the W (Weight matrix) or another reason. I also investigated the
amount of EIG value, but I have no idea which change I should apply to my
data to obtain the required component's amount. I was wondering if you
could help me with my problem.
Best regards
Marjan