I've collected EEG data using 24 channels system. Twenty-three channels (19 active EEG, 1 VEOG, 1HEOG, 1 right-earlobe) were referenced by left-earlobe, and one channel used for EOG bipolar (V-EOG referenced by H-EOG). I'm trying to clean my data using ICA.
My question, what is the minimum number of EEG channels that required to properly run ICA?
and, is it better to run ICA with all the channels (24) or i need to remove the bipolar EOG channel that not sharing the same common reference?
Thank you,
Could you say a bit more about what you are trying to accomplish with your ICA? Some people use ICA as an artifact removal technique to extract muscle or blink artifacts from their scalp channels, others will use ICA to extract task- or experiment-related brain data like ERP components, etc.
From what I know, there isn't really a minimum number of channels necessary to run an ICA, but you will only get back as many ICA components as you have channels. So, if you entered all 24 of your channels, you have the potential to examine 24 ICA components. The more channels you have, the more you can "dissect" your data into unique aspects.
If you are looking at the brain data, I would recommend NOT including the EOG channel. ICA is dependent on commonalities in your data, and if the EOG is not referenced the same way as your scalp sensors then it will likely throw off your results and introduce measurement error.
Thank you Dr. Brittany K. Taylor,
Actually, I am trying to use ICA to clean my data form stereotype artifacts such as eye blink.
Excellent, thanks for the information. There is some very helpful, detailed information in an analysis pipeline walkthrough at this site:
https://sccn.ucsd.edu/wiki/Makoto%27s_preprocessing_pipeline#General_tips_for_performing_ICA_.2806.2F26.2F2018_updated.29
In short, the recommendation is to exclude your bipolar eye channel from the ICA analysis. If you were using the individual eye channels and referenced them to the same reference as the rest of your scalp channels, then you could include them in your ICA.
One other note to consider in your analyses: you might think about creating an averaged reference of the left and right earlobe channels and using that as your reference for scalp sites. Some experimental designs have historically used a single earlobe reference (e.g., auditory sensory gating), however you may find an unwanted bias in the noise correction in your data if you only reference to the noise captured on one side of the head. In other words, you may remove more extraneous environmental noise from half of your scalp sites than you remove from the other half. Using the averaged earlobe reference may help clean your data.
Best of luck with your analyses!
- Badges
- Science topic
- Similar topics
- Psychology