[Eeglablist] ICA question

[Ahmad, Jumana]

Dear EEGlab.

For data rank reasons, I interpolated and average referenced after ICA, using runica. When re-referencing I deleted the ICA activation matrix and the ICA weights, because of course I now have interpolated channels which do not have ICA weights associated with them.


I only wanted to do ICA for eye blink rejection, and it worked perfectly and I did not have any ICA corruption (trade offs or rank deficiency). I compared the data before and after ICA and the level of noise was the same.


I am working with an extremely large dataset and do not ideally want to re-do these steps, especially because I am mainly working with raw channel ERP data.


However, for future analysis, if I did want to work with component data, could I re-run ICA for a second time, this time on the Chanel data where ICA blink components have been removed, and where the interpolated electrodes and the new reference implemented (this data should already be clean from blinks etc).


Overal this would look like:


Identify noisy channels

Run ICA on clean channels

Interpolate electrodes to give the same 60 electrodes per person

Average reference to the 60 electrodes

Compute ERPs on channel data

Then re-run ICA, and do any further analysis on component data.



Please let me know if you can see any issues with this. I very much appreciate any advice.

Best wishes,

Jumana


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Jumana Ahmad
Post-Doctoral Research Worker in Cognitive Neuroscience
EU-AIMS Longitudinal European Autism Project (LEAP) & SynaG Study
Room M1.26.Department of Forensic and Neurodevelopmental Sciences (PO 23) | Institute of Psychiatry, Psychology & Neuroscience | King's College London | 16 De Crespigny Park | London SE5 8AF

Phone: 0207 848 5359| Email: jumana.ahmad at kcl.ac.uk<mailto:antonia.sanjose at kcl.ac.uk> | Website: www.eu-aims.eu<http://www.eu-aims.eu/> | Facebook: www.facebook.com/euaims<http://www.facebook.com/euaims>

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