[Eeglablist] removing ICA components

[Luisa Roeder]

Hi all,

I have been following the EEGLAB discussion list for a few weeks now and have been working through most of the tutorials and wiki pages but I am still a newbie to MATLAB, EEGLAB and analysing EEG signals in general. Hence, I have basic, newbie questions which I hope you can help me with.

I am trying to follow the analysis steps that are outlined in this paper:     Petersen, T.H., M. Willerslev-Olsen, B.A. Conway, and J.B. Nielsen, The motor cortex drives the muscles during walking in human subjects. The Journal of physiology, 2012. 590(Pt 10): p. 2443-52.
http://www.ncbi.nlm.nih.gov/pubmed/?term=1.%09Petersen%2C+T.H.%2C+M.+Willerslev-Olsen%2C+B.A.+Conway%2C+and+J.B.+Nielsen%2C+The+motor+cortex+drives+the+muscles+during+walking+in+human+subjects.+The+Journal+of+physiology%2C+2012.+590%28Pt+10%29%3A+p.+2443-52.

At the moment I am looking at a continuous dataset that contains 6 EEG and 6 EMG channels and that was recorded during a sustained muscle contraction of the leg. Eventually I also want to look at gait data but I am not there yet.
As outlined in the paper, I am trying to perform ICA (runica) on the EEG channels. After I ran the ICA, I want to remove unwanted components (in the gui) via Tools->reject data using ICA-> reject components by map. However, since I only recorded 6 channels (C3, Cz, C4, F3, Fz, F4) the head maps I receive only cover the region between the 6 electrodes but not the whole head. Also, when clicking on one component the top right panel that is supposed to show the activity of the component is empty.
Here is a link to 2 images: https://www.dropbox.com/sh/t5b8kmb9b9ce93e/AAC5VyeSEQbob0PTSiSZ61Ita

This does not provide sufficient information to be able to judge whether to keep or to discard a component.
What can I do to fix the problem? Is there another/better/more appropriate way to remove artefacts from my data than this approach? Or is the only way recording more channels (32+?) so that I can plot sufficient head maps?
Currently I use MATLAB R2012a and EEGLAB v10.2.5.8b.

Thanks so much in advance for your help!!
Kind regards
Luisa

Luisa Roeder | PhD researcher | Movement Neuroscience Program
Institute of Health and Biomedical Innovation & School of Exercise and Nutrition Science
Queensland University of Technology | 60 Musk Ave, Kelvin Grove, Brisbane, QLD 4059, Australia.
t: +61 7 3138 6428 | e: l.roeder at qut.edu.au<mailto:l.roeder at qut.edu.au>
w: www.ihbi.qut.edu.au/about/researchover/injury/movementNeuroscience.jsp<http://www.ihbi.qut.edu.au/about/researchover/injury/movementNeuroscience.jsp>
CRICOS No. 00213J

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