[Eeglablist] removing ICA components

Luisa Roeder l.roeder at qut.edu.au
Wed May 14 22:27:27 PDT 2014


Thanks, Steve, for your reply.
Yes, that is what I thought re the ICA amplitude per trial plot…
Re the head maps, I thought there may be another analysis approach; e.g. instead of rejecting components based on maps doing it somehow differently…

Cheers
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: 07 3138 6428 | m: 0427 469 478 | 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


From: politzerahless at gmail.com [mailto:politzerahless at gmail.com] On Behalf Of Stephen Politzer-Ahles
Sent: Thursday, 15 May 2014 1:17 PM
To: Luisa Roeder
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] removing ICA components

Hello Luisa,

As for the top right panel of that plot, what that plots is the ICA's amplitude per trial, and the ERP. So I imagine you can't get those when you're not using epoched data (although I haven't tried myself).

I'm not sure about the issue with the head maps; my hunch is that it might not be possible to get good topoplots without more channels, but hopefully someone else more familiar with that issue can give you some more input.

Best,
Steve


Stephen Politzer-Ahles
New York University, Abu Dhabi
Neuroscience of Language Lab
http://www.nyu.edu/projects/politzer-ahles/

On Thu, May 15, 2014 at 3:37 AM, Luisa Roeder <l.roeder at qut.edu.au<mailto:l.roeder at qut.edu.au>> wrote:
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<tel:%2B61%207%C2%A03138%206428> | 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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