[FieldTrip] ICA: eeglab and fieldtrip

Stephen Whitmarsh stephen.whitmarsh at gmail.com
Mon Mar 31 22:10:36 CEST 2014


Hi Aaron (i see Stephen just wrote a similar response)

Those component topoplots look pretty good to me. In the FT one, I would
say the first and third have a good change of being related to eyeblinks,
and the fifth and twenty-fifth to eye-movements.
However, you should really look at the timecourses to identify them as
related to saccades and blinks, and by comparing them with your EOG
recording.

Although each ICA will *always* give you different results (if you don't
specifiy the random seed), to make them more comparable you could add the
EOG channel to the layout.

Cheer,
Stephen


On 31 March 2014 22:08, Stephen Politzer-Ahles <spa268 at nyu.edu> wrote:

> Hello Aaron,
>
> This doesn't, answer the rest of your questions, but... In your attached
> Fieldtrip image, component 1 does look like a likely blink component to me?
>
>
>
> Stephen Politzer-Ahles
> New York University, Abu Dhabi
> Neuroscience of Language Lab
> http://www.nyu.edu/projects/politzer-ahles/
>
>
> On Mon, Mar 31, 2014 at 11:52 PM, <fieldtrip-request at science.ru.nl> wrote:
>
>>
>> Message: 2
>> Date: Mon, 31 Mar 2014 14:51:51 -0500
>> From: Aaron Hanford <aharown at hotmail.com>
>> To: "fieldtrip at science.ru.nl" <fieldtrip at science.ru.nl>
>> Subject: [FieldTrip] ICA: eeglab and fieldtrip
>> Message-ID: <BLU184-W8ABD13D8D59439530A857A3630 at phx.gbl>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Hi,I'm resending this with the figures turned into jpgs so it's not
>> oversize...anyway, so I'm somewhat new to both fieldtrip and eeglab
>> (although much more so to fieldtrip).  I'm trying to figure out the
>> following:
>>
>> On the exact same dataset, I did the following two things:
>> 1) in eeglab, I just chose Tools -> Run ICA with default settings.
>> Then, starting over with the original raw data:
>> 2) In fieldtrip I ran the following: data =
>> eeglab2fieldtrip(EEG,'preprocessing','none');cfg = [];cfg.method =
>> 'runica';[comp]=ft_componentanalysis(cfg,data);layout =
>> 'C:\Users\aharown\Desktop\fieldtrip-20140126\template\layout\easycapM17.mat';cfg.component
>> = [1:31];cfg.layout = layout;ft_topoplotIC(cfg,comp);
>> In both cases I then plotted the 2-D component maps, attached.
>> So my question is, why are these results so completely different?  The
>> fieldtrip results don't look right at all, in that for instance they don't
>> obviously identify a blink component (note that in this dataset, there is
>> only one electrode placed near the right eye, not the left).  I did this a
>> handful of times and got the same sort of big differences.  Am I doing
>> something wrong or what?
>>
>> I actually think the cap file seems incorrect, but I've been assured by
>> my PI that it's correct, so .... is there another likely answer?
>> Thanks,
>> Aaron
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