[Eeglablist] ICA (X-Y) or ICA(X)-ICA(Y)?

[Makoto Miyakoshi]

Dear Akshay,

> 1. ICA (ERP to X- ERP to Y)

We've been taking this approach so far. Below I forward a recent
communication with my collaborator.

One of the assumptions of ICA applicaiton on EEG is that there be fixed
spatial relation between EEG sources and recording electrodes. We also take
it granted that the brain has functional mapping that does not change
throughout the experiment. The EEG sources may show modulation in
activities, but not their spatial locations. We assume different ICA is
needed only when electrode cap is moved/removed.

I assume that the same system correspond differently depending on
stimulation, rather than different system emerges every time you change the
stimulation. This is theoretically because functional segregation of the
brain is far from independent but they highly interact with each other--you
can find this classical argument in this Karl Friston's paper:

Friston KJ, Price CJ, Fletcher P, Moore C, Frackowiak RS, Dolan RJ. The
trouble with cognitive subtraction. Neuroimage. 1996 Oct; 4(2) 97-104.

Makoto

On Thu, Sep 3, 2015 at 7:56 PM, Akshay Maggu <akshaymaggu86 at gmail.com>
wrote:

> Hi list,
>
> I have an experiment where I look at difference wave. As I am using the
> STUDY design, what method should be appropriate in terms of preparing the
> data before feeding in the STUDY:
>
> 1. ICA (ERP to X- ERP to Y); or
> 2. ICA(ERP to X)-ICA(ERP to Y)
>
> where X and Y are 2 different events and collected in the same block.
>
> Thanks,
> Akshay
>
> --
> Akshay Raj Maggu,
> PhD Candidate,
> Laboratory for Language, Learning and the Brain,
> Department of Linguistics and Modern Languages,
> The Chinese University of Hong Kong,
> Hong Kong.
> Webpage: http://www.cuhk.edu.hk/lin/new/people/students/maggu/
> *Save trees.. Save life! Please don't print this email unless you really
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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