[Eeglablist] Should Average Reference Include Eye Channels?

[Matthew Stief]

Thank you very much for this Scott.  I am personally not dealing with
bipolar eye channels, my eye channels have a common reference with the rest
of the scalp electrodes.  Can I assume from your post that you agree with
Alejandro that these can be included into the average reference with no
worries about the greater noise present in them having negative effects on
the quality of the average reference?

-Matthew Stief


On Sun, Feb 19, 2012 at 11:26 PM, Scott Makeig <smakeig at gmail.com> wrote:

> However, performing average reference on the common reference channels,
> and then combining these with the bipolar channels into the ICA training
> matrix is possible -- since all the signals are linearly related to the
> independent source activations.
>
> However, in this case the IC scalp maps may have a discontinuity between
> the  eye and scalp channels, since they do not share a reference.  Removing
> the bipolar eye channels from these maps involves performing a
> pseudo-inverse on the IC map matrix, however, which may introduce some
> degree of inaccuracy ...
>
> In practice, ICA typically picks up eye activities very well from their
> frontal scalp channel projections -- so I'd recommend using the extra
> channels for any other common-reference channel positions of interest, and
> not for bipolar eye channels.
>
> Scott Makeig
>

-- 
_________________________________________________________________
Matthew Stief
Human Development | Sex & Gender Lab | Cornell University
http://www.human.cornell.edu/HD/sexgender


Heterosexuality isn't normal, it's just common.
-Dorothy Parker
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