eeg reref

Robert Oostenveld r.oostenveld at FCDONDERS.RU.NL
Mon May 29 09:39:02 CEST 2006

Hi Giosue,

   cfg.reref         = 'yes';
   cfg.refchannel    = 'TP10';
you re-reference the data to TP10 only, i.e. TP10 will be the new
reference channel by itself and therefore it is flat (all zeros).

Assuming that TP9 is the other channel that you want to use, you
should do
   cfg.reref         = 'yes';
   cfg.refchannel    = {'TP9' 'TP10'};
to obtain the data referenced to linked mastoids.

If TP9 is the actual reference channel that was used in the
recording, and if you did not include TP9 in the recorded datafile,
you should also specify
   cfg.implicitref = 'TP9'
This will first add the channel TP9 to the data (which is all zeros,
since it is referenced against itself) and subsequently it will use
TP9+TP10 as the new reference. You can check afterwards: the sum of
the potential in TP9 and TP10 should be zero.


On 28 May 2006, at 20:49, Giosue Baggio wrote:

> After some thinking, another (perhaps more likely) possibility is
> that TP10 was also included in set of channels which now use TP10
> as reference. This would explain why it looks flat. If so, is there
> a way to exclude it from reref?
> Thanks,
> g.

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