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Bug 1630 - applying average mastoid reference derivation to EEG data

Reported 2012-08-06 12:55:00 +0200
Modified 2019-08-10 11:56:25 +0200
Product: FieldTrip
Component: core
Version: unspecified
Hardware: PC
Operating System: Windows
Importance: P3 normal
Assigned to:
Depends on:
See also:

Lilla Magyari - 2012-08-06 12:55:28 +0200

hi, I wanted to apply average mastoids reference derivation on my EEG data. The data recorded at each channel is already referenced to the left mastoid (LM), and now I would like to include also the right mastoid in the reference, so I have to re-reference my data. But when I use this configuration of ft_preprocessing: cfg.reref='yes'; cfg.refchannel='RM'; it just simply subtracts RM from each data-point: a'=a-RM. However, I think this is not correct because RM has been already referenced also to LM. Therefore, only RM/2 should be subtracted from each data-point (a'=a-(RM/2)). I can circumvent this problem with using the montage option, but I guess it would be nice to explain this also to other users. Lilla

Lilla Magyari - 2012-08-06 14:39:24 +0200

(In reply to comment #0) I just have discussed this with Robert. It can be done like this: cfg=[]; cfg.implicitref='LM'; cfg.refchannel={'RM','LM'};

Lilla Magyari - 2012-08-06 14:40:02 +0200

so, I close this.

Robert Oostenveld - 2019-08-10 11:56:25 +0200

This closes a whole series of bugs that have been resolved (either FIXED/WONTFIX/INVALID) for quite some time. If you disagree, please file a new issue describing the issue on