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Bug 3056 - lcmv beamformer source solution mismatch topography

Reported 2016-01-31 17:53:00 +0100
Modified 2019-08-10 12:33:17 +0200
Product: FieldTrip
Component: inverse
Version: unspecified
Hardware: PC
Operating System: Mac OS
Importance: P5 normal
Assigned to:
Depends on:
See also:

Philipp Ruhnau - 2016-01-31 17:53:07 +0100

Created attachment 770 script and example image Dear ft-developers, I've noticed something strange and I cannot figure out what the issue is (see example screen shots and analysis pipeline aattached). I'm not entirely sure this is a bug, but given the recent problem with localspheres maybe this is related? as can be seen in my screenshot in the attachment, when I beam an erf using the lcmv method with a common filter I get very odd source solutions. I noticed this on the group level (where actually my effect was inverted in polary, and sort of medial). the paradigm is super simple (hit vs. miss of a threshold visual stimulus on the right screen side) with hundreds of trials, thus there should be a quite clear erf for hits, left lateralized. but as i said on group level i get hit < miss and more something medial or, as for the example subject frontal activity. I tried numerous things to name those I still remember: leadfield normalisation, regfactor (0/5/10), creating an average from the mom field (which gives interestingly enough a quite different solution but still an odd one), different grids, fixedori, separate filters, longer covariance time window, solutions based on gradiometers/magnetometers/both, i even calculated the covariance by hand, but still all the same. I think that, if there is a problem and I didn't just kept a typo, then that the problem is somewhere in parts of the code that I do not have the mathematical knowledge to understand.... only observation is that it seems the source reconstructions of both conditions are dominated by the filter. the covariance/data don't seem to do much. I put the data and vol/mri in my dropbox: sorry for these large data, but I haven't figured out how to simulate good ERF data for gradiometers.... I was considering writing this to the list first, and apologize if it is a mistake on my side. Best Philipp p.s.: the data in the dropbox contain gradiometers only, to reduce space

Philipp Ruhnau - 2016-01-31 18:00:59 +0100

sorry, submitted twice, and cannot figure out how to delete *** This bug has been marked as a duplicate of bug 3057 ***

Robert Oostenveld - 2019-08-10 12:33:17 +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 on