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Bug 2881 - Topographic plotting for fNIRS data not possible

Status ASSIGNED
Reported 2015-04-24 13:40:00 +0200
Modified 2017-09-21 09:07:55 +0200
Product: FieldTrip
Component: external
Version: unspecified
Hardware: PC
Operating System: Windows
Importance: P5 normal
Assigned to: Jörn M. Horschig
URL:
Tags:
Depends on:
Blocks: 28822914
See also:

Jörn M. Horschig - 2015-04-24 13:40:54 +0200

In contrast to EEG, NIRS channels should be equidistant in absolute terms, and not like e.g. EEG in relative distances to anatomical landmarks. Also, NIRS channel configurations are not designed to cover the whole head and usually defined in 2D. NIRS channels are mostly defined in some egocentric coordinate system, with a certain optode being placed at (0/0), and all other optodes are defined with respect to that origin. Topographic plotting, however, requires some mapping to an anatomical landmarks or an EEG channel. A proper strategy how to best deal with this and the various rationales out there needs to be developed. Thus, literature needs to be required on how optode placement is most commonly described (most likely, wrt the EEG 10-20 system). Then, a clean way to implement with needs to be found.


Jörn M. Horschig - 2015-04-24 13:42:02 +0200

hmm, something went wrong in the last paragraph... Thus, literature needs to be *reviewed* on how optode placement is most commonly described (most likely, wrt the EEG 10-20 system). Then, a clean way to implement *this* needs to be found.


Jörn M. Horschig - 2015-04-24 13:54:12 +0200

suggestion from Robert: add brain picture as a overlay, paint optode positions on top and visualize channel activity in between the optodes as a colored sausages


Matteo Caffini - 2015-11-05 13:30:37 +0100

A possibility could be to have both the flat probe geometry (whatever the coordinates system) and a few anchor points (in the 10-20 coordinates system) and then let a dedicated function calculate the projected probe in the layout plot space by translating, rotating, scaling and "bending" the flat probe geometry.


Robert Oostenveld - 2017-09-21 09:07:55 +0200

Janny (now also CC) just triggered me to think about this and to look up NIRS related issues on bugzilla. Related to the plottting: we (i.e. Roemer, Arjen and me) recently made a lot of progress for handling iEEG data. We also improved handling for iEEG layouts, which are patient specific and sometimes include ECoG at the top and sEEG at the bottom of the brain. iEEG is mostly handled as EEG in FT, but with regards to (a.o. bipolar) "channels" versus "electrodes" it resembles NIRS in some aspects. Just to keep in mind...