[FieldTrip] Adding Manual Markers

[Stephen Whitmarsh]

Merhaba Mustafa,

Welcome to FieldTrip!
Just to be clear - I assume you segmented your continuous data into trials
by passing your marker timing as a cfg.trl in ft_preprocessing, right?
When you did, the temporal information about the markers became irrelevant,
because the trials are then expressed *not *in samples from the onset of
the continuous data anymore, but instead as time relative to the markers.
I.e. each trial now starts at t=0s (-offset), rather and, say [13, 104,
206, ...] samples (i.e. your initial trl). See the resultant data.time
field.
Secondly, ft_databrowser does not take cfg.trl as the location of markers,
rather it does so in cfg.artfctdef.xxx.artifact (yes, a bit strange, partly
historical, and because databrowser is typically used to manually scan for
artifacts).

So, in your case, you could either:

Use ft_databrowser to plot the original, unsegmented, continuous, data, and
pass your trialinfo (as a Nx2 matrix, with only start and end sample) to
cfg.artfctdef.xxx.artifact. Replace xxx with whatever your want, e.g.
"trialnumber"
Use ft_databrowser to plot the segmented data, as trials, with new
time-axis, without the markers.

Note that ft_databrowser will try to fit your cfg.artfctdef.xxx.artifact to
your segmented trial data as well, by doing some intelligent checking of
your past cfg (which is tracked in your segmented data structure and
beyond), and treating your data as continuous data. That might work, or it
might not, but now you know why!

Happy fieldtripping,
Stephen



Op di 24 nov. 2020 om 02:29 schreef MUSTAFA YAVUZ <m.yavuz.18 at ogr.iu.edu.tr
>:

> Hi all,
>
> I've been trying to adjust my EEG data (segmented and .mat file) to be
> analyzed by FT. I already have separate trials and have temporal
> information about the event markers' time courses. I constructed a Nx3 trl
> structure and passed it as cfg.trl while calling ft_preprocessing. Whilst
> the function worked and I can see the cfg.trl field in the output
> structure, when I call ft_databrowser, the event markers are not displayed
> on trials. Do you have any idea/solution for this situation?
>
> Thank you in advance,
> Mustafa
>
> --
> *Mustafa Yavuz *
>
> Ph.D. Candidate in Neuroscience
>
> Department of Neuroscience
> İstanbul University
>
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> https://doi.org/10.1371/journal.pcbi.1002202
>
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