[Eeglablist] Scroll Plot Marked Trial / Channel Identification

[Tarik S Bel-Bahar]

Hi Frank,

One way to do this (without changing the color of the channel labels on the
y-axis)
is to examine the "indelec" output from the channel rejection function. See
help for that function below.
Turning them red on the y-axis would invovle taking the indelec output and
changing the color
of those specific electrode
Another option is to show fewer channels at a time.
As long as you've filtered or removed baseline on all channels,
you should be able to view sub-group of channels with ease, easily
detecting which ones have been marked.


the following lines run channel artifact detection, save the output
variables, and spits out to the screen
the numbers of the channels that were detected. I have set it so it creates
a new variable containing
the EEG with removed channels. The second line just outputs one of the
output variables that contains
the numbers of the detected channels.

[OUTEEG, indelec] = pop_rejchan(EEG, 'elec',[1:EEG.nbchan]
,'threshold',3,'norm','on','measure','kurt');

indelec




>> help pop_rejchan
  pop_rejchan() - reject artifacts channels in an EEG dataset using joint
                   probability of the recorded electrode.

  Usage:
    >> pop_rejchan( INEEG ) % pop-up interative window mode
    >> [OUTEEG, locthresh, globthresh, nrej] = ...
  = pop_rejchan( INEEG, 'key', 'val');

  Inputs:
    INEEG      - input dataset

  Optional inputs:
    'elec'     - [n1 n2 ...] electrode number(s) to take into
                 consideration for rejection
    'threshold' - [max] absolute thresold or activity probability
                  limit(s) (in std. dev.) if norm is 'on'.
    'measure'  - ['prob'|'kurt'] compute probability 'prob' or kurtosis
'kurt'
                 for each channel. Default is 'kurt'.
    'norm'     - ['on'|'off'] normalize measure above (using trimmed
                 normalization as described in the function jointprob()
                 and rejkurt(). Default is 'off'.
    'precomp'  - [float array] use this array instead of computing the
'prob'
                 or 'kurt' measures.

  Outputs:
    OUTEEG    - output dataset with updated joint probability array
    indelec   - indices of rejected electrodes
    measure   - measure value for each electrode







On Wed, Nov 28, 2012 at 10:41 AM, Frank Preston <ffpresto at uwaterloo.ca>wrote:

>  Hi,****
>
> ** **
>
> If Scroll Plot is opened after trials have been marked by EEGLab, the
> channel which caused the trial to be marked is highlighted in red. We would
> like to know which channel is marked and it is often very difficult to tell
> because the plotted signal is outside of range by quite a bit. Is there an
> easy way to tell this, perhaps by highlighting the channel on the y-axis?*
> ***
>
> ** **
>
> We are viewing results from a BioSemi Active 2 system. We record 72
> electrodes, 66 of which are on the cap.****
>
> ** **
>
> Thank you,****
>
>   .. Frank****
>
> ** **
>
> ** **
>
> --
> *Frank Preston*
> Psychophysiology Lab Technician          University of Waterloo
> PAS 2270, Psychology Department        200 University Ave. W.
> Phone: 519-888-4567 x 38976               Waterloo, Ontario, N2L 3G1****
>
> ** **
>
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