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Dear Clayton,
<br>
<br>
you are doing the right thing. You could also run ICA on the continuous
data before extracting data epochs and then you would have this
problem.
<br>
<br>
First, it seems normal that you will lose some epochs because most of
them correspond to different conditions than the one you are interested
in.
<br>
<br>
Second if you have a large window for the original epochs (let say 3
seconds from -1 to 2 seconds) and your time-locking events are every 1
second for instance, then over the course of a 3-second epoch you will
have several events (for instance, one at -1s, one at 0s obviously, one
at 1 second and one at 2 seconds). When you re-epoch the data, not only
the events at 0s are considered but also all events at -1s,1s, and 2s.
However, for these non-0 events, your new epoching window (let say
still -1 to 2 seconds) will not allow to extract a full epoch and
EEGLAB will return the "out of boundary" message you mentionned.
<br>
<br>
Hope this helps,
<br>
<br>
Arno
<br>
<br>
<blockquote type="cite">Hello all,
<br>
<br>
I'm having some difficulty in re-epoching a dataset.
<br>
<br>
I'm doing vision research, and want to correct for blink artifacts but
discard trials in which eye movements took place. I'm currently
starting analysis by modifying event codes such that relevant
conditions are identified. I then epoch the data such that all relevant
trials are selected, and run infomax ICA on this 'grand' dataset.
Later, I identify components associated with blinks, and components
associated with eye movements. I remove the components associated with
blinks, but discard epochs associated with eye movements. I then
re-epoch the clean dataset such that each condition is stored in its
own datafile.
<br>
<br>
When I re-epoch, I lose a number of trials, sometimes the majority. For
example, here's the output I receive on one try:
<br>
<br>
[<b class="moz-txt-star"><span class="moz-txt-tag">*</span>code<span
class="moz-txt-tag">*</span></b>]
<br>
>> test = pop_epoch(EEG, {'223'}, [-0.5 1.0]);
<br>
pop_epoch():212 epochs selected
<br>
Epoching...
<br>
Warning: event 7 out of data boundary
<br>
Warning: event 12 out of data boundary
<br>
Warning: event 53 out of data boundary
<br>
Warning: event 66 out of data boundary
<br>
Warning: event 69 out of data boundary
<br>
Warning: event 84 out of data boundary
<br>
Warning: event 87 out of data boundary
<br>
Warning: event 104 out of data boundary
<br>
Warning: event 107 out of data boundary
<br>
Warning: event 124 out of data boundary
<br>
Warning: event 137 out of data boundary
<br>
Warning: event 140 out of data boundary
<br>
Warning: event 147 out of data boundary
<br>
Warning: event 152 out of data boundary
<br>
Warning: event 157 out of data boundary
<br>
Warning: event 162 out of data boundary
<br>
Warning: event 165 out of data boundary
<br>
Warning: event 168 out of data boundary
<br>
Warning: event 193 out of data boundary
<br>
Warning: event 208 out of data boundary
<br>
pop_epoch():192 epochs generated
<br>
pop_epoch(): time limits have been adjusted to [-0.500 1.000] to fit
data points limits
<br>
eeg_checkset: recomputing the ICA activation matrix ...
<br>
pop_epoch(): checking epochs for data discontinuity
<br>
[<b class="moz-txt-star"><span class="moz-txt-tag">*</span>end code<span
class="moz-txt-tag">*</span></b>]
<br>
<br>
I'm not sure what it means that the events are out of the data
boundary, as I'm epoching based on a single event code. I have traced
this error in epoch.m, but the code is reasonably complicated and I
can't quite figure out what's going wrong. Has anyone else had similar
troubles? Or perhaps does anyone have any insight?
<br>
<br>
Thanks very much,
<br>
<br>
Clayton Hickey
<br>
Vrije Universiteit Amsterdam
</blockquote>
<br>
<br>
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