[Eeglablist] How to epoch EEG data based on the latency of square waves in a trigger channel

[Kaelasha Tyler]

Hi all,

I am wanting some advice on epoching EEG data based on the latency of
square waves in a trigger channel. How would you do it?

I am using a Compumedics Profusion4 software for EEG recording and
receiving triggers into the data as brief square waves sent as a TTL pulse.
These square waves arrive in a separate trigger channel.
Different conditions are marked by square waves with different voltages.

Because there is no high level information on triggers in the data set, I
cannot just use Tools>extract epochs in EEGlab. Basically I need to add
that information, based on the latency and the voltage of the square waves.

I can easily create a short Matlab routine to pick out the latencies of
these square waves, and create a vector of these latencies. But then how to
get that in to the data set?

Any suggestions?

Thanks in advance!

Kaelasha