[FieldTrip] Difficulty detecting TTL pulses with ft_read_event

Jonathon James Parker parkerjo at stanford.edu
Fri Oct 25 19:56:22 CEST 2019

Hi FieldTrippers:

I am a LFP/Brain stimulation researcher new to FieldTrip @Stanford.

I have run across some difficulty using the ft_read_event  to detect TTL pulses and triggering my data into discrete epochs

I have 14 channels of LFP data and 1 channel of trigger data recording using a gTec USBAmp-Research.  I have successfully read in the data, filtered-it, re-referenced channels of interest, and appended the un-filitered trigger channel (‘TRAIN’).

The TTL pulses are on (value ~1) while stimulation is on. I would like to trigger based on the upgoing flank.

Each time I run ft_read_event, I have passed it the isolated trigger channel data, but I receive this error:
[cid:image002.png at 01D58B22.76EEAD40]

Does anyone have sample scripts they could share with use of ft_read_event to detect TTL pulses?

See my full code below:

[cid:image004.png at 01D58B22.D7510DE0]

Thank you!


Jonathon J. Parker MD PhD
Stanford University
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