Using emg signal as trigger

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1

hello.

I've just finished to read this tutorial about stimulation delays and I wanted to see the impact of it on my data. So my experiment is a motor task using visual stimulus. The motor task duration is 15s with ~15s of resting state.

I have access to the beginning/end of each task and to the emg.

I am able to load the .eeg file and to perform the analog trigger detection but the main problem here is that my records NIRS and EMG don't start at the same time. so when I export the events and import them in my NIRS data, the timecode don't match.

Can I use the fact that I know that my event related marker ( S1 and S2) appears in the same time in my NIRS data and in my emg data to synchronise the signals ?

signal_emg
signal_emg1533×601 36 KB

and by the way, how could I detect the end of the task ? ( ~ 200ms after S2 )

edit : i've just seen that there is a process for that : Synchronise > transfer events ( from A to B) but it doesn't work :

Error using horzcat
Dimensions of matrices being concatenated are not consistent.

Error in process_evt_transfer>Run (line 155)
t_min = min([sEvents.B{iTrialB}.times]); % first event time in this trial of set B

Error in process_evt_transfer (line 24)
eval(macro_method);

thx for your help :slight_smile:

2

Hello

i’ve just seen that there is a process for that : Synchronise > transfer events ( from A to B) but it doesn’t work

If you get the error you report, it is probably because one of your file in input does not contain the synchronizing event, or because they don't appear the same number of times in the two files.
You could try to start with one single sync event at the beginning of the recordings session (added manually).
Make sure there is not synchronization issue at the end of the recordings (for long sessions, slight clock desynchronization can cause important timing variations)

Have you read the corresponding tutorial?
https://neuroimage.usc.edu/brainstorm/Tutorials/EyetrackSynchro

how could I detect the end of the task ? ( ~ 200ms after S2 )

Detect from what type of information?