trigger

Forum for software developers to discuss BCI2000 software development
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ashwini
Posts: 12
Joined: 04 Mar 2013, 05:17

trigger

Post by ashwini » 11 Mar 2013, 06:06

hi everyone,
We are interested in performing a P300 session by using visual stimulus or sound stimulus. (not using P3 speller matrix). our main concern is to synchronise the stimulation(ex: buzzer, clap sound) with the trigger. Also we would like to know how to give the trigger to the G.tec amplifier(G.USB amp). Please give us your inputs on this matter.

Thanking you,
Ashwini

ashwini
Posts: 12
Joined: 04 Mar 2013, 05:17

Re: trigger

Post by ashwini » 11 Mar 2013, 06:12

Please help...!

mellinger
Posts: 1163
Joined: 12 Feb 2003, 11:06

Re: trigger

Post by mellinger » 11 Mar 2013, 11:14

BCI2000 provides the StimulusPresentation application for such purposes:
http://www.bci2000.org/wiki/index.php/U ... tationTask

You don't need to record triggers through the amplifier, because BCI2000 will record stimulation time in the StimulusTime state. This is a value with millisecond resolution, but it will only be accurate up to the refresh interval of the monitor used (typically around 17ms).

If you think you need higher accuracy, make sure to read this introduction to the P300 response:
http://www.bci2000.org/wiki/index.php/U ... 0_Response
As you can see there, the width of a P300 response is much larger than 17ms, and not much variation occurs on a time scale below 50ms. This implies that there is no need for better temporal accuracy in P300 experiments.

HTH,
Juergen

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