Determining cumulative time for stimuli

[I][edited from support email][/I]
We are busy using DirectRT and have a lot of fun with it. Have I already mentioned, that I enjoy very much the way the User’s Guide is written? Well, we now want to use it for an experiment that includes the use of a MRf. Our problem is to know, at which moment exactly DirectRT presents a stimulus. We need that to be able to tell, at which stimulus the patient’s brain presents which activation. I know that the output file tells us about the time of presentation of the stimulus and the time the patient needed to respond, but it would be quite a lot of work to calculate the moment of each presentation. Is there a possibility of starting some kind of “counter” at the moment when all the introduction has been presentated and the stimuli start? That would help a lot.

Yes, there is a column in the log version of the data file called "started@" which will tell you the number of milliseconds passed since the beginning of the session. You could also send out a TTL signal to your other software/hardware at any point during each trial--that is also a common way of synching stimulus presentation info with psychophys data.

Hope that helps,
Blair

[I][edited from support email cont'd][/I]

The company NordicNeuroLab developed a so called "SyncBox" that sends triggers from a fMR to the computer that is running the stimulus programme, in our case DirectRT. Does DirectRT catch and register those triggers and do I find these also in the log-file? Or do I have to make any configurations first?

Yes, you could have DirectRT intercept those signals and save those data to the same file where the stim presentation data are located. Take a look at the section in the manual on [URL="http://www.empirisoft.com/directrt/help/directrt_samples_of13_ttl_signals.htm"]receiving TTL signals[/URL] for details. Let me know if you have any trouble with it.