Continuous Response Collection (fMRI TR)

Quant_Lab

Hi all,

I have been trying to find the best way to continuously collect a response while an experiment is running. The goal–while running an fMRI experiment, the scanner sends a "5" keypress to the program before each TR, and I want to log this response for sanity checks later on. I have looked into relevant discussions on how to accomplish this to no avail. Right now, I seem to have 2 options:

1) Make sure that all trial lengths are equivalent and use padding (http://forum.cogsci.nl/discussion/298), or
2) Set up some sort of custom co-routine (http://osdoc.cogsci.nl/3.1/manual/structure/coroutines/)

The problems with these methods are that:

1) I cannot have equal-length trials for event-related designs in fMRI, and
2) Co-routines make use of generator functions, which still rely on a single thread (i.e. not truly parallel) and I am not sure if they will work in my situation.

So, am I wrong or is it not possible to collect the responses that I am interested in using OpenSesame? Any advice would be greatly appreciated!

eduard

Hi,

If you intend to record each trigger than the scanner sends, I wouldn't know how to implement this without affecting your experiment. But, if you just need a couple of triggers for sanity checks. You can just sample key presses throughout your experiment at some times.

kb = keyboard(keylist = ['5'],timeout = 0)
var.key, var.t = kb.get_key()

Does this help?
Eduard

ejs

I've made a plugin for pausing paradigma until the MRI sends the TR pulse. Not sure if it will help, as the plugin works via serial port (USB-Serial actually) to keep Nordic Actia software running.
Surelly, there is some constant delay (TR -> conversion to serial -> acquisition of TR in the software - > presentation of the frame), but this can be managed adding extra slice or two.

Quant_Lab

eduard–thank you for the comment. I think this would be my best option.

ejs–I am not interested in syncing the experiment with the TR, only collecting the time at which each TR is sent. That said, thanks for the comment and I am sure there are others that will find it useful!