e-prime triggered by MR scanner

[Eric Claus]

Cristoph,

I am not sure how you are sending the pulses, but if you can verify
that you are sending a TTL through a parallel cable this may help.

1.  Make sure your port is in Standard mode (this can be changed in
BIOS when you restart).  On Gateway computers, the setting is Output
only.  Do not use EPP, ECP, or Bi-Directional
2.  To read input, the TTL must come in on any of the following pins:
15, 13, 12, 11, 10 (11 is inverted).  In e prime, you will have to
identify which bit to read, so you will need a bit to pin map.
<http://www.doc.ic.ac.uk/~ih/doc/par> has a bit to pin map that we
used.
3.  You also will need a ground wire.  The parallel cable we used had
a separate ground, but within the cable itself, pins 18-25 are ground
wires.
4.  After you are sure you can receive a TTL through one of the pins
mentioned above (10, 11, 12, 13, 15), then you can proceed to the
programming.
5.  In the Structure window of E prime, click on the top of your
experiment structure (This should say Experiment (experiment name).
Go to the Devices tab, Click Add, and click on Port.  Next, configure
the port by double clicking on the Port icon.  Make sure the Address
is set to &H379 (although you should check this in your computer
manuals to make sure this is the correct port address), Size 8, Invert
No, Mask -1.
6.  After you have added and configured your port, you should be able
to trigger a stimulus without too much problem.  Something I have used
to test this is a simple "experiment" that shows a blank screen and a
fixation cross.  When the TTL pulse is received, the fixation cross
appears until the subject responds, leaving a blank screen again.
Here is how it is set up.  I have the TrialProc with a Target module
and a Fixation module (both TextDisplay's).  Under the Properties of
the Target, click on Duration/Input tab, and under Input Devices, Add
a Port device.  For the Allowable Input, put 'any' or one of the bits
that correspond to the pin your signal is being sent through (use map
from #2).  This will tell e prime to read the signal through any bit
or the specific bit you choose.  Time Limit should be infinite, and
Input Action should be set to Terminate.  Also, under the Duration
setting, you should set this to a large number, as a small number (ie
1000) would cause the blank screen to terminate before the TTL pulse
is received.

As long as you have a something on the TrialProc before the actual
stimulus, you should be able to display stimuli each time a TTL pulse
is received.

Hope this helps.  The E prime email support was very helpful with this
problem and usually responded within the day, if you are still having
trouble.

Eric
-------------------
> Dear e-prime users
> Is there any one who has experience with MR-triggered (via the
paralleport)
> stimulus-presentation. We would like to have each (!) stimulus
presentation
> triggered by our Siemens MR Scanner. Since the scanner usually sends
a TTL
> impulse for every slice, one should be able to count each pulse at
the port
> in the background until the first slice is measured again and then
present
> the next stimulus. If there is anyone who could help us, we would be
very
> grateful.
> Thanks a lot
> Sincerely
> Christoph L
>
> ------------------------------------------
> University Hospital of Clinical Psychiatry
> Department of Psychiatric Neurophysiology
> Neuroimaging Group
> Bolligenstrasse 111
> CH-3000 Bern 60
> Switzerland
>
> Phone : ++41 31 930 93 83
> E-Mail: lehmann at puk.unibe.ch
>
>
>

Eric Claus, B.S.
Department of Psychology
School of Science
Indiana University-Purdue University at Indianapolis