Timing issues

[Rachel Mitchell]

Hi everyone
Although my queries below relate to my wish to use Eprimne for some fMRI
studies, I think the non-imagers amonst you can probably help me too

Basically, in our scanning set up, we have a trigger system connected to the
scanner which tells your PC via a modified mouse when the scanner has
started collecting data, so your stimulation program starts at exactly the
same time
So, I set Eprime to begin on receiving a left mouse click (albeit a pretend
one from the scanner)

1) Now as I understand it the scanner will send a pulse signal to the
modified mouse everytime it collects 1 brain volume.
What I am concerned about is that when a subject presses a response button
on the subject response unit (made by Lumitouch) won't Eprime get confused
between these 2 signals or will it recognise the response unit as a
completely separate input unit from the scanner trigger/mouse

2) In some studies, I would want Eprime to start displaying a new stimulus
every time it gets a trigger signal from the scanner. How do I achieve this?
I don't want to register the pretend mouse click as a subject response, I
want to use the pretend mouse click to begin the presentation of each
stimulus

3) I was reading the chapter in the user guide on timing issues. It talks
about designing a callibration experiment to enable you to calculate a
scaling factor to adjust Eprime in cases where timing is absolutely
critical. I'm quite unclear on this, espec what sort of expt to devise

4) It also talks about sending a signal from Eprime to external monitoring
equipment to timestamp a synchronisation signal, but in an fMRI situation I
can send a signal from the scanner to Eprime, but am not sure I can send a
signal from Eprime to the scanner?

I hope someone can point me in the right direction, so I'll thank you in
advance for any help you can give

Regards
rachel

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Dr Rachel L. C. Mitchell
Lecturer in Cognitive Psychology, University of Reading
Honorary Research Fellow, Institute of Psychiatry

Correspondence Address:
School of Psychology
Whiteknights Road
University of Reading
Reading
Berkshire
RG6 6AL

Tel: +44 (0)118 378 8523
Direct Dial: +44 (0)118 378 7530
Fax: +44 (0)118 378 6715
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