You stated that your trial is 10 seconds; however, there is only 1
second of stimulation. What is going on for the other 9 seconds and
are you saying the fixation will between these 10 second trials?
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Office: (773) 406-2464
=====================
This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED
HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is
intended only for the use of the individual or entity named above. If the
reader of the e-mail is not the intended recipient or the employee or agent
responsible for delivering it to the intended recipient, you are hereby
notified that you are in possession of confidential and privileged
information. Any unauthorized use, disclosure, copying or the taking of any
action in reliance on the contents of this information is strictly
prohibited and may be unlawful. If you have received this e-mail
unintentionally, please immediately notify the sender via telephone at (773)
406-2464 or email.
2011/6/23 Fanny Eugène <[log in to unmask]>:
> Dear SPMers,
>
> I need some advice on timing parameters for an event-related design. Each of my trials lasts 10 seconds, with a 1-second video clip presented 4 s. after the start of the trial. I’m only interested in brain activation during the clip and how it varies across 4 conditions (4 types of video clips). I plan to present a fixation cross of varying durations between trials.
>
> From what I understand, since I plan to contrast activation across conditions and I’m not interested in contrasting each condition with a baseline (null events), the duration of my fixation cross does not need to be very long, but only needs to shift the timing of my events so that they do not always start at the beginning of a TR. Is this right?
>
> With a 3 sec TR, would it be ok for me to use a fixation cross with durations that vary randomly from 500ms to 2500ms in steps of 500ms?
>
> Any advice would be very helpful, thanks!
>
> Fanny
>
|