Hello,
Thanks for the cooperation. Yes, I know that paper, and also the parent
paper:
An empirical investigation into the number of subjects required for an
event-related fMRI study.
Kevin Murphy and Hugh Garavan, NeuroImage
Volume 22, Issue 2, June 2004, Pages 879-885
As I use FSL, I'm not sure if the same conclusions can be applied. Even
so, I use always more than 25 events.
In my studies, I ask to the participants to make assessments, which is a
much more demanding activity than finger tapping. It can be that 25 events
are too much from the human perspective. Maybe from the twentieth event
the participant loosed concentration or just isn’t cooperating anymore. In
these cases, increasing the number of events is useless or it can be
worst, as the extra events just add noise (because the participant is
using different brain structures).
So, I’m looking for a method to reduce the length of the studies to an
optimal minimum. Also, I’m looking if, between the required signal and the
exhaustion of the participants, there is a window to perform the study.
I’ve serious doubts about the results of a study where exhaustion arrives
first than enough signal.
Kind regards,
Jose Paulo Santos
On Fri, 30 May 2008 09:30:29 +0100, Colm G. Connolly
<[log in to unmask]> wrote:
>On 28 May 2008, at 19:10, Jose Paulo Santos wrote:
>
>> I'm trying to establish some kind of method to achieve to the optimal
>> length in event-related paradigms.
>
>
>If you haven't seen this paper it might be of use to you.
>
>Deriving the optimal number of events for an event-related fMRI study
>based on the spatial extent of activation
>Kevin Murphy and Hugh Garavan, NeuroImage
>Volume 27, Issue 4, 1 October 2005, Pages 771-777
>
>Regards,
>--
>Dr Colm G. Connolly
>School of Psychology and Institute of Neuroscience
>The Lloyd Building
>University of Dublin
>Trinity College, Dublin 2, Éire
>Fax: +353-1-671-3183
>
>Please note that electronic mail to, from or within the Trinity
>College Dublin, may be the
>subject of a request under the Freedom of Information Act.
>========================================================================
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