Dear Woo Suk Tae,
F contrasts look for two-sided effects ie. they
can detect positive or negative effects.
When you did the t-test did you look for just a positive effect (ie
+1 contrast vector) ?
If so, then it may be that what you have found is a deactivation.
Check this using a `-1' t-contrast.
Best,
Will.
Woo Suk, Tae wrote:
> Dear SPMers.
> Recently, I got the strange results in auditory fMRI study abou monotopy mappng.
> The results of volunteers seems to good in F-contrasts,
> but in T-contrast, the results seems to be not adequate.
> Now, I am confused whether I report it with F-contrast or not until the results will be good with T-contrast.
> Do you have any suggestions?
>
>
> -----------------------------------------------------------
> Woo Suk, Tae
> Senior Researcher
> Neuroimaging Laboratory. Neurology,
> Samsung Medical Center, Seoul, Korea
>
> Tel: 82-2-3410-2738
> Fax: 82-2-3410-2759
> email: [log in to unmask]
> -------------------------------------------------------------
>
--
William D. Penny
Wellcome Department of Imaging Neuroscience
University College London
12 Queen Square
London WC1N 3BG
Tel: 020 7833 7475
FAX: 020 7813 1420
Email: [log in to unmask]
URL: http://www.fil.ion.ucl.ac.uk/~wpenny/
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