Dear Rik,
I note that your HBM abstract describes F-contrasts with the FIR method and
that the SPM99 manual also suggests F-contrasts are need for meaningful
inference (p. 39). However, your paper on repetition priming in the
Scandinavian Journal of Psychology reports t-contrasts performed on
parameter estimates from several bins. This suggests that a second-level
analysis might be conducted with t-contrast images derived using the FIR
method. Could you clarify whether this is the case?
Regards,
Greig
> From: Rik Henson <[log in to unmask]>
> Reply-To: Rik Henson <[log in to unmask]>
> Date: Thu, 6 Sep 2001 18:22:50 +0100
> To: [log in to unmask]
> Subject: Re: FIR basis?
>
>
> Attached is an extended version of spm_get_bf.m that
> includes an FIR basis set for event-related analyses (which
> prompts for binsize, in seconds, and number of bins - see
> SPM manual for more details) and that should work fine
> with the released version of SPM99.
>
> For the pros and cons of an FIR model to make inferences,
> see Henson et al. (2001), HBM01 abstract, Neuroimage, 13, 149,
> though note erroneous labelling of figures in published version;
> correct version available from:
>
> http://www.fil.ion.ucl.ac.uk/~rhenson/refs.html
>
> and for the use of an FIR model to plot data as a function of
> peristimulus time, see recent posting by Russ Poldrack:
>
> http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0108&L=spm&P=R6690
>
> http://www.nmr.mgh.harvard.edu/~poldrack/spm/pst_avg.html
>
> Best wishes
> Rik
>
>
> Souheil Inati wrote:
>
>> Reading through the fine SPM manual by Dick Veltman and Chloe Hutton I
>> came across the following in the section on event related fMRI model
>> specification"
>>
>> basis functions (Finite Impulse Response): uses a set of 'mini-boxcars'
>> to model peri-stimulus time.
>>
>> In my version of spm99, this option is not available. If I search
>> through the code of spm_get_bf, I don't see this. It also doesn't seem
>> to be in the updates.
>>
>> This is a great way to do the analysis. I've been doing it by hand and
>> it's a pain.
>>
>> Any info would be greatly appreciated.
>>
>> Thanks,
>> Souheil
>
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> ---------------------------8-{)}-------------------------
>
> DR R HENSON
> Wellcome Department of Cognitive Neurology
> & Institute of Cognitive Neuroscience
> University College London
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--
Dr Greig de Zubicaray
Centre for Magnetic Resonance
The University of Queensland
Brisbane, QLD 4072
AUSTRALIA
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