Thanks John.
So the problem may more be stringent if we stay in the population
template space.
Deformation fields locally create dilatation or compression of voxels.
This directly impacts the corresponding grey levels which represent
tissues composition in structural images or de-oxyhemoglobin
concentration in case of functional images.
I do not really understand why modulation makes sense only for the
former case.
Best Regards
M
> ---------- Forwarded message ----------
> From: John Ashburner<[log in to unmask]>
> Date: Tue, 20 Dec 2011 12:44:54 +0000
> Subject: Re: [SPM] modulation for functional images
> To: [log in to unmask]
>
> I don't think "modulation" makes so much sense for spatially
> normalising fMRI. If you use the "normalise to MNI space" option
> without "modulation", there is a correction included so that the
> smoothing accounts for the volumetric changes.
>
> Best regards,
> -John
>
> On 20 December 2011 10:29, Michel Dojat<[log in to unmask]> wrote:
>> Dear All,
>>
>> When applying deformation field calculated using DARTEL pipeline to
>> functional MRI, is it needed to modulate in order to compensate, similarly
>> to VBM applications, for local modification of the images ?
>>
>> thank for your reply
>>
>> M
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