Hi - yes, you can allow flexibility in your HRF in a number of ways
through the different basis function HRF Convolution options. You
could leave it very unconstrained using the "FIR" option, but it is
better to use the "Optimal basis functions" which give an optimal
balance between restricting the HRF to a range of sensible shapes, and
yet being flexible.
Cheers, Steve.
On 25 Apr 2008, at 19:00, Michael Keaser wrote:
> Steve,
>
> I've read the various model setup settings described in the FEAT
> manual.
> I've used AFNI in the past, and FSL is a little more unfamiliar. I
> know in
> AFNI you can use minlag and maxlag in your GLM model where you do
> not pre-
> determine the HRF model shape. You simply specify the time lag(s) you
> expect the your response to a stimulus may have. I was wondering if
> you can
> do the same thing with FSL.
>
>
> On Thu, 17 Apr 2008 08:37:36 +0100, Steve Smith <[log in to unmask]>
> wrote:
>
>> HI - please see the various model setup setting described in the FEAT
>> manual.
>> Cheers, Steve.
>>
>>
>> On 16 Apr 2008, at 18:26, Michael wrote:
>>> Hello,
>>>
>>> How do you incorporate a time delay of the stimulus onset for the
>>> model in
>>> FEAT?
>>>
>>> For example, I have stimulus on period of 7 TR's (TR = 2 seconds)
>>> and an
>>> off time of 7 TR's.
>>>
>>> Thus,
>>>
>>> 1's = on, 0's = off-time
>>>
>>> 1 1 1 1 1 1 1 0 0 0 0 0 0 0
>>>
>>> I'm not using a pre-determined model shape like a gamma function,
>>> etc.
>>>
>>> How do you put a lag of, say, 3 TR's (or six seconds) in your full
>>> model
>>> setup.
>>>
>>> Thanks,
>>>
>>> Michael
>>>
>>
>>
>> ---------------------------------------------------------------------------
>> Stephen M. Smith, Professor of Biomedical Engineering
>> Associate Director, Oxford University FMRIB Centre
>>
>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>> +44 (0) 1865 222726 (fax 222717)
>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>> ---------------------------------------------------------------------------
>> =
>> =
>> =
>> =
>> =====================================================================
>
---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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