Thanks!
On May 5, 2007, at 1:30 AM, Steve Smith wrote:
> Hi - how the FIRs look depends on the interaction between individual
> FIR impulse duration, TR and input stimulus timings (onset and
> duration). The window length is probably enough - what you're seeing
> is most likely just a combination of those timing factors.
>
> Cheers.
>
>
> On 5 May 2007, at 09:22, Junghee Lee wrote:
>
>> HI
>>
>> Thanks a lot for reply. I do have another related question. When I
>> tried a window of 14 seconds, the hemodynamic functions of 4 EVs look
>> physiologically plausible. However, when I tried a window of 12
>> seconds, the hemodynamic functions of 3 EVs did not look right (the
>> one EV looked a little better than others). I wasn't sure whether
>> the FIR impulse is sensitive to the window length. Is this because I
>> didn't have enough time window to cover the hemodynamic rise and fall
>> time?
>>
>> Thanks,
>> Junghee
>>
>>
>> On May 5, 2007, at 12:10 AM, Steve Smith wrote:
>>
>>> The window length is divided by the number of FIR impulses that you
>>> ask for so that each impulse has duration length/number seconds.
>>> A common approach is to organise that so that the length covers the
>>> normal haemodynamic rise and fall time (eg 15 seconds) and set the
>>> number so that each is one TR in duration.
>>> Cheers.
>>>
>>>
>>> On 4 May 2007, at 23:16, Junghee Lee wrote:
>>>
>>>> Hello Everyone,
>>>> I have a question of using FIR basis function. We used a fast
>>>> event-related design (TR=2) and there are 4 EVs. I would like to
>>>> compare a window of 12 seconds and a window of 14 seconds.
>>>>
>>>> I'm not sure whether I understand what "number" means exactly. Is
>>>> this number of FIR basis functions? If so, is there any optimal
>>>> number of functions I should use?
>>>>
>>>> Thanks a lot!
>>>> Junghee
>>>
>>>
>>> ---------------------------------------------------------------------
>>> ------
>>> 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
>>> ---------------------------------------------------------------------
>>> ------
>>>
>>>
>> ------------------------------------
>> Junghee Lee
>> Post-doctoral fellow
>> Semel Institute of Neuroscience and Hunan Behavior, UCLA
>>
>> Phone: 310-478-3711 ext.42986
>> email:[log in to unmask]
>> Mail: UCLA/VA Greater Los Angeles Healthcare System
>> 11301 Wilshire Blvd.
>> MIRECC, Bldg. 210 (MC 210A)
>> Los Angeles, CA 90073
>> Web:http://greenlab.npih.ucla.edu or
>> http://www.psy.vanderbilt.edu/students/leej11
>
>
> -----------------------------------------------------------------------
> ----
> 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
> -----------------------------------------------------------------------
> ----
>
>
------------------------------------
Junghee Lee
Post-doctoral fellow
Semel Institute of Neuroscience and Hunan Behavior, UCLA
Phone: 310-478-3711 ext.42986
email:[log in to unmask]
Mail: UCLA/VA Greater Los Angeles Healthcare System
11301 Wilshire Blvd.
MIRECC, Bldg. 210 (MC 210A)
Los Angeles, CA 90073
Web:http://greenlab.npih.ucla.edu or
http://www.psy.vanderbilt.edu/students/leej11
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