Dear Xuelin,
The HRF, or Haemodynamic Response Function, is a fundamental
concept in FMRI. If you do not know about this I suggest that you
read some of the basic texts on FMRI such as:
- Functional MRI: An Introduction to Methods; P Jezzard, PM
Matthews, SM Smith (Eds); Oxford University Press
- Introduction to Functional Magnetic Resonance Imaging:
Principles and Techniques; RB Buxton; Cambridge University Press
- Functional Magnetic Resonance Imaging; SA Huettel, AW Song, G
McCarthy; Sinauer Associates
These should be more accessible than any particular papers.
All the best,
Mark
On 1 Apr 2007, at 21:41, Xuelin Cui wrote:
> hi Andreas:
>
> I read the slides you mentioned, the fMRI intro slides. To be
> honest to you, although it looks good, but I still dont quite get
> the experiment. Is there a paper detailedly discribe the experiment?
>
> Thanks
>
> Xuelin
>
> ****************************************
> Xuelin Cui
> Department of Electrical Engineering
> University of Hawaii-Manoa
> Honolulu HI 96822
>
> Tel: 1-808-349-0983
> Email: [log in to unmask]
> ****************************************
>
> ----- Original Message -----
> From: Andreas Bartsch <[log in to unmask]>
> Date: Saturday, March 31, 2007 10:13 pm
> Subject: [FSL] AW: [FSL] AW: [FSL] how to relate each IC to
> different tasks?
> To: [log in to unmask]
>
>> Hi Xuelin,
>>
>> why don't you start with
>> http://www.fmrib.ox.ac.uk/fslcourse/lectures/intro1/
>> mri_fmri_intro_slides.pdf , see page 49 in particular. Or join one
>> of the next FSL courses. I know - it is a long trip from Hawaii
>> but it may be worth it.
>> Lets say you have a boxcar type of experiment (see page 42 of the
>> pdf), you can model this be a series of "0" and "1" entries. You
>> can simply take this vector and correlate with the t*.txt from
>> melodic's output. Alternatively, you may want to convolve your
>> expected response vector with a hemodynamic response function -
>> e.g. a synthetic like the double-gamma HRF or even an empirical
>> one obtained specifically for your type of stimulus / brain region
>> / experiment.
>> Hope this helps-
>> Andreas
>>
>> ________________________________
>>
>> Von: FSL - FMRIB's Software Library im Auftrag von Xuelin Cui
>> Gesendet: Sa 31.03.2007 00:07
>> An: [log in to unmask]
>> Betreff: Re: [FSL] AW: [FSL] how to relate each IC to different
>> tasks?
>>
>>
>>
>> hi Andreas:
>>
>> Thanks for your reply.
>>
>> But I dont totally understand what you said. Could you please
>> explain a little bit more on that: "However, you can simply
>> correlate your design (boxcar or, for event-related studies
>> namely, your stimulus-/response-ons convolved with some type of
>> HRF)" What is a HRF? Do you have an example, or a relevant paper?
>>
>> Thanks
>>
>> Xuelin
>>
>> ****************************************
>> Xuelin Cui
>> Department of Electrical Engineering
>> University of Hawaii-Manoa
>> Honolulu HI 96822
>>
>> Tel: 1-808-349-0983
>> Email: [log in to unmask]
>> ****************************************
>>
>> ----- Original Message -----
>> From: Andreas Bartsch <[log in to unmask]>
>> Date: Tuesday, March 20, 2007 3:26 pm
>> Subject: [FSL] AW: [FSL] how to relate each IC to different tasks?
>> To: [log in to unmask]
>>
>>> Hi,
>>> Strictly speaking: you can't (- at least not by just running a
>>> single experiment and analysing it;)
>>> However, you can simply correlate your design (boxcar or, for
>>> event-related studies namely, your stimulus-/response-ons
>>> convolved with some type of HRF) with the time-course (in SD
>>> units) of the respective tXX.txt file. Or even easier, if you have
>>> no spatial hypothesis whatsoever, select those Ics whose FFT are
>>> peaking at the appropriate frequency and then look at the time-
>>> courses, if they are synchronous to your paradigm.
>>> Hope that helps-
>>> Andreas
>>>
>>> -----Ursprüngliche Nachricht-----
>>> Von: FSL - FMRIB's Software Library [mailto:[log in to unmask]] Im
>>> Auftrag von Xuelin Cui
>>> Gesendet: Dienstag, 20. März 2007 00:55
>>> An: [log in to unmask]
>>> Betreff: [FSL] how to relate each IC to different tasks?
>>>
>>> hi folks:
>>>
>>> I here have a question. I am doing the ICA analysis on fMRI data.
>>> But I am confused on how to relate rach IC extracted from the fMRI
>>> data to different tasks. Put in this way: if I see an IC, how can
>>> I tell the IC is caused by what kind of reason?
>>>
>>> Anyone could give any suggestions? I really appreciate your
>> thoughts.>
>>> Thanks
>>>
>>> Xuelin
>>>
>>> ****************************************
>>> Xuelin Cui
>>> Department of Electrical Engineering
>>> University of Hawaii-Manoa
>>> Honolulu HI 96822
>>>
>>> Tel: 1-808-349-0983
>>> Email: [log in to unmask]
>>> ****************************************
>>>
>>
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