The contrast is formed from a vector. That same vector is used to
create the T-maps.
I believe I have the equations in my presentation entitled: Seminar:
The GLM (General Linear Model)-- first and second-level models
[summary]
Athinoula A. Martinos Center for Biomedical Imaging, MGH, Boston, MA
It can be found on my website under Science --> Presentations
(http://www.martinos.org/~mclaren)
These are standard equations for contrast images, T-map images, and
F-map images.
On 8/24/12, ·ëè´ <[log in to unmask]> wrote:
> Thank you for your response.
> But, at individual level, we also have a T map. What I wonder is how does
> SPM calculate this individual-level T map...
>
> Best,
> Lu FENG
> _____________________
>
> Medical Image Processing Group
> Institute of Automation, Chinese Academy of Sciences
>
>
> -----Original Message-----
> From: Jidan Zhong [mailto:[log in to unmask]]
> Sent: 2012Äê8ÔÂ24ÈÕ 8:53
> To: ·ëè´
> Subject: Re: [SPM] How does SPM calculate the T map?
>
> Hi
>
> For each subject, each voxel, you get a "con". SPm T map is based on
> the second level (group analysis), which means you need to have
> multiple subjects' "con" to form a vector. The SPm can give a T map.
>
> On 8/23/12, ·ëè´ <[log in to unmask]> wrote:
>> Dear experts,
>>
>>
>>
>> Maybe it¡¯s a naive question¡ But I have to ask¡
>>
>>
>>
>> We know that each voxel has one beta value for one condtion (a column in
>> the
>> Design Matrix) after model estimation.
>>
>> If we have two condition, then we get beta1 and beta2 in one voxel.
>>
>> Next, we can get con = beta1 ¨C beta2 in one voxel.
>>
>> But, for one voxel, con is a number, not a vector, how can SPM do a t
>> test
>> in one voxel?
>>
>>
>>
>> Best,
>>
>> Lu FENG
>>
>> _____________________
>>
>>
>>
>> Medical Image Processing Group
>>
>> Institute of Automation, Chinese Academy of Sciences
>>
>>
>>
>>
>> --
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>
>
> --
> Regards,
>
> Jidan
>
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Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital
and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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