Dear Li Bei,

Ideally, for a DCM analysis, you should have at
least two factors.

One would be a 'driving' factor - factor A, typically
a series of events - though these could be blocked.

The other would be a 'modulatory' factor - factor B, typically
blocked.

DCM is then primarily used to attribute changes in
effective connectivity to factor B.

You should have enough variables in your
design to set up a DCM.

You could specify D = ---AAABBB---AAABBB, ie
A or B. This would be a driving input.

Your modulatory input would then be eg. B.

Best,

Will.

Li Bei wrote:

> Dear Penny:
>     Sorry distrubing you.
>     I'm a begginer of SPM and I have some
> question,could you help me?
>     Is it necessary to have control blocks in DCM
> experiment? if yes, why there is no
>
> vector to speicfy the control block scans in table1?
>       In my lab,we proposed a exp. to observe the
> reponse of brain to different Chinese
>
> words,should we design exp. like
> this?:CCCAAABBBCCCAAABBBCCCAAABBB where C denotes
> Control
>
> block,A denotes condition1,B denotes condition2.
>
> if this exp. is right,how to write instrutions in
> table1?
>
> table1:
> steps in "fMRI" of SPM2
> 11. Number of conditions [3 or ??] // we want to
> observe the over all reponse(A+B),A and B
>                       //respectively
> 12. Name for condition 1 []
> 13. vector of onsets - Photic []
> 13. duration[s] (events=0) []
> 14. Parametric modulation []
> 15. Name for condition 2 []
> 16. vector of onsets - Motion []
> 17. duration[s] (events=0) []
> 18. Parametric modulation []
> 19. Name for condition 3 []
> 20. vector of onsets - Attention []
> 21. duration[s] (events=0) []
> 22. Parametric modulation [None]
>
> 4 seconds long for each character(A,B or C),2 second
> for each scan,that means,there are 2
>
> scans for each character(A,B or C)
>
> Actually, i don't understand DCM well. in you
> instruction publish on you personal website,
> you writed this:
> 11. Number of conditions [3]
> 12. Name for condition 1 [Photic]
> 13. vector of onsets - Photic [phot]
> 13. duration[s] (events=0) [10]
> 14. Parametric modulation [None]
> 15. Name for condition 2 [Motion]
> 16. vector of onsets - Motion [mot]
> 17. duration[s] (events=0) [10]
> 18. Parametric modulation [None]
> 19. Name for condition 3 [Attention]
> 20. vector of onsets - Attention [att]
> 21. duration[s] (events=0) [10]
> 22. Parametric modulation [None]
>
>  Does Photic there mean combination effects of Motion
> and Attention??
>
> and does structure below mean pass over all
> stimulaion(Motion + Attention) to V2,
> and Motion,Attention have their own effect on
> bottom-up connection from V1 to V5 and top-down
> connections from PFC to PPC and from PFC to PPC
> respectivlly  ?????
> 10. Just connect Photic to V2
> 11. Connect Motion to modulate the bottom-up
> connection from V1 to V5
> 12. Connect Attention to modulate the top-down
> connections from PFC to PPC and from PFC to PPC.
>
>
>
> My English is poor,sorry,really sorry.
>
> Looking forward your reply
>
>
> Thanks
>
>
> BeiLi
>
>
>  --- Will Penny <[log in to unmask]> 5DU}ND#:
>
>>Dear Li Bei,
>>
>>You can follow the link on my web page:
>>
>>
>
> http://www.fil.ion.ucl.ac.uk/~wpenny/publications/integration.pdf
>
>>Happy new year !
>>
>>Will
>>
>>Li Bei wrote:
>>
>>
>>>Dear Dr. Penny:
>>>
>>>   Sorry disturbing you!
>>>   I'm a student of Dalian University of
>>>Technology(DLUT,in China) ,i'm working on data
>>>analysis of fMRI.I found that your paper
>>
>>"Modelling
>>
>>>functional integration: a comparison of structural
>>>equation and dynamic causal models "is published
>>
>>on
>>
>>>NeuroImage Volume: 23, Supplement 1, 2004,but the
>>>e-copy of is not avaliable,i'm eager to see your
>>>paper,could you send me one if my request is not
>>>illegal?
>>>
>>>
>>>   Thank you very much.
>>>
>>>
>>>BeiLi
>>>Lab. of Neuroinformatics
>>>DLUT ,China
>>>
>>>
>>
> _________________________________________________________
>
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>>>
>>
> http://cn.rd.yahoo.com/mail_cn/tag/1g/*http://cn.mail.yahoo.com/
>
>>>
>>--
>>William D. Penny
>>Wellcome Department of Imaging Neuroscience
>>University College London
>>12 Queen Square
>>London WC1N 3BG
>>
>>Tel: 020 7833 7475
>>FAX: 020 7813 1420
>>Email: [log in to unmask]
>>URL: http://www.fil.ion.ucl.ac.uk/~wpenny/
>>
>>
>
>
> _________________________________________________________
> Do You Yahoo!?
> W"2aJ@=gR;AwF7VJ5DQE;"Cb7Q5gSJ
> http://cn.rd.yahoo.com/mail_cn/tag/1g/*http://cn.mail.yahoo.com/
>
>

--
William D. Penny
Wellcome Department of Imaging Neuroscience
University College London
12 Queen Square
London WC1N 3BG

Tel: 020 7833 7475
FAX: 020 7813 1420
Email: [log in to unmask]
URL: http://www.fil.ion.ucl.ac.uk/~wpenny/