Thanks a lot for the fast responses.
Quickly with regard to the conditions: I want to use a factorial design,
so I believe I need to set up my conditions as indicated (6 total).
The way I am doing this right now is as follows: I include the block
onsets together with event onsets in the same condition file, i.e., if
one run has two blocks and five events per block, the input would look
14 16 21 22 24 25 136 137 145 149 150 158
30 0 0 0 0 0 30 0 0 0 0 0
Does this make sense?
MCLAREN, Donald wrote:
> 1) You have 9 conditions (3 blocks, 6 event-related conditions).
> 2) Modeling blocks: conditons with a duration the length of the block.
> 3) Modeling events: conditions with a duration of 0, if the event is
> less than 1s; otherwise you want to use the event duration.
> 4) Both blocks and events are convolved with the HRF. I am not sure how
> to select different HRF models for the blocks versus events, perhaps
> someone else knows.
> 5) Do not model baseline periods are null events.
> 6) Again, it might be good to have different functions for blocks and
> events, but I'm not sure how to implement this in SPM.
> On Tue, Mar 24, 2009 at 12:50 PM, Esther Fujiwara <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
> For a mixed blocked/event-related study, I would like to model
> blocks and
> events together. If I understand Visscher et al. [NeuroImage 19 (2003)
> 1694–1708] correctly, I would need to model/deconvolve blocks and events
> with different functions (blocks: gamma/boxcar; events: delta
> regressors at
> time zero and additional regressors for each of the following time
> covering 14-20 seconds total), but I am unsure how to do this with SPM5.
> My design has 3 block-types (ABC) and two event-types (1,2),
> resulting in a
> factorial design: 1A, 1B, 1C, 2A, 2B, 2C. (=6 conditions). The 60s
> are separated by 30s baseline blocks and I have additional null events
> within task blocks.
> 1) Do I need to select different functions and if so how?
> 2) How would I model the additional time points explicitly? And what
> is the
> difference between including the events as 'conditions' or 'regressors'?
> 3) Do I need to model baseline blocks and/or null trials?
> Thanks for any advice!
> Best Regards, Donald McLaren
> D.G. McLaren
> University of Wisconsin - Madison
> Neuroscience Training Program
> Office: (608) 265-9672
> Lab: (608) 256-1901 ext 12914
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