Hi (sorry for any double posting),
I have a few questions about analysing a mixed block/event-related design in
the same model. If I understand Visscher et al. correctly (NeuroImage 19
(2003) 1694–1708), blocks and events are modeled with different functions
(gamma function vs. separate delta regressors for each time point following
the event, covering 14-20 s post-event).
My design has three blocks (ABC) and 2 event-types (1,2), presented in each
block, i.e., a 2x3 design like this: 1A,1B,1C,2A,2B,2C. Task blocks are 60
seconds long, with 30s baseline blocks. Events (within task blocks) are
mixed with null events.
1) If I want to model events and blocks in the same model using SPM5, do I
need to use different functions for events and blocks? How/where do I do
this in SPM5?
2) How do I model the post-event time frames explicitly?
3) What is the difference between modeling a 'condition' and 'regressor'?
And do I need to model baseline blocks and/or null trials explicitly?
Thank you very much for any advice.