Hello all,
I an trying to transition form epoch-based to event-related studies to
measure a presumed transient response to sensory stimulation. I have
been using SPM99 to help design the paradigm but I have several
questions that I hopw you can help with.
1. When specifying a design with the stochastic function, how do you
decide which basis function to choose? As I am sure you are aware, there
are several gamma and fourier choices.
2. As the help suggests, modulated designs are better than stationary
designs. How can I decide if I need a modulated design and if so, how do
I decied what parameters I enter for such a design?
3. Choosing an appropriate SOA escapes me. I have searched the mail list
and was unable to find the information to help me decide on an
appropriate SOA. Could you tell me how to determine an SOA most
appropriate for any particular study.
4. Finally, once the design matrix is produced, how do I get the actual
onste times for each event so that I can program my stimulus delivery
software? I am aware that spm_get_ons calculates the delta functions but
I have not been able to obtain these numbers.
Any help that you can provide will be appreciated.
Paul Laurienti
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