Are you talking about doing parametric modulations? What's your task?
From: SPM (Statistical Parametric Mapping) [[log in to unmask]] On Behalf Of Cinly Ooi [[log in to unmask]]
Sent: Tuesday, July 26, 2011 3:28 PM
To: [log in to unmask]
Subject: [SPM] Varying the weight for 1st level design matrix

Dear All,

Someone asked me to run a first level analysis where instead of a standard boxcar or event design, I have a weighting value associated with each TR. I believe what I have to do is to set the onset time and duration as usual, then assign a weight to each onset time.i.e., instead of accepting the standard weight of '1,1,1,1', I want to specify them as '2,1,1,2' for example.

Since each session will have its own unique weights, for ease of data entry, I will be reading the weights from files and will be processing the data using Rhodri's AA.

A bit of digging into AA shows that  I have to setup this up using SPM.Session(s), and I believe SPM.Session(s).U is the candidate to accept the weights. My problem is, after reading spm_FMRI_design.m, I still have no clue how to set the weight.

How do I go about setting the weights? These weights are expected to be convoluted with HRF later.

In case it helps, it is one weight per volume. So since I have 224 volumes in the fMRI time series, I will have 224 weights to put in.

Many thanks in advance and hope to hear from you soon.

Best Regards,