I would recommend doing the following:
1. Normalize each subject's data using the following Matlab code:
function t1 = normalize(t1);
t1 = (t1 - mean(t1)) / max(abs((t1 - mean(t1))));
2. Then take the number of scans (e.g. 345) and take the max EDA value for
that TR using the following code.
You can do that with this code:
EDA=t1;
EDA_TR=reshape(t1, [#_of_values_per_TR #_of_TRs])
Max_EDA=max(EDA_TR)
3. If you are using motion as a regressor (6 values), these value can be
entered as the 7th regressor.
If you are more experienced with Matlab you can use the Time Series
functions and can be done without code (except the normalize step).
Hope this helps.
Steve
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On
Behalf Of <Michele> <Butti>
Sent: Thursday, June 07, 2007 3:43 AM
To: [log in to unmask]
Subject: [SPM] fMRI and physiological measurement
Dear all,
I would like to insert as extra regressors in a fMRI analysis some
physiological measurement acquired during the scanning procedure.
Precisely, we recorded skin conductance and ECG. Making inference on
these regressors should give information about liner correlation about
physiological data and cerebral activation.
I was wondering if this procedure can mask a brain activation tested
with a regressor explaining the experiment.
Thanks to all,
Michele Butti
|