Thank you so much Doug! I just have one more question:

Before convolving regressors with HRF, I looked at X matrix and noticed that the values of regressors have been changed/scaled. For example, the original values in a regressor file are:

134.8300 0 141.1200 0 91.5310 0 96.1870 0

But they have been apparently shifted by a constant value in the X matrix:

91.8168 -43.0132 98.1068 -43.0132 48.5178 -43.0132 53.1738 -43.0132

Why is there such a change in the regressor values?

Thanks, Reza

You can use the following matlab code. You can ignore the warning printed after the toepliz operation. The OriginalRegressor should be a vector of length Ntp, then write out the NewRegressor to a new external regressor file.

TR=2; % seconds

Ntp=100; t = TR*[0:Ntp-1]';

h = fast_spmhrf(t);

a = zeros(Ntp,1); a(1) = 1; X = toeplitz(h,a);

NewRegressor = X*OriginalRegressor;

On 02/21/2017 04:02 PM, Reza Rajimehr wrote:

• Hi Doug,

*>>* Since our external regressors are stimulus-related (e.g. mean *>* luminance of stimuli), we need to convolve them with a hemodynamic *>* response function. In mkanalysis-sess, we have used -spmhrf 0 to model *>* conditions. Is there a code or Matlab script for HRF convolution, so *>* that we apply exactly the same spmhrf function for modeling the *>* external regressors? *>>* Thanks, *>* Reza *>>* No, they are not *>>>* On 02/17/2017 05:09 PM, Reza Rajimehr wrote: *>* >/During the functional analysis in FS-FAST, are the external regressors />/convolved with the hemodynamic response function? />//>/Thanks, />/Reza />//>//>/_______________________________________________ />/Freesurfer mailing list />/Freesurfer at nmr.mgh.harvard.edu http://nmr.mgh.harvard.edu *>* <https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer> />/https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer / *>* -- *>* Douglas N. Greve, Ph.D. *>* MGH-NMR Center *>* greve at nmr.mgh.harvard.edu http://nmr.mgh.harvard.edu *>* <https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer> *>* Phone Number: 617-724-2358 *>* Fax: 617-726-7422 *>>* Bugs:surfer.nmr.mgh.harvard.edu/fswiki/BugReporting http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting *>* <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> *>* FileDrop:https://gate.nmr.mgh.harvard.edu/filedrop2 https://gate.nmr.mgh.harvard.edu/filedrop2 *>* www.nmr.mgh.harvard.edu/facility/filedrop/index.html http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html *>* <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> *>* Outgoing:ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ *>>>* _______________________________________________ *>* Freesurfer mailing list *>* Freesurfer at nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer *>* https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer *