I am attempting to use a FIR model and but keep running into problems at the Estimation stage. My aim is to model brain activity elicited while participants viewed movies that were 13 TRs long (19.5sec). I was hoping to model the response over 13 time bins of width equal to the TR. The experiment is a 5 by 2 factorial design with 1-6 events per cell (cells are unequal because participants made errors on some trials). To do run this analysis, I have modelled each movie onset (in scans), set the duration = 19.5sec and set the FIR order = 13 with width = 1.5sec. I have not factored in any kind of temporal lag.

When I try to generate the estimates for this model I receive the following error.

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Running job #1

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Running 'Model estimation'

SPM8: spm_spm (v4191) 15:05:43 - 21/11/2011

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Initialising parameters : ...done

Plane 22/22 , block 3/3 : ...done

Temporal non-sphericity (over voxels) : ...ReML estimation

ReML Block 1

ReML Iteration 1 : ...6.158166e+001 [+4.25]

ReML Iteration 2 : ...9.398060e-001 [+4.50]

ReML Iteration 3 : ...1.115044e-001 [+4.75]

ReML Iteration 4 : ...1.011155e-002 [+5.00]

ReML Block 2

ReML Iteration 1 : ...8.322690e+001 [+4.25]

ReML Iteration 2 : ...2.335397e-001 [+4.50]

ReML Iteration 3 : ...1.942946e-002 [+4.75]

SPM8: spm_spm (v4191) 15:08:03 - 21/11/2011

========================================================================

Initialising parameters : ...done

Output images : ...initialised

Plane 22/22 , block 3/3 : ...done

Spatial non-sphericity (over scans) : ...done

Saving results : ...done

Completed : 15:11:40 - 21/11/2011

...use the results section for assessment

Failed 'Model estimation'

Improper index matrix reference.

In file "C:\Program Files (x86)\MATLAB\R2009a Student\toolbox\spm8\spm_contrasts.m" (v4185), function "spm_contrasts" at line 66.

In file "C:\Program Files (x86)\MATLAB\R2009a Student\toolbox\spm8\config\spm_run_fmri_est.m" (v4022), function "spm_run_fmri_est" at line 60.

The following modules did not run:

Failed: Model estimation

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Any help would be greatly appreciated.

Sincerely,

Bronson Harry