Hi Dr. McLaren,

I'm running a pretty straightforward analysis looking at the change in effective connectivity between a seed (dorsolateral PFC, defined functionally from the group level contrast) and the rest of brain as a function of working memory load (low vs high). I'm running a gPPI analysis using the following script (copied at the bottom). The script has worked beautifully on 120 of 140 subjects. For the successful subjects the results look reasonable - showing greater connectivity between DLPFC and posterior parietal cortices as working memory load increases.

For 20 subjects, the script failed and I got the following error:
"Input structure is not correct."

There is nothing obviously different between the subjects who ran successfully and those who didn't (e.g. no difference in path structure, etc).

Any inkling what the problem could be?

Very grateful for your time,

Emily

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clear all
clc
%%%Change this if changing the seed
P.VOI='/autofs/space/lobulus_002/users/NEFS_aging/2back_N142/_PPI/Seed_ROIs/ROI_14_masked.nii';
P.Region='L_DLPFC';

%P.equalroi = 0;
%%%Creating a group folder
RegionName=evalc('P.Region');

%IMPORTANT!!! - The length of RegionName may change for different lengths of seed names
%for B_Nacc RegionName(9:14) %for B_Habenula RegionName(9:18) %for B_Caduate RegionName(9:17)
P.GroupDir=['/autofs/space/lobulus_002/users/NEFS_aging/2back_N142/_PPI/Group_Analyses/', RegionName(9:15)];
Group_Dir = P.GroupDir;
if ~exist(Group_Dir, 'dir'),
mkdir(Group_Dir);
end

%%%Subject list
Subjects={'B12871-ef'};

%%%Those are all PPI related variables that are identical for all subjects
P.Estimate=1;
P.contrast=0;
P.extract='eig';
P.Tasks={'1' '2back' 'XTask'};
P.Weights=[];
P.method='cond';
P.analysis='psy';
P.CompContrasts=1;
P.Weighted=0;

%%%Loop between subjects
for i=1:length (Subjects);
SubjName = evalc('Subjects(i)');
P.subject=SubjName(15:23);
P.directory=['/autofs/space/lobulus_002/users/NEFS_aging/',SubjName(15:23),'/nifti/2back/2back_motionmodel']
try

%&&Directory of SPM.mat files
SPM_Dir=P.directory;
cd(SPM_Dir);
%%%Do the gPPI
PPPI(P);
catch
disp(['Failed: ' Subjects{i}])
end
end