Hi Alfonso,

Never mind, I figured it out! I changed the code to:

functionalz=cellstr(conn_dir('4D_uaf*.nii'));
functionalz=reshape(functionalz,[nsessions,nsubjects]); 

batch.Setup.functionals=repmat({{}},[nsubjects,1]);
for nsub=1:nsubjects
for nses=1:nsessions
batch.Setup.functionals{nsub}{nses}=functionalz{nses,nsub};
end
end

... and it worked. Thanks for all your help! :)