Gopikrishna Deshpande1, Xiaoping Hu1
1Department of Biomedical Engineering,
Georgia Institute of Technology and Emory University, Atlanta, GA, United
States
The
hemodynamic response of fMRI is known to vary across brain regions. This has
the potential to confound inferences about neuronal causality obtained from
Granger causality analysis of fMRI. We investigated this aspect in a
multivariate model using a simulated neuronal system. The results suggest
that Granger causality inferred from
fMRI data had accuracies well above chance and up to 90%, provided the
data had low measurement noise, was sampled at a TR less 2 s, the causal
influences were strong and the hemodynamic delay variation is within its
normal physiological range.