Hi,

Here are more sophisticated method to search for effective connectivity:

-Smith, S. M., Miller, K. L., Salimi-Khorshidi, G., Webster, M., Beckmann,
C. F., Nichols, T. E., ... & Woolrich, M. W. (2011). Network modelling
methods for FMRI. Neuroimage, 54(2), 875-891.
-Ramsey, J. D., Hanson, S. J., & Glymour, C. (2011). Multi-subject search
correctly identifies causal connections and most causal directions in the
DCM models of the Smith et al. simulation study. NeuroImage, 58(3),
838-848.
-Ramsey, J. D., Sanchez-Romero, R., & Glymour, C. (2014). Non-Gaussian
methods and high-pass filters in the estimation of effective connections.
NeuroImage, 84, 986-1006.
-Mumford, J. A., & Ramsey, J. D. (2013). Bayesian Networks for fMRI: A
Primer. NeuroImage.

Ruben