The dynamic programming high-order Dynamic Bayesian Networks learning for identifying effective connectivity in human brain from fMRI

- A novel approach proposing use of High-order Dynamic Bayesian Networks (HO-DBNs) for identifying Effective connectivity (EC) is presented.
- A fundamental problem faced in the structure learning of HO-DBN is low accuracy and high computational burden.
- The framework uses dynamic programming principle while exploiting properties of scoring function.
- This guarantees globally optimal solution for the structure learning problem.
- This overcomes the disadvantage of low accuracy and high computational burden of existing algorithms used for EC.

BackgroundDetermination of effective connectivity (EC) among brain regions using fMRI is helpful in understanding the underlying neural mechanisms. Dynamic Bayesian Networks (DBNs) are an appropriate class of probabilistic graphical temporal-models that have been used in past to model EC from fMRI, specifically order-one.New-methodHigh-order DBNs (HO-DBNs) have still not been explored for fMRI data. A fundamental problem faced in the structure-learning of HO-DBN is high computational-burden and low accuracy by the existing heuristic search techniques used for EC detection from fMRI. In this paper, we propose using dynamic programming (DP) principle along with integration of properties of scoring-function in a way to reduce search space for structure-learning of HO-DBNs and finally, for identifying EC from fMRI which has not been done yet to the best of our knowledge. The proposed exact search-&-score learning approach HO-DBN-DP is an extension of the technique which was originally devised for learning a BN's structure from static data (Singh and Moore, 2005).ResultsThe effectiveness in structure-learning is shown on synthetic fMRI dataset. The algorithm reaches globally-optimal solution in appreciably reduced time-complexity than the static counterpart due to integration of properties. The proof of optimality is provided.ComparisonThe results demonstrate that HO-DBN-DP is comparably more accurate and faster than currently used structure-learning algorithms used for identifying EC from fMRI. The real data EC from HO-DBN-DP shows consistency with previous literature than the classical Granger Causality method.ConclusionHence, the DP algorithm can be employed for reliable EC estimates from experimental fMRI data.

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