Estimating dynamic cortical connectivity from motor imagery EEG using KALMAN smoother & EM algorithm

S. Balqis Samdin, Chee Ming Ting, Sh Hussain Salleh, Mahyar Hamedi, A. B.Mohd Noor

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

10 Citations (Scopus)


This paper considers identifying effective cortical connectivity from scalp EEG. Recent studies use time-varying multivariate autoregressive (TV-MAR) models to better describe the changing connectivity between cortical regions where the TV coefficients are estimated by Kalman filter (KF) within a state-space framework. We extend this approach by incorporating Kalman smoothing (KS) to improve the KF estimates, and the expectation-maximization (EM) algorithm to infer the unknown model parameters from EEG. We also consider solving the volume conduction problem by modeling the induced instantaneous correlations using a full noise covariate. Simulation results show the superiority of KS in tracking the coefficient changes. We apply two derived frequency domain measures i.e. TV partial directed coherence (TV-PDC) and TV directed transfer function (TV-DTF), to investigate dynamic causal interactions between motor areas in discriminating motor imagery (MI) of left and right hand. Event-related changes of information flows around beta-band, in a unidirectional way between left and right hemispheres are observed during MI. A difference in inter-hemispheric connectivity patterns is found between left and right-hand movements, implying potential usage for BCI.

Original languageEnglish
Title of host publication2014 IEEE Workshop on Statistical Signal Processing, SSP 2014
PublisherIEEE, Institute of Electrical and Electronics Engineers
Number of pages4
ISBN (Print)9781479949755
Publication statusPublished - 2014
Externally publishedYes
EventIEEE Workshop on Statistical Signal Processing (SSP) 2014 - Gold Coast, Australia
Duration: 29 Jun 20142 Jul 2014 (Proceedings)


WorkshopIEEE Workshop on Statistical Signal Processing (SSP) 2014
Abbreviated titleSSP 2014
CityGold Coast
Internet address


  • dynamic cortical connectivity
  • EEG
  • EM algorithm
  • Multivariate autoregressive model
  • state-space model

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