title: Analyzing brain networks with PCA and conditional Granger causality.
abstract: Identifying directional influences in anatomical and functional circuits presents one of the greatest challenges for understanding neural computations in the brain. Granger causality mapping (GCM) derived from vector autoregressive models of data has been employed for this purpose, revealing complex temporal and spatial dynamics underlying cognitive processes. However, the traditional GCM methods are computationally expensive, as signals from thousands of voxels within selected regions of interest (ROIs) are individually processed, and being based on pairwise Granger causality, they lack the ability to distinguish direct from indirect connectivity among brain regions. In this work a new algorithm called PCA based conditional GCM is proposed to overcome these problems. The algorithm implements the following two procedures: (i) dimensionality reduction in ROIs of interest with principle component analysis (PCA), and (ii) estimation of the direct causal influences in local brain networks, using conditional Granger causality. Our results show that the proposed method achieves greater accuracy in detecting network connectivity than the commonly used pairwise Granger causality method. Furthermore, the use of PCA components in conjunction with conditional GCM greatly reduces the computational cost relative to the use of individual voxel time series.
authors.affiliation: Key Laboratory of Child Development and Learning Science, Southeast University, Ministry of Education, Nanjing, People's Republic of China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Chen
authors.forename: Mingzhou
authors.initials: M
authors.lastname: Ding
authors.forename: Paul
authors.initials: P
authors.lastname: Wright
authors.forename: Zuhong
authors.initials: Z
authors.lastname: Lu
authors.forename: Yijun
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000465:Algorithms; D000679:Amygdala / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D003198:Computer Simulation; D004644:Emotions / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008962:Models, Theoretical; D009434:Neural Pathways / Q000502:physiology; D025341:Principal Component Analysis