Đang chuẩn bị liên kết để tải về tài liệu:
Báo cáo sinh học: " Research Article Estimation of Time-Varying Coherence and Its Application in Understanding Brain Functional Connectivity"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Estimation of Time-Varying Coherence and Its Application in Understanding Brain Functional Connectivity | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 390910 11 pages doi 10.1155 2010 390910 Research Article Estimation of Time-Varying Coherence and Its Application in Understanding Brain Functional Connectivity Cheng Liu 1 William Gaetz 2 and Hongmei Zhu EURASIP Member 1 1 Department of Mathematics and Statistics York University Toronto ON Canada M3J1P3 2 Biomagnetic Imaging Laboratory Children s Hospital of Philadelphia Philadelphia PA 19104 USA Correspondence should be addressed to Hongmei Zhu hmzhu@yorku.ca Received 2 January 2010 Accepted 24 June 2010 Academic Editor L. F. Chaparro Copyright 2010 Cheng Liu et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Time-varying coherence is a powerful tool for revealing functional dynamics between different regions in the brain. In this paper we address ways of estimating evolutionary spectrum and coherence using the general Cohen s class distributions. We show that the intimate connection between the Cohen s class-based spectra and the evolutionary spectra defined on the locally stationary time series can be linked by the kernel functions of the Cohen s class distributions. The time-varying spectra and coherence are further generalized with the Stockwell transform a multiscale time-frequency representation. The Stockwell measures can be studied in the framework of the Cohen s class distributions with a generalized frequency-dependent kernel function. A magnetoencephalography study using the Stockwell coherence reveals an interesting temporal interaction between contralateral and ipsilateral motor cortices under the multisource interference task. 1. Introduction Previous studies in neuroscience have shown that cortico-cortical interactions play a crucial role in the performance of cognitive tasks. .