Determination of ECoG information flow activity based on Granger causality and Hilbert transformation
Determination of ECoG information flow activity based on Granger causality and Hilbert transformation
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DOI：
10.1016/j.cmpb.2013.08.011
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发表时间：
2013-12-01
影响因子：
6.1
通讯作者：
Mendi, Engin
中科院分区：
文献类型：
--
作者：
Demirer, R. Murat;Ozerdem, Mehmet Sirac;Mendi, Engin
分析大脑不同区域间的定向信息流模式对于研究皮层脑电图（ECoG）与心理活动的关系具有重要意义。目的是研究和评价初级运动皮层不同频率的信息流活动。我们采用格兰杰因果关系来捕捉大脑皮层上记录电极位点之间的传播路径和方向的未来状态。一个网格完全覆盖了右运动皮层，因为它的大小（大约）。8 cm x 8 cm），但网格区域延伸至周围皮质区域。在实验过程中，受试者被要求想象进行两项活动：左手小指的运动和/或舌头的运动。在这些试验期间，使用放置在对侧（右侧）运动皮层上的8 x 8（0.016-300 Hz频带）ECoG铂电极网格记录脑电活动的时间序列。为了检测电极之间的信息流活动和通信频率，我们提出了一种基于以下步骤的方法：（i）计算分析时间序列，例如从希尔伯特变换获得的幅度和相位差，（ii）在滑动窗口上选择对于所关注的时间序列的电极对具有最高相互依赖性的频率，在滑动窗口中，我们假设时间序列是平稳的，（iii）计算具有选定频率的每一对的格兰杰因果关系值。成功地确定并显示了网格中电极之间的信息流（因果影响）活动和通信频率。假设对于相同的图案，网格中电极之间的信息流活动和通信频率近似相同。成功地利用格兰杰因果关系和希尔伯特变换检测皮层下不同区域间皮层脑电各成分的传播路径和方向，能够成功地确定神经元群体之间的信息流（因果影响）活动和通信频率。(C)2013爱思唯尔爱尔兰有限公司版权所有。
Analysis of directional information flow patterns among different regions of the brain is important for investigating the relation between ECoG (electrocorticographic) and mental activity. The objective is to study and evaluate the information flow activity at different frequencies in the primary motor cortex. We employed Granger causality for capturing the future state of the propagation path and direction between recording electrode sites on the cerebral cortex. A grid covered the right motor cortex completely due to its size (approx. 8 cm x 8 cm) but grid area extends to the surrounding cortex areas. During the experiment, a subject was asked to imagine performing two activities: movement of the left small finger and/or movement of the tongue. The time series of the electrical brain activity was recorded during these trials using an 8 x 8 (0.016-300 Hz band with) ECoG platinum electrode grid, which was placed on the contralateral (right) motor cortex. For detection of information flow activity and communication frequencies among the electrodes, we have proposed a method based on following steps: (i) calculation of analytical time series such as amplitude and phase difference acquired from Hilbert transformation, (ii) selection of frequency having highest interdependence for the electrode pairs for the concerned time series over a sliding window in which we assumed time series were stationary, (iii) calculation of Granger causality values for each pair with selected frequency. The information flow (causal influence) activity and communication frequencies between the electrodes in grid were determined and shown successfully. It is supposed that information flow activity and communication frequencies between the electrodes in the grid are approximately the same for the same pattern. The successful employment of Granger causality and Hilbert transformation for the detection of the propagation path and direction of each component of ECoG among different subcortex areas were capable of determining the information flow (causal influence) activity and communication frequencies between the populations of neurons successfully. (C) 2013 Elsevier Ireland Ltd. All rights reserved.