标题: 探讨驾驶人员脑内网路之有效连结在不同意识状态下的改变
Study of Effective Connectivity in Human Brain Network under Drivers’ Different Arousal Levels
作者: 王洁明
Wang, Jie-Ming
林进灯
邵家健
Lin, Chin-Teng
Zao, John K.
生医工程研究所
关键字: 脑电波;开车打瞌睡;专注力;有效连结;Granger 因果关系;独立成分分析;EEG;Drowsy driving;Attention;Effective connectivity;Granger causality;Independent component analysis
公开日期: 2011
摘要: 在长时间而单调的开车环境下,驾驶人员很容易出现打瞌睡的情形。在许多的车祸事故当中,开车打瞌睡被认为是主要的原因之一。为了预防开车打瞌睡所造成的严重后果,许多研究致力于寻找打瞌睡相关的脑波变化,进而设计相关之演算法以开发瞌睡侦测相关的设备。然而,对于大脑在意识转变的过程中不同脑区间的互动却很少被讨论到。因此,本论文着重于探讨驾驶人员从清醒到瞌睡以及瞌睡后清醒的过程中脑内讯号传递网络的改变。本研究共有十二位受试者参与模拟夜间高速公路动态的虚拟实验,实验中会给予受试者事件相关的偏移任务。受试者的脑波讯号会藉由独立成分分析取得感兴趣的脑区,再以部分直接相关性(partial directed coherence, PDC)的分析方法探讨不同意识状态下脑内之有效连结的改变。研究结果显示,当受试者处于清醒的驾驶状态下,在α频带的后顶叶皮质会影响纹外皮层;另外,也发现到在θ以及α频带的纹外皮层会去影响前额叶皮质。这两条讯息流的出现代表视觉空间专注(visuospatial attention)的维持及对事件的预测。在转换时期的驾驶状态下,从前额叶皮质传出的讯息流是最强的(所有的频带现象一致),这代表受试者似乎需要花更多的努力去维持专注力。其中,由前额叶皮质传到前运动皮质的讯息流有显着的上升,我们推测是与受测者将专注力转移到维持眼睛的动作有关。当受测者进入瞌睡时期的驾驶行为后,与专注及注意相关的讯息流消失了,这代表受测者已经没有能力专注在开车事件上。另外在瞌睡后清醒的时期,虽然受测者的反应时间与清醒时期相同,但是从脑内网络的角度来看,大脑的活动已经明显的改变了。有趣的是,瞌睡后清醒时期的脑内网络与转换时期的脑内网络非常相似。
Drowsy driving is one of the major factors leading to traffic accidents, especially occurring in a monotonous environment, the night-time driving, or after long-term driving. To avoid the occurrence of drowsy driving, a considerable number of studies attempted to develop an in-vehicle protocol via monitoring the electroencephalogram (EEG) features of drowsiness. One of the promising measures to evaluate the cognitive state is the change of EEG power spectra. However, most of previous literatures focused on the neurocognitive characteristics on separate brain regions, the human brain network in response to the cognitive transition from alertness to drowsiness is yet poorly understood. To address this issue, this study applied independent component analysis and partial directed coherence to show the change of effective connectivity between distributed brain regions under different vigilance levels, including alertness, transition, drowsiness, and abrupt-awake, during the simulated driving. The results of alpha coupling showed that the extrastriate cortex sent a causal outflow to the anterior region and received a causal inflow from the posterior region while being alert, compared to being drowsy. Regarding the transition state, the anterior region played a major source to affect the rest of the brain region with a cross-frequency coupling, and the connectivity magnitude had a relatively large causality, compared to other vigilance levels. Most of causal magnitudes declined as subjects progressed into a drowsy state. Interestingly, the subjects enabled a short reaction time in response to traffic events when they abruptly awakening from the drowsy state, however, the causal magnitude climbed to the level as the transition state, rather than the alert state.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079930503
http://hdl.handle.net/11536/49992
显示于类别:Thesis