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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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🏛️國立陽明交通大學機構典藏

Author: search.filters.author.Ko, Li-WeiSubject: search.filters.subject.ICA

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Now showing 1 - 5 of 5
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    EEG-based Cognitive State Monitoring and Predition by Using the Self-Constructing Neural Fuzzy System
    (2010)
    Lin, Fu-Chang
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    Ko, Li-Wei
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    Chen, Shi-An
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    Chen, Ching-Fu
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    Lin, Chin-Teng
    Driver's cognitive state monitoring has been implicated as a causal factor for the safety driving issue, especially when the driver fell asleep or distracted in driving. In our past studies, we found that the EEG power spectrum changes were highly correlated with the driver's driving behavior performance. In this study, we attempt to construct an EEG-based self-constructing neural fuzzy system to monitor and predict the driver's cognitive state. The difficulties in developing such a system are lack of significant index for detecting drowsiness and the interference of the complicated noise in a realistic and dynamic driving environment. Our experimental results including correlation and prediction show that the performances of our proposed system are significantly higher than using the traditional neural networks. Besides, the proposed EEG-based self-constructing neural fuzzy system can be generalized and applied in the subjects' independent sessions. This unique advantage can be widely used in the real-life applications.
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    Estimating the Level of Motion Sickness Based on EEG Spectra
    (2011)
    Ko, Li-Wei
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    Wei, Chun-Shu
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    Jung, Tzyy-Ping
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    Lin, Chin-Teng
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    電機工程學系
    Motion sickness (MS) is a normal response to real, perceived, or even anticipated movement. People tend to get motion sickness on a moving boat, train, airplane, car, or amusement park rides. Although many motion sickness-related biomarkers have been identified, but how to estimate human's motion sickness level (MSL) is a big challenge in the operational environment. Traditionally, questionnaire and physical check are the common ways to passively evaluate subject's sickness level. Our past studies had investigated the EEG activities correlated with motion sickness in a virtual-reality based driving simulator. The driving simulator comprised an actual automobile mounted on a Stewart motion platform with six degrees of freedom, providing both visual and vestibular stimulations to induce motion-sickness in a manner that is close to that in daily life. EEG data were acquired at a sampling rate of 500 Hz using a 32-channel EEG system. The acquired EEG signals were analyzed using independent component analysis (ICA) and time-frequency analysis to assess EEG correlates of motion sickness. Subject's degree of motion-sickness was simultaneously and continuously reported using an onsite joystick, providing non-stop psychophysical references to the recorded EEG changes. We found that the parietal, motor, occipital brain regions exhibited significant EEG power changes in response to vestibular and visual stimuli. Based on these findings and experimental results, this study aims to develop an EEG-based system to estimate subject's motion sickness level upon the EEG power spectra from motion-sickness related brain areas. The MS evaluation system can be applied to early detection of the subject's motion sickness and prevent its uncomfortable syndromes in our daily life. Furthermore, the experiment results could also lead to a practical human-machine interface for noninvasive monitoring of motion sickness of drivers or passengers in real-world environments.
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    Alpha modulation in parietal and retrosplenial cortex correlates with navigation performance
    (2012-01-01)
    Chiu, Te-Cheng
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    Gramann, Klaus
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    Ko, Li-Wei
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    Duann, Jeng-Ren
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    Jung, Tzyy-Ping
    The present study investigated the brain dynamics accompanying spatial navigation based on distinct reference frames. Participants preferentially using an allocentric or an egocentric reference frame navigated through virtual tunnels and reported their homing direction at the end of each trial based on their spatial representation of the passage. Task-related electroencephalographic (EEG) dynamics were analyzed based on independent component analysis (ICA) and subsequent clustering of independent components. Parietal alpha desynchronization during encoding of spatial information predicted homing performance for participants using an egocentric reference frame. In contrast, retrosplenial and occipital alpha desynchronization during retrieval covaried with homing performance of participants using an allocentric reference frame. These results support the assumption of distinct neural networks underlying the computation of distinct reference frames and reveal a direct relationship of alpha modulation in parietal and retrosplenial areas with encoding and retrieval of spatial information for homing behavior.
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    Implementation of a Motion Sickness Evaluation System Based on EEG Spectrum Analysis
    (2011)
    Wei, Chun-Shu
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    Chuang, Shang-Wen
    ;
    Wang, Wan-Ru
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    Ko, Li-Wei
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    Jung, Tzyy-Ping
    Motion sickness is a normal response to real, perceived, or even anticipated movement. People tend to get motion sickness on a moving boat, train, airplane, car, or amusement park rides. Motion sickness occurs when the body, the inner ear, and the eyes send conflicting signals to the brain. Sensory conflict theory that came about in the 1970's has become the most widely accepted theorem of motion-sickness among scientists [1]. The theory proposed that the conflict between the incoming sensory inputs could induce motion-sickness. However, some new research studies have appeared to tackle the issue of the vestibular function in central nervous system (CNS). In the previous human subject studies, researchers attempt to confirm the brain areas involved in the conflict in multi-modal sensory systems by means of clinical or anatomical methods. Our past studies had investigated the EEG activities correlated with motion sickness in a virtual-reality based driving simulator. We found that the parietal, motor, occipital brain regions exhibited significant EEG power changes in response to vestibular and visual stimuli. Based on these experimental results, we attempt to implement an EEG-based evaluation system to estimate subject's motion sickness level upon the major EEG power spectra from these motion sickness related brain area in this study. The evaluation system can be applied to early detect the subject's motion sickness level and prevent the uncomfortable syndromes occurred in advance in our daily life.
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    EEG activities of dynamic stimulation in VR driving motion simulator
    (2007)
    Lin, Chin-Teng
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    Ko, Li-Wei
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    Lin, Yin-Hung
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    Jung, Tzyy-Ping
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    Liang, Sheng-Fu
    The purpose of this study is to investigate Electroencephalography dynamics in response to kinesthetic stimuli during driving. We used a Virtual Reality driving simulator consisted of a hydraulic hexapod motion platform to create practical driving events. We compared the EEG dynamics in response to kinesthetic stimulus while the platform was in motion, to that while the platform was stationary. The scalp-recorded EEG channel signals were first separated into independent brain sources using Independent Component Analysis (ICA), and then studied with time-frequency analysis. Our results showed that independent brain processes near the somatomotor cortex exhibited alpha power decreases across sessions and subjects. Negative potentials phase-locked to the onsets of deviation events under motion conditions were observed in a central midline component. The results allow us to better understand different brain networks involved in driving, and provide a foundation for studying event-related EEG activities in the presence of kinesthetic stimuli.