• Journal of the Ergonomics Society of Korea
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• v.27 no.2
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• pp.9-14
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• 2008

Coherence can be used to evaluate the functional cortical connections between the motor cortex and muscle. This study is to find coherence between EEG (electroencephalogram) and EMG (electromyogram) evoked by movement of a hand. Seven healthy participants were asked to perform thirty repetitive movement of right hand for ten seconds with rest for ten seconds. Specific feature of EEG components has been extracted by ICA (independent component analysis) and coherence between EEG and EMG was analyzed from data measured EEG in five local areas around central part of head and EMG in flexer carpri radialis muscle during grabbing movement. Coherence between EEG and EMG was successfully obtained at 0.025 confidence limit during hand movement and showed significant difference between rest and movement at 13-18Hz.

• Journal of Biomedical Engineering Research
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• v.31 no.1
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• pp.27-32
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• 2010

Noninvasive detection of patients with probable Alzheimer's disease (AD) is of great importance for assisting a medical doctor's decision for early treatment of AD patients. In the present study, we have extracted quantitative electroencephalogram (qEEG) variables, which can be potentially used to diagnose AD, from resting eyes-closed continuous EEGs of 22 AD patients and 27 age-matched normal control (NC) subjects. We have extracted qEEG variables from mean phase coherence (MPC) and EEG coherence, evaluated for all possible combinations of electrode pairs. Preliminary trials to discriminate the two groups with the extracted qEEG variables demonstrated that the use of MPC as a supplementary or alternative measure for the EEG coherence may enhance the accuracy of noninvasive diagnosis of AD.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.330-334
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• 2009

본 연구는 뇌의 편측 영역 에서의 EEG(Electroencephalography) coherence 로 손동작 의도를 예측하고자 하는 연구이다. 손 동작 예측을 위한 실험에 신체에 이상이 없는 6 명의 피실험자가 참여 하였다. 실험은 데이터 트레이닝 6 분과 동작 의도 판단 6 분으로 진행되었으며 무작위 순서로 손 동작을 지시한 후 편측적 영역 5 개 지점의 EEG 와 동작 시점을 알기 위한 오른손 EMG(Electromyography)를 측정하였다. 측정된 EEG 데이터를 분석하기 위해 주파수 별 Alpha 와 Beta 를 분류하였고 EMG 신호를 기준으로 동작과 휴식으로 분류된 Alpha 와 Beta 데이터를 5 개의 측정 영역별 Coherence 분석을 하였다. 그 결과 동작과 휴식을 구분할 수 있는 통계적으로 유효한 EEG Coherence 영역을 통하여 동작 판단을 할 수 있음을 확인하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.117-120
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• 2009

본 연구는 손동작을 하였을 때 집중력이 EEG 코히런스(coherence)에 미치는 영향을 분석하였다. 신체에 이상이 없는 대학생 8 명이 시각 자극으로 제시되는 운동 작업을 지시하는 실험에 참여하였다. 실험 중 실시간으로 오른손의 요측 수굴근에 센서를 부착하여 EMG 를 측정하였고 국제 10-20 측정법에 의거한 C3 지점과 상하좌우로 2.5cm 떨어진 지점에 5 개의 전극을 부착하여 EEG 를 측정하였다. 운동영역간의 또는 운동영역과 비운동영역 사이의 코히런스 분석을 통하여 동작과 휴식을 구분해 주는 유의한 결과를 확인할 수 있었으나 개인에 따른 차이를 보였다. 유의한 차이를 보이는 코히런스 채널 쌍의 개수에 의해 강한 코히런스와 약한 코히런스로 그룹화 할 수 있었다. 개인별로 차이가 있는 EEG 코히런스의 결과는 동작시의 채널 별 EEG 의 상대적 출현량의 결과와 동일한 패턴을 가진 것으로 확인되어 주의력에 의한 영향임을 알 수 있었다.

• Journal of the Ergonomics Society of Korea
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• v.29 no.2
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• pp.189-196
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• 2010

The study is to find relative EEG power spectrum and pattern of coherence discriminating attentive and inattentive hand movements. Eight undergraduate students aged from 20 to 27 who had not hand disability participated in this study. Participants were asked to perform visuo-motor task. EEG was measured at C3 in 10~20 international system and four areas orthogonally directed 2.5cm away from C3. Significant result discriminating movement and rest was found through coherence analysis between movement areas or movement area and non-movement area, but was individually different. Because it was anticipated that major factors caused by the differences among individuals were attributed to the attention of the subjects, relative power of alpha and beta bands was identified. As a result, significant relative powers of alpha and beta bands were found in a group of high coherence level, but were not found in a group of low level. Next, participants were divided into two groups according to relative powers of alpha and beta bands. The comparison between two groups was performed. As a result, the coherence of the alpha band in the attentive group was greater than that of the inattentive group. It was found that the coherence of the beta band in the inattentive group was happening. Therefore, individual differences of coherence were influenced by attention. The significant coherence patterns that could discriminate attentive movement and inattentive movement were found.

• Korean Journal of Biological Psychiatry
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• v.21 no.4
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• pp.151-160
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• 2014

Objectives Prenatal testosterone is known to influence both cerebral laterality and 2nd to 4th digit ratio (2D : 4D). Epigenetic changes are thought to play some role in it. We studied sex-related differences between 2D : 4D and cerebral laterality in patients with schizophrenia and controls to examine the effects of prenatal testosterone in the development of schizophrenia. Methods Forty one men (18 schizophrenic patients and 23 controls) and 40 women (17 schizophrenic patients and 23 controls) were recruited from one psychiatric hospital in Korea. The 2D : 4D and electroencephalographic (EEG) coherence in 19 channels (66 pairs of interhemispheric coherence and 54 pairs of intrahemispheric coherence) were measured. The sex-related statistical analyses between 2D : 4D and EEG coherence in controls and patients with schizophrenia were performed using multiple regression. Results In male patients, the relationship between 2D : 4D and right intrahemispheric EEG coherence showed mainly positive correlation in delta and theta frequency bands, while it showed negative correlation in male controls. In female patients, the relationship between 2D : 4D and interhemispheric EEG coherence showed stronger positive correlation in alpha and beta frequency bands, while it showed weaker positive correlation in female controls. Conclusions Low prenatal testosterone may play certain roles in altered correlation between 2D : 4D and cerebral laterality in schizophrenia and the development of schizophrenia by epigenetic mechanism.

• Science of Emotion and Sensibility
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• v.11 no.3
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• pp.357-364
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• 2008

This study is to find training effect on EEG(Electroencephalography) and EMG(electromyogram) evoked by repetitive movement of a hand. Five university students participated in this study and were asked to perform repetitive movement of right hand for 5 seconds with rest for 10 seconds. They repeated the movement for 48 minutes and for 5 days. EEG and EMG were measured according to every movement. Coherence between EEG and EMG and power spectrum of EEG were analyzed and were tried to observe their changes within a day and between days of the repetitive movement. Training effect according the time of the movement was significantly found in mu and beta frequencies in EEG. However, training effect was not significant between the days of the movement and also, not in coherence between EEG and EMG.

• Journal of Korean Elementary Science Education
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• v.25 no.2
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• pp.159-166
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• 2006

Changes in the brain activities following pre-service elementary teachers' learning hypothesis-generation were investigated using the analysis of EEG relative power and EEG coherence. In this study, the experimental group (n=16) were trained using learning methods for hypothesis-generation and the control group(n=16) were trained using learning methods for hypothesis-reception over the course of 8 weeks. EEG was measured before and following the learning process for both groups. Decreased theta ($4{\sim}7.9Hz$)/alpha 1 ($8{\sim}9.9Hz$) power and increased alpha 2 ($10{\sim}l2.9Hz$)/beta ($13{\sim}29.9Hz$)/gamma ($30{\sim}50Hz$) power were showed in the experimental group. Additionally, many changes in brian activities were observed for theta, beta and gamma coherence in the experimental group. In particular, fronto-parietal coherence increased in the experimental group. These differences in brain activities between the two groups suggest that the learning for subjects' hypothesis generation presumably leads to interesting changes in some types of brain activities in pre-service elementary teachers.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.221-229
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• 2004

The Continuous Wavelets Transform project signal f(t) to "Time-scale"plan utilizing the time varied function which called "wavelets". This Transformation permit to analyze scale time dependence of signal f(t) thus the local or global scale properties can be extracted. Moreover, the signal f(t) can be reconstructed stably by utilizing the Inverse Continuous Wavelets Transform. In this paper, the EEG signal is analyzed by wavelets coherence method and the De-noising procedure is represented.

• The Journal of Korean Physical Therapy
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• v.28 no.6
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• pp.398-407
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• 2016

Purpose: The purpose of this study was to examine the changes in electroencephalogram (EEG) coherence and brain wave activity for first-person perspective action observation (1AO) and third-person perspective action observation (3AO) of healthy subjects. Methods: Thirty healthy subjects participated in this study. EEG was simultaneously recorded during the Relax period, the 1AO, and the 3AO, with event-related desynchronization (ERD) and coherence connectivity process calculations for brain wave (alpha, beta and mu) rhythms in relation to the baseline. Results: Participants showed increased coherence in beta wave activity in the frontal and central areas (p<0.05), during the 1AO using right-hand activity. Conversely, the coherence of the alpha wave decreased statistically significantly decreased in the frontocentral and parieto-occipital networks during the observation of the 1AO and the 3AO. The ERD values were larger than 40% for both central regions but were slightly higher for the C4 central region. The high relative power of the alpha wave during 1AO and 3AO was statistically significantly decreased in the frontal, central, parietal, and occipital regions. However, the relative power of the beta wave during 1AO and 3AO was statistically significantly increased in the parietal and occipital regions. Especially during 1AO, the relative power of the beta wave in the C3 area was statistically significantly increased (p<0.05). Conclusion: These findings suggest that 1AO and 3AO action observations are relevant to modifications of specific brain wave coherence and ERD values. EEG cortical activity during action observation may contribute to neural reorganization and to adaptive neuroplasticity in clinical intervention.