手抓握时大脑皮层与上肢肌肉间信息传输的研究

项目名称： 手抓握时大脑皮层与上肢肌肉间信息传输的研究

项目编号： No.81071231

项目类型： 面上项目

立项/批准年度： 2011

项目学科： 无线电电子学、电信技术

项目作者： 郝冬梅

作者单位： 北京工业大学

项目金额： 10万元

中文摘要： 大脑皮层通过脊髓和周围神经控制肌肉组织，使得肢体可以完成一定的运动功能，大脑运动皮层与肌肉间的信息传递是通过运动神经互相连接实现的，二者间的功能连接即为皮层-肌肉功能耦合，它是揭示运动障碍的重要指标。1）课题设计了表面肌电和握力信号的同步检测电路， 利用LABVIEW虚拟仪器对信号采集和分析。记录了10名健康被试者在不同输出力以及连续最大握力后疲劳状态下指伸肌、尺侧腕伸肌和桡侧腕短伸肌的表面肌电信号，计算了在不同力输出状态下表面肌电信号的均方根、平均功率频率和中位频率。结果显示：均方根随着主动输出力的增大而增大，增大输出力需要招募更多的运动单元或者运动单元的兴奋性增强以维持力的输出；在疲劳状态下，输出力下降但是均方根增大，运动单元的放电频率下降，导致平均功率频率和中位频率向低频段移动。2）设计了基于小波包能量分析的肌肉疲劳识别方法，能较客观地判断肌肉疲劳。3）设计了手抓握实验，同步记录脑电、肌电和输出力信号，计算对侧大脑运动皮层和肱桡肌间的相干性，发现在疲劳状态下，皮层-肌肉相干值在θβ#947;频带较大，而在α39057;带较低。在正常力输出下α39057;带相干值较高，皮层-肌肉间的联系较强。

中文关键词： 脑电；肌电；皮层-肌肉相干；因果性；

英文摘要： Voluntary movement is a result of the cortical command driving muscle action through spinal cord and peripheral nerve. Spectral coherence of electroencephalographic (EEG) overlying primary motor cortex and electromyographic (EMG) data reflects functional corticomuscular coupling between cortex and motor units firing in the target muscle. EEG- EMG coherence would represent a rough index of information transfer capability within the operative connection and indicate the motor ability. A simultaneous measurement system of surface EMG (sEMG) and handgrip force was developed with EMG-Force amplifier and LabVIEW. Ten healthy subjects were required to perform a series of static contraction trials by maintaining the force level with maximal voluntary contraction (MVC), 75%MVC, 50%MVC and 25%MVC respectively. Then they were encouraged to continue the sustained MVC as long as possible until resulting fatigue. sEMG signals were recorded on three forearm muscles, that is extensor digitorum(ED), extensor carpi ulnaris (ECU) and extensor carpi radialis brevis (ECRB), and handgrip force was measured at the same time as well. Root mean square (RMS), mean power frequency (MPF) and median frequency (MF) of the sEMG during handgrip were calculated with LabVIEW function modules. The results showed the RMS increased with the force level to recruit more motor unit or increase neuron activity to maintain voluntary contraction, while the MPF and MF shifted to lower frequency during fatigue condition due to the decrease of motor unit firing. Further, muscle fatigue could be recognized based on wavelet packet energy transform and artificial neural network. In addition, other seven subjects performed a series of handgrip tasks while their EEG, sEMG and exerted force were recorded synchronously by electrodes and sensors. The coherence of electroencephalographic (EEG) over contralateral motor cortex and EMG over brachioradialis increased significantly at θβnd γand and decreased at αand with fatigue while the coherence was high at αand with MVC and 50%MVC. It concluded that cortex and motor units interdepend each other at αand normally while it was inhibited in fatigue state.

英文关键词： EEG; EMG; corticomuscular coherence; causality; fatigue