Spike recorded by multi-channel microelectrode array is very weak and susceptible to interference, whose noisy characteristic affects the accuracy of spike detection. Aiming at the independent white noise, correlation noise and colored noise in the process of spike detection, combining principal component analysis (PCA), wavelet analysis and adaptive time-frequency analysis, a new denoising method (PCWE) that combines PCA-wavelet (PCAW) and ensemble empirical mode decomposition is proposed. Firstly, the principal component was extracted and removed as correlation noise using PCA. Then the wavelet-threshold method was used to remove the independent white noise. Finally, EEMD was used to decompose the noise into the intrinsic modal function of each layer and remove the colored noise. The simulation results showed that PCWE can increase the signal-to-noise ratio by about 2.67 dB and decrease the standard deviation by about 0.4 μV, which apparently improved the accuracy of spike detection. The results of measured data showed that PCWE can increase the signal-to-noise ratio by about 1.33 dB and reduce the standard deviation by about 18.33 μV, which showed its good denoising performance. The results of this study suggests that PCWE can improve the reliability of spike signal and provide an accurate and effective spike denoising new method for the encoding and decoding of neural signal.
多通道微电极阵列记录的锋电位（Spike）十分微弱，极易受干扰，其含噪的特性影响了 Spike 检出的准确率。针对 Spike 检测过程中通常存在的独立白噪声、相关噪声与有色噪声，本文结合主成分分析（PCA）、小波分析和自适应时频分析，提出 PCA-小波（PCAW）与整体平均经验模态分解（EEMD）联合的去噪新方法（PCWE）。首先，利用 PCA 提取多通道神经信号通道间的主成分作为相关噪声去除；然后利用小波阈值法对独立白噪声进行去除；最后利用 EEMD 把噪声分解到各层本质模态函数中，对有色噪声进行去除。仿真结果表明，PCWE 使信噪比约提高 2.67 dB，标准差约减小 0.4 μV，显著提高了 Spike 的检出精确率；实测数据结果表明，PCWE 能使信噪比约提高 1.33 dB，标准差约减小 18.33 μV，表现出良好的去噪性能。本文研究结果表明，PCWE 可以提高 Spike 信号的可靠性，或可为神经信号的编码解码提供一种新型有效的锋电位去噪方法。.
Keywords: ensemble empirical mode decomposition; principal component analysis; signal-to-noise ratio; spike; wavelet-threshold denoising.