最大长度序列诱发听性脑干反应的线性与非线性成分引出率和稳定性分析

在记录常规的听性脑干反应(cABR)时，听觉系统被视为一个线性系统，无法获取反映听觉系统非线性特性的成分。而采用最大长度序列(MLS)刺激，对记录的反应建立Volterra级数展开模型，能够同时获取反映听觉系统线性与非线性特性的不同成分，所获取的ABR被称为MLS-ABR。由于这种方法在实验和计算方面的困难，现阶段对MLS-ABR的特性了解尚少，所以通过实验研究对其引出率及稳定性进行分析。利用MLS方法提取非线性成分，选择一个9阶MLS，提取11例正常青年人的MLS-ABR及cABR，其中MLS-ABR的一阶和一个二阶核切片（VS1和VS21）的波形清晰完整，分别表达ABR的线性和非线性成分。以cABR、VS1、VS21中各特征波出现率、潜伏期及峰峰值变异系数为考察指标，对照分析cABR与MLS ABR的线性、非线性成分引出率和稳定性。结果发现，MLS-ABR中线性成分各特征波引出率都较高（>90%），且其潜伏期（1、3、5潜伏期波变异系数分别为5.17、3.70、2.00）比cABR（Ⅰ、Ⅲ、Ⅴ波潜伏期变异系数分别为6.54、3.70、2.87）更加稳定；非线性成分也可稳定引出1、3、5波（>80%），并且非线性成分的在5波的表达更加强烈。进一步证实MLS在获取ABR非线性成分的可靠性，加深对MLR-ABR的认识，为后续相关研究提供重要依据。

Analysis on Elicitation and Stability of Linear and Nonlinear Components in Maximum Length Sequence Evoked Auditory Brainstem Response

The auditory system is treated as a linear system to record the conventional auditory brainstem response (cABR). An advanced stimulation technique using maximum length sequence (MLS) is introduced to establish a Volterra series expansion model, and to obtain the representation of ABR components in response to individual and multiple stimulation. Under this way, the ABR is called MLS-ABR. To date, the literature report on nonlinear MLS-ABR has been limited due to the acquisition and technique difficulty. This study was aiming to investigate nonlinear ABRs using a MLS stimulation of 9^th degree on 11 normal human adults. The MLS-ABR featured waves 1, 3, and 5, corresponding to cABR, waves I, II and V were selected for further analysis. The results demonstrated a clear morphology of the first order and second order kernel slices (VS1 and VS21), which reflect the linear and nonlinear components of ABR, with relative high elicitations (> 80 %) of the selected featured waves for both slices, and particularly, the wave 5 exhibited strong nonlinear effects. The variable coefficients were used to quantify the latency stability of the featured waves in comparison with that of cABRs. The results presented that the linear components in MLS ABR (the variable coefficients of wave 1, 3, 5 were 5.17, 3.70, 2.00, respectively) was more stable than cABR (the variable coefficients of wave I, III, V were 6.54, 3.70, 2.87), This study validated that nonlinearity of ABR could be presented by MLS method, and demonstrated the fundamental nonlinear characteristics of MLS ABRs, providing a reference for future study.