Firszt Jill B, Chambers And Ron D, Kraus Nina
Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee 53226, USA.
Ear Hear. 2002 Dec;23(6):516-31. doi: 10.1097/00003446-200212000-00003.
The overall objective of this study was to relate electrically evoked potentials recorded from different levels of the auditory pathway with behavioral measures obtained from adult cochlear implant subjects. The hypothesis was that adult recipients of cochlear implants who have open-set speech perception and those recipients with no open-set speech perception would differ in their neurophysiologic responses recorded at one or more levels of the auditory pathway.
The subjects were 11 adults implanted with the Clarion cochlear implant. The electrical auditory brainstem response (EABR, Wave V), electrical auditory middle latency response (EAMLR, Na-Pa complex), and the electrical late auditory response (ELAR, N1-P2 complex), were recorded from three intra-cochlear electrodes. The stimuli used to record the evoked potentials varied in rate and amplitude. Behavioral measures (between threshold and upper limit of comfortable loudness) were used to define the subject's dynamic range at the different stimulus rates. Word and sentence recognition tests evaluated subjects' speech perception in quiet and noise. Evoked potential and behavioral measures were examined for statistical significance using analysis of variance for repeated measures and correlational analyses.
Subjects without open-set speech recognition demonstrated 1) poorly formed or absent evoked potential responses, 2) reduced behavioral dynamic ranges, 3) lack of change in the size of the dynamic range with a change in stimulus rate, and 4) longer periods of auditory deprivation. The variables that differentiated the best performers included 1) presence of responses at all three levels of the auditory pathway, with large normalized amplitudes for the EAMLR, 2) lower evoked potential thresholds for the Na-Pa complex, 3) relatively large dynamic ranges, and 4) changes in the size of the dynamic range with changes in stimulus rate.
In this study, the inability to follow changes in the temporal characteristics of the stimulus was associated with poor speech perception performance. Results also illustrate that variability in speech perception scores of cochlear implant recipients relates to neurophysiologic responses at higher cortical levels of the auditory pathway. Presumably, limited neural synchrony for elicitation of electrophysiologic responses underlies limited speech perception. Results confirm that neural encoding with electrical stimulation must provide sufficient physiologic responses of the central nervous system to perceive speech through a cochlear implant.
本研究的总体目标是将从听觉通路不同水平记录的电诱发电位与成年人工耳蜗受试者的行为测量结果相关联。假设是，具有开放式言语感知能力的成年人工耳蜗接受者与没有开放式言语感知能力的接受者在听觉通路一个或多个水平记录的神经生理反应上会有所不同。
受试者为11名植入Clarion人工耳蜗的成年人。从三个耳蜗内电极记录电听觉脑干反应（EABR，波V）、电听觉中潜伏期反应（EAMLR，Na-Pa复合波）和电听觉晚期反应（ELAR，N1-P2复合波）。用于记录诱发电位的刺激在速率和幅度上有所不同。行为测量（在阈值和舒适响度上限之间）用于定义受试者在不同刺激速率下的动态范围。单词和句子识别测试评估受试者在安静和噪声环境中的言语感知能力。使用重复测量方差分析和相关分析检查诱发电位和行为测量的统计学意义。
没有开放式言语识别能力的受试者表现出：1）诱发电位反应波形不佳或缺失；2）行为动态范围减小；3）动态范围大小不随刺激速率变化；4）听觉剥夺时间更长。区分表现最佳者的变量包括：1）在听觉通路所有三个水平均有反应，EAMLR的归一化幅度较大；2）Na-Pa复合波的诱发电位阈值较低；3）相对较大的动态范围；4）动态范围大小随刺激速率变化。
在本研究中，无法跟随刺激时间特征的变化与言语感知表现不佳相关。结果还表明，人工耳蜗接受者言语感知分数的变异性与听觉通路较高皮层水平的神经生理反应有关。据推测，电生理反应诱发的神经同步性有限是言语感知受限的基础。结果证实，电刺激的神经编码必须为中枢神经系统提供足够的生理反应，以便通过人工耳蜗感知言语。
