Salt A N, Garcia P
Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri 63110.
J Acoust Soc Am. 1990 Sep;88(3):1392-402. doi: 10.1121/1.399717.
Previous action potential (AP) tuning curve methods have used a reduction in amplitude of the probe-elicited AP as an indication of tone-induced masking. The reduction criterion used in different studies has varied from 25% to 100%. For low level probe stimuli, which elicit a low-amplitude AP, this is a sensitive indicator. In contrast, for high-amplitude AP responses elicited by high-level stimuli, the required reduction in absolute terms is large, making it an insensitive indicator. AP tuning curves have been recorded using a sensitive method for detecting masker/probe interaction with a fixed criterion, unrelated to the unmasked AP amplitude. For each masking condition, a derived response was obtained by digitally subtracting the tone-masked AP waveform from the unmasked response. Derived responses are generated if there are ANY changes in the AP waveform induced by the masker, including amplitude changes, latency changes, or even changes in AP morphology not necessarily associated with the major peaks. A fixed criterion (10 microV) of tone-derived (TD) response was used as an indication of interaction of the responses to the masker and probe. Tuning curves generated by this method were compared with those generated by conventional amplitude reduction (AR) methods. TD tuning curves show different characteristics, especially with respect to increasing probe levels. They appear to give a good representation of the array of afferent fibers responding to a probe stimulus. In addition, frequency regions making minor contributions to the AP are better represented in TD tuning curves.
以往的动作电位（AP）调谐曲线方法使用探头诱发的AP幅度降低作为音调诱发掩蔽的指标。不同研究中使用的降低标准从25%到100%不等。对于低水平的探头刺激，其诱发的AP幅度较低，这是一个敏感指标。相比之下，对于高水平刺激诱发的高幅度AP反应，绝对值所需的降低幅度很大，使其成为一个不敏感指标。AP调谐曲线是使用一种灵敏的方法记录的，该方法用于检测掩蔽器/探头相互作用，采用与未掩蔽AP幅度无关的固定标准。对于每种掩蔽条件，通过从非掩蔽反应中数字减去音调掩蔽的AP波形来获得派生反应。如果掩蔽器诱发AP波形有任何变化，包括幅度变化、潜伏期变化，甚至与主峰不一定相关的AP形态变化，都会产生派生反应。音调派生（TD）反应的固定标准（10微伏）被用作掩蔽器和探头反应相互作用的指标。将该方法生成的调谐曲线与传统幅度降低（AR）方法生成的调谐曲线进行比较。TD调谐曲线显示出不同的特征，特别是在探头水平增加方面。它们似乎很好地表示了对探头刺激作出反应的传入纤维阵列。此外，对AP贡献较小的频率区域在TD调谐曲线中得到了更好的表示。
