School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100080, China; Beijing Key Laboratory of Epilepsy, Epilepsy Center, Department of Functional Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, 100093, China.
School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, 100080, China.
Hear Res. 2018 Aug;365:165-173. doi: 10.1016/j.heares.2018.05.015. Epub 2018 May 23.
Central processing of interaural correlation (IAC), which depends on the precise representation of acoustic signals from the two ears, is essential for both localization and recognition of auditory objects. A complex soundwave is initially filtered by the peripheral auditory system into multiple narrowband waves, which are further decomposed into two functionally distinctive components: the quickly-varying temporal-fine structure (TFS) and the slowly-varying envelope. In rats, a narrowband noise can evoke auditory-midbrain frequency-following responses (FFRs) that contain both the TFS component (FFR) and the envelope component (FFR), which represent the TFS and envelope of the narrowband noise, respectively. These two components are different in sensitivity to the interaural time disparity. In human listeners, the present study investigated whether the FFR and FFR components of brainstem FFRs to a narrowband noise are different in sensitivity to IAC and whether there are potential brainstem mechanisms underlying the integration of the two components. The results showed that although both the amplitude of FFR and that of FFR were significantly affected by shifts of IAC between 1 and 0, the stimulus-to-response correlation for FFR, but not that for FFR, was sensitive to the IAC shifts. Moreover, in addition to the correlation between the binaurally evoked FFR and FFR, the correlation between the IAC-shift-induced change of FFR and that of FFR was significant. Thus, the TFS information is more precisely represented in the human auditory brainstem than the envelope information, and the correlation between FFR and FFR for the same narrowband noise suggest a brainstem binding mechanism underlying the perceptual integration of the TFS and envelope signals.
中枢对两耳间相关信息（IAC）的处理，依赖于对来自双耳的精确声学信号的表示，这对于听觉对象的定位和识别都是至关重要的。初始时，一个复杂的声波被外周听觉系统过滤成多个窄带波，这些窄带波进一步分解为两个功能上不同的成分：快速变化的时频精细结构（TFS）和缓慢变化的包络。在大鼠中，窄带噪声可以引起听觉中脑频率跟随反应（FFR），其中包含 TFS 成分（FFR）和包络成分（FFR），它们分别代表窄带噪声的 TFS 和包络。这两个成分对两耳时间差的敏感程度不同。在人类听众中，本研究探讨了窄带噪声脑干 FFR 的 FFR 和 FFR 成分对 IAC 的敏感性是否不同，以及是否存在潜在的脑干机制来整合这两个成分。结果表明，尽管 FFR 的振幅和 FFR 的振幅都受到 IAC 在 1 到 0 之间的变化的显著影响，但 FFR 的刺激-反应相关性，而不是 FFR 的，对 IAC 的变化敏感。此外，除了两耳诱发的 FFR 和 FFR 之间的相关性外，FFR 的 IAC 移位诱导变化与 FFR 的相关性也很显著。因此，与包络信息相比，TFS 信息在人类听觉脑干中得到了更精确的表示，并且相同窄带噪声的 FFR 和 FFR 之间的相关性表明了一种潜在的脑干绑定机制，用于整合 TFS 和包络信号的感知。
