Moser Tobias, Neef Andreas, Khimich Darina
Department of Otolaryngology, Göttingen University Medical School, Robert-Koch-Strasse 40, 37075 Göttingen, Germany.
J Physiol. 2006 Oct 1;576(Pt 1):55-62. doi: 10.1113/jphysiol.2006.114835. Epub 2006 Aug 10.
Our auditory system is capable of perceiving the azimuthal location of a low frequency sound source with a precision of a few degrees. This requires the auditory system to detect time differences in sound arrival between the two ears down to tens of microseconds. The detection of these interaural time differences relies on network computation by auditory brainstem neurons sharpening the temporal precision of the afferent signals. Nevertheless, the system requires the hair cell synapse to encode sound with the highest possible temporal acuity. In mammals, each auditory nerve fibre receives input from only one inner hair cell (IHC) synapse. Hence, this single synapse determines the temporal precision of the fibre. As if this was not enough of a challenge, the auditory system is also capable of maintaining such high temporal fidelity with acoustic signals that vary greatly in their intensity. Recent research has started to uncover the cellular basis of sound coding. Functional and structural descriptions of synaptic vesicle pools and estimates for the number of Ca(2+) channels at the ribbon synapse have been obtained, as have insights into how the receptor potential couples to the release of synaptic vesicles. Here, we review current concepts about the mechanisms that control the timing of transmitter release in inner hair cells of the cochlea.
我们的听觉系统能够精确到几度来感知低频声源的方位位置。这就要求听觉系统检测两耳之间声音到达的时间差异，精确到几十微秒。这些双耳时间差异的检测依赖于听觉脑干神经元的网络计算，以提高传入信号的时间精度。然而，该系统要求毛细胞突触以尽可能高的时间敏锐度对声音进行编码。在哺乳动物中，每根听神经纤维仅从一个内毛细胞（IHC）突触接收输入。因此，这个单一突触决定了纤维的时间精度。似乎这还不够具有挑战性，听觉系统还能够对强度变化很大的声学信号保持如此高的时间保真度。最近的研究已经开始揭示声音编码的细胞基础。已经获得了突触小泡池的功能和结构描述以及对带状突触处Ca(2+)通道数量的估计，同时也深入了解了受体电位如何与突触小泡的释放相耦合。在这里，我们回顾了当前关于控制耳蜗内毛细胞递质释放时间机制的概念。
