Patuzzi R
Physiology Department, University of Western Australia, Nedlands, Australia.
Hear Res. 1998 Nov;125(1-2):39-70. doi: 10.1016/s0378-5955(98)00127-0.
A model of the temporary threshold shift (TTS) following loud sound is presented based on inactivation of the mechano-electrical transduction (MET) channels at the apex of the outer hair cells (OHCs). This inactivation is assumed to reduce temporarily the OHC receptor current with a consequent drop in the mechanical sensitivity of the organ of Corti. With acoustic over-stimulation some of the hair cells' MET channels are assumed to adopt one of three closed and non-transducing conformations or 'TTS states'. The sound-induced inactivation is assumed to occur because the sound makes the TTS states more energetically favourable when compared with the transducing states, and the distribution between these states is assumed to depend on the relative energies of the states and the time allowed for migration between them. By lumping the fast transducing states (one open and two closed) into a single transducing 'pseudo-state', the kinetics of the inactivation and re-activation processes (corresponding to the onset and recovery of TTS) can be described by a four-state kinetic model. The model allows an elegant description of the onset and recovery of TTS time-course in a human subject under a variety of continuous exposure conditions, and some features of intermittent exposure as well. The model also suggests that recovery of TTS may be accelerated by an intermittent tone during the recovery period which may explain some variability TTS in the literature. Other implications of the model are also discussed.
基于外毛细胞（OHC）顶端机械电转导（MET）通道的失活，提出了一种强声后暂时性阈移（TTS）的模型。这种失活被认为会暂时降低OHC受体电流，从而导致柯蒂氏器的机械敏感性下降。在声学过度刺激下，一些毛细胞的MET通道被认为会采用三种关闭且不进行转导的构象或“TTS状态”之一。声音诱导的失活被认为是因为与转导状态相比，声音使TTS状态在能量上更有利，并且这些状态之间的分布被认为取决于状态的相对能量以及它们之间迁移所允许的时间。通过将快速转导状态（一个开放和两个关闭）归为一个单一的转导“伪状态”，失活和重新激活过程（对应于TTS的起始和恢复）的动力学可以用一个四态动力学模型来描述。该模型能够很好地描述在各种连续暴露条件下人类受试者中TTS时间进程的起始和恢复，以及间歇性暴露的一些特征。该模型还表明，在恢复期间，间歇性音调可能会加速TTS的恢复，这可能解释了文献中TTS的一些变异性。还讨论了该模型的其他含义。
