OLIVOCOCHLEAR EFFERENT SYSTEMS

内侧橄榄耳蜗传出系统几乎普遍存在于 哺乳动物的听觉系统，然而它的作用机制和它的 功能意义仍不清楚。我们之前的工作表明 在低声级和高声级观察到的传出抑制可能具有 完全不同的生理基础，前者通过外毛- 细胞突触电导分流OHC受体电流，后者 通过对内毛细胞和传入神经元的电效应。一个 分析这些低声级和高声级机制的含义， 我们的初步结果表明，目前对这种模式的看法 传出效果随声音频率、声级、传出效果的变化 射速和射出的次数基本上是 不正确。拟议的实验工作将检验具体的假设， 根据我们过去的工作，关于传出抑制的机制 无论是在低音量还是在高音量下。所获得的数据将 生成一张新的、更复杂的关于放电模式如何 听神经纤维受到不同程度的传出活动的影响。 这些数据将使我们能够预测来自耳朵的感觉输入是如何 在许多不同的条件下进行修改，以使功能结果 可以推论。这一知识应该有助于理解两个正常的 和病理性听力，并增加了对反馈的日益理解 神经生物学中的控制系统。

The medial olivocochlear efferent system is almost universally present in mammalian auditory systems, yet the mechanisms by which it acts and its functional significance are still unclear. Our previous work suggests that efferent inhibition observed at low and high sound levels may have entirely different physiological bases, the former through the outer-hair- cell (OHC) synaptic conductance shunting OHC receptor currents, the latter through electrical effects on inner hair cells and afferent neurons. An analysis of the implications of these low and high sound level mechanisms, and our preliminary results, indicate that current views about the pattern of efferent effects with changes in sound frequency, sound level, efferent firing rate, and the number of efferents firing are fundamentally incorrect. The proposed experimental work will test specific hypotheses, formulated from our past work, about the mechanisms of efferent inhibition both at low sound levels and at high sound levels. The data obtained will generate a new and more complex picture of how discharge patterns in auditory nerve fibers are affected by various levels of efferent activity. These data will enable us to predict how sensory input from the ear is modified under many different conditions so that functional consequences can be deduced. This knowledge should aid in understanding both normal and pathological hearing and add to the growing understanding of feedback control systems in neurobiology.