Directional response properties of saccular afferents of the toadfish, Opsanus tau
Directional response properties of saccular afferents of the toadfish, Opsanus tau
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DOI：
10.1016/s0378-5955(97)00083-x
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发表时间：
1997-09-01
期刊：
影响因子：
2.8
通讯作者：
EddsWalton, PL
中科院分区：
文献类型：
--
作者：
Fay, RR;EddsWalton, PL
位移灵敏度，频率响应，和方向响应特性的初级囊状传入蟾鱼（Opsanus tau）进行了研究，响应模拟的声粒子运动的位移幅度和方向操纵的方位角和仰角。刺激为50、100和200 Hz的正弦曲线，在水平和正中矢状面的各个轴上对动物进行振荡。这些平面中的顶点在球坐标中定义了细胞的特征轴（具有最低阈值的轴）。记录来自囊神经的头侧、中间和尾侧束的传入。最敏感的囊状传入响应与锁相响应位移小至0.1 nm。这种敏感性与哺乳动物耳蜗的敏感性相媲美，可能是大多数鱼类的球囊和其他耳石器官所共有的。大多数传入神经在100 Hz时的阈值低于50或200 Hz。80%的传入神经具有三维方向性，如果它们支配囊状上皮上具有相同方向性取向的一组毛细胞，则预期具有三维方向性。在不完全定向的传入神经中，大多数似乎只支配两组具有不同方向的毛细胞。传入纤维的方向特性与球囊上毛细胞取向的解剖学定义模式定性相关。一般来说，最佳灵敏度的方位角倾向于平行于耳石和感觉上皮的平面。最佳灵敏度的升高与囊状上皮不同区域中的毛细胞取向模式很好地对应。在水平面上的方向性听力可能取决于对耳间差异的处理。这些反应的差异产生的总方向的球囊，并表示，在一定程度上，作为非自发传入，显示水平依赖的相位角同步之间的时间差。在垂直平面中的定向听觉可以来自于每个球囊内的活动的横向传入轮廓的处理。鱼类可能是最早解决声源定位问题的脊椎动物，我们认为它们的解决方案为它们的陆地继承者提供了一个模型。
The displacement sensitivity, frequency response, and directional response properties of primary saccular afferents of toadfish (Opsanus tau) were studied in response to a simulation of acoustic particle motion for which displacement magnitudes and directions were manipulated in azimuth and elevation. Stimuli were 50, 100, and 200 Hz sinusoidal, translatory oscillations of the animal at various axes in the horizontal and midsagittal planes. Thresholds in these planes defined a cell's characteristic axis (the axis having the lowest threshold) in spherical coordinates. Recordings were made from afferents in rostral, middle, and caudal bundles of the saccular nerve. The most sensitive saccular afferents responded with a phase-locked response to displacements as small as 0.1 nm. This sensitivity rivals that of the mammalian cochlea and is probably common to the sacculi and other otolith organs of most fishes. Most afferents showed lower thresholds at 100 Hz than at 50 or 200 Hz. Eighty percent of afferents have three-dimensional directional properties that would be expected if they innervated a group of hair cells having the same directional orientation on the saccular epithelium. Of the afferents that are not perfectly directional, most appear to innervate just two groups of hair cells having different orientations. The directional characteristics of afferents are qualitatively correlated with anatomically defined patterns of hair cell orientation on the saccule. In general, azimuths of best sensitivity tend to lie parallel to the plane of the otolith and sensory epithelium. Elevations of best sensitivity correspond well with hair cell orientation patterns in different regions of the saccular epithelium. Directional hearing in the horizontal plane probably depends upon the processing of interaural differences in overall response magnitude. These response differences arise from the gross orientations of the sacculi and are represented, in part, as time differences among nonspontaneous afferents that show level-dependent phase angles of synchronization. Directional hearing in the vertical plane may be derived from the processing of across-afferent profiles of activity within each saccule. Fishes were probably the first vertebrates to solve problems in sound source localization, and we suggest that their solutions formed a model for those of their terrestrial inheritors.