Weeg M S, Fay R R, Bass A H
Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2002 Sep;188(8):631-41. doi: 10.1007/s00359-002-0338-2. Epub 2002 Aug 21.
While particle motion is thought to directly stimulate the inner ear of most fish species, it is difficult to measure and might not be predictable from pressure measurements in a small tank. It is therefore important to replicate experiments conducted relative to pressure measurements using stimuli of known particle motion, to ensure that unmeasured components of the stimulus field do not produce misleading frequency response profiles. The frequency sensitivity of the inner ear of the plainfin midshipman fish, Porichthys notatus, in response to isopressure stimuli has been described. This study now examines the frequency and directional response properties of midshipman saccular afferents in response to whole-body displacements simulating acoustic particle motion. Best frequencies were distributed bimodally, with peaks at 50 Hz and 100 Hz. Most units had cosinusoidally shaped directional response profiles in the horizontal and vertical planes, though some units showed slight deviations from this pattern. A few units (probably saccular efferents) had omnidirectional directional response profiles and did not phase lock to the stimulus waveform. These results are consistent with responses of the midshipman saccular nerve to isopressure stimuli, and strengthen the hypothesis that the frequency sensitivity of the midshipman ear matches the frequency content of behaviorally relevant vocalizations.
虽然粒子运动被认为会直接刺激大多数鱼类的内耳，但在小型水箱中，粒子运动很难测量，而且通过压力测量也可能无法预测。因此，使用已知粒子运动的刺激来重复与压力测量相关的实验非常重要，以确保刺激场中未测量的成分不会产生误导性的频率响应曲线。已经描述了光鳍后肛鱼（Porichthys notatus）内耳对等压刺激的频率敏感性。本研究现在考察了后肛鱼球囊传入神经对模拟声学粒子运动的全身位移的频率和方向响应特性。最佳频率呈双峰分布，峰值分别在50赫兹和100赫兹。大多数单元在水平和垂直平面上具有余弦形状的方向响应曲线，不过一些单元与这种模式略有偏差。少数单元（可能是球囊传出神经）具有全向的方向响应曲线，并且不与刺激波形锁相。这些结果与后肛鱼球囊神经对等压刺激的响应一致，并强化了这样的假设，即后肛鱼内耳的频率敏感性与行为相关发声的频率成分相匹配。
