Möckel Doreen, Seyfarth Ernst-August, Kössl Manfred
Institut für Zellbiologie und Neurowissenschaft, J. W. Goethe-Universität, Siesmayerstrasse 70, Biologie Campus, Haus A, 60323 Frankfurt am Main, Germany.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2007 Aug;193(8):871-9. doi: 10.1007/s00359-007-0239-5. Epub 2007 May 30.
Tympanal organs of insects emit distortion-product otoacoustic emissions (DPOAEs) that are indicative of nonlinear ear mechanics. Our study sought (1) to define constraints of DPOAE generation in the ear of Locusta migratoria, and (2) to identify the sensory structures involved. We selectively destroyed the connection between the (peripheral) sensory ganglion and the tympanal attachment points of the "d-cell" dendrites; d-cells are most sensitive to sound frequencies above 12 kHz. This led to a decrease of DPOAEs that were evoked by f (2) frequencies above 15 kHz (decrease of 15-40 dB; mean 28 dB; n = 12 organs). DPOAEs elicited by lower frequencies remained unchanged. Such frequency-specific changes following the exclusion of one scolopidial sub-population suggest that these auditory scolopidia are in fact the source of DPOAEs in insects. Electrical stimulation of the auditory nerve (with short current pulses of 4-10 microA or DC-currents of 0.5 microA) reversibly reduced DPOAEs by as much as 30 dB. We assume that retrograde electrical stimulation primarily affected the neuronal part of the scolopidia. Severing the auditory nerve from the central nervous system (CNS) did not alter the DPOAE amplitudes nor the effects of electrical stimulation.
昆虫的鼓膜器官会发出畸变产物耳声发射（DPOAE），这表明了耳朵的非线性力学特性。我们的研究旨在：（1）确定飞蝗耳朵中DPOAE产生的限制因素；（2）识别其中涉及的感觉结构。我们选择性地破坏了（外周）感觉神经节与“d细胞”树突的鼓膜附着点之间的连接；d细胞对高于12kHz的声音频率最为敏感。这导致由高于15kHz的f（2）频率诱发的DPOAE有所降低（降低了15 - 40dB；平均28dB；n = 12个器官）。由较低频率诱发的DPOAE保持不变。在排除一个 scolopidial 亚群后出现的这种频率特异性变化表明，这些听觉 scolopidia 实际上是昆虫中DPOAE的来源。对听神经进行电刺激（使用4 - 10微安的短电流脉冲或0.5微安的直流电流）可使DPOAE可逆地降低多达30dB。我们假设逆行电刺激主要影响了 scolopidia 的神经元部分。切断听神经与中枢神经系统（CNS）的连接既没有改变DPOAE的幅度，也没有改变电刺激的效果。
