Institute of Medical Psychology, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Heinrich-Hoffmann-Strasse 10, D-60528 Frankfurt am Main, Germany.
J Neurophysiol. 2012 Apr;107(7):1962-9. doi: 10.1152/jn.00418.2011. Epub 2012 Jan 18.
Contralateral acoustic stimulation (CAS) with white noise and pure tone stimuli was used to assess frequency specificity of efferent olivocochlear control of cochlear mechanics in the gerbil. Changes of the cochlear amplifier can be monitored by distortion product otoacoustic emissions (DPOAEs), which are a byproduct of the nonlinear amplification by the outer hair cells. We used the quadratic DPOAE f2-f1 as ipsilateral probe, as it is known to be sensitive to efferent olivocochlear activity. White noise CAS, used to evoke efferent activity, had maximal effects on the DPOAE level for f2-stimulus frequencies of 5-7 kHz. The dominant effect during CAS was a DPOAE level increase of up to 13.5 dB. The frequency specificity of the olivocochlear system was evaluated by presenting pure tones (0.5-38 kHz) as contralateral stimuli to evoke efferent activity. Maximal DPOAE level changes were triggered by CAS frequencies close to the frequency of the DPOAE elicitor tones (tested f2 range: 2.5-15 kHz). The effective CAS frequency range covered 1.4-2.4 octaves and was centered 0.42 octaves below the DPOAE elicitor tone f2. The frequency-specific effect of CAS with pure tones suggests a dedicated central control of mechanical adjustments for peripheral frequency processing.
采用白噪声和纯音对侧声刺激（CAS）来评估外侧橄榄耳蜗控制耳蜗力学的传出活动的频率特异性。通过畸变产物耳声发射（DPOAE）可以监测耳蜗放大器的变化，这是外毛细胞非线性放大的副产品。我们使用二次 DPOAE f2-f1 作为同侧探针，因为它已知对传出橄榄耳蜗活动敏感。用于诱发传出活动的白噪声 CAS 对 5-7 kHz 的 f2 刺激频率的 DPOAE 水平具有最大的影响。在 CAS 期间，主要的影响是 DPOAE 水平增加了高达 13.5 dB。通过将纯音（0.5-38 kHz）作为对侧刺激来诱发传出活动，评估了橄榄耳蜗系统的频率特异性。最大的 DPOAE 水平变化是由接近 DPOAE 激发音频率的 CAS 频率触发的（测试的 f2 范围：2.5-15 kHz）。有效的 CAS 频率范围覆盖了 1.4-2.4 个倍频程，中心位于 DPOAE 激发音 f2 下方 0.42 个倍频程。纯音对侧声刺激的频率特异性效应表明，对周围频率处理的机械调整有专门的中央控制。
