Müller M
Zoological Institute, J.W. Goethe-University, Frankfurt, Federal Republic of Germany.
Exp Brain Res. 1990;81(1):140-9. doi: 10.1007/BF00230110.
Frequency representation in the auditory brainstem nuclei of the fattailed gerbil (Pachyuromys duprasi) was studied by focal iontophoretic HRP injections into the cochlear nucleus at physiologically characterized positions. Tuning curves of cochlear nucleus neurons were determined by extracellular recording of multi-unit spike activity prior to HRP application. Neurons with characteristic frequencies of 0.55 to 17.5 kHz were recorded. Anterograde labeling of synaptic terminal fields demonstrated a tonotopic arrangement of frequencies within the cochlear nucleus subdivisions and the lateral and medial superior olivary nuclei. In all nuclei investigated terminal fields were arranged in isofrequency planes. In the subdivisions of the cochlear nucleus and in the lateral superior olive the frequency range from 0.55 to 17.5 kHz was represented. In the medial superior olive on the other hand, frequency representation was restricted to frequencies below 3.5 kHz. Quantitative evaluation of tonotopy showed that the frequency representation in the anteroventral and posteroventral cochlear nucleus and lateral superior olive were very similar. The amount of tissue-volume processing one octave varied within the hearing range. The frequency range of highest auditory sensitivity (between 1 and 5 kHz) occupied up to 25% nuclear tissue/octave, while at the upper and lower limits of the hearing range, frequencies were represented by a ratio of 10-15% nuclear tissue/octave. The frequency representation pattern in these brainstem nuclei reflected exactly the frequency place map of the cochlea.
通过将辣根过氧化物酶（HRP）离子电渗法局部注射到肥尾沙鼠（Pachyuromys duprasi）耳蜗核中生理特征明确的位置，研究了其听觉脑干核中的频率表征。在应用HRP之前，通过细胞外记录多单位锋电位活动来确定耳蜗核神经元的调谐曲线。记录到特征频率为0.55至17.5 kHz的神经元。突触终末场的顺行标记显示，在耳蜗核亚区以及外侧和内侧上橄榄核内频率呈音频拓扑排列。在所研究的所有核中，终末场均排列在等频率平面上。在耳蜗核亚区和外侧上橄榄核中，呈现了0.55至17.5 kHz的频率范围。另一方面，在内侧上橄榄核中，频率表征仅限于低于3.5 kHz的频率。对音频拓扑的定量评估表明，前腹侧和后腹侧耳蜗核以及外侧上橄榄核中的频率表征非常相似。在听力范围内，处理一个倍频程的组织体积量有所不同。最高听觉敏感度的频率范围（1至5 kHz之间）占据高达25%的核组织/倍频程，而在听力范围的上限和下限处，频率由10 - 15%的核组织/倍频程比例表示。这些脑干核中的频率表征模式准确反映了耳蜗的频率位置图。
