Tonotopic tuning in a sound localization circuit.
Tonotopic tuning in a sound localization circuit.
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声音定位电路中的音调调谐。
DOI：
10.1152/jn.00678.2009
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发表时间：
2010
影响因子：
2.5
通讯作者：
Spain,WilliamJ
中科院分区：
文献类型：
--
作者：
Slee,SeanJ;Higgs,MatthewH;Fairhall,AdrienneL;Spain,WilliamJ
层状核（NL）神经元编码耳间时差（ITD），这是一种用于定位低频声音的线索。基于生理的NL输入模型表明，过渡段信息包含在声音频率谐波周围的窄频带中。这提出了一个理论，该理论预测，对于每个音调频率，突触输入到NL的最佳时间过程将引起NL放电率作为ITD的函数的最大调制。该理论还表明，NL不同张力区域的神经元需要专门的调谐来利用输入梯度。在脑切片上，根据核的解剖张力图将核分成三个区域，研究了核的张力调整。每个区域的膜片钳记录被用来测量突触和固有的电特性。数据显示突触时间过程的张力梯度与理论预测非常吻合。我们还发现了突触后带通滤波。结合突触和突触后滤波器的分析揭示了音调振幅到NL发射速率调制的转换增益的频率依赖性梯度。根据实验数据构建的模型表明，在NL中测量的音调调谐可以改善跨声音频率的过渡段编码。
Nucleus laminaris (NL) neurons encode interaural time difference (ITD), the cue used to localize low-frequency sounds. A physiologically based model of NL input suggests that ITD information is contained in narrow frequency bands around harmonics of the sound frequency. This suggested a theory, which predicts that, for each tone frequency, there is an optimal time course for synaptic inputs to NL that will elicit the largest modulation of NL firing rate as a function of ITD. The theory also suggested that neurons in different tonotopic regions of NL require specialized tuning to take advantage of the input gradient. Tonotopic tuning in NL was investigated in brain slices by separating the nucleus into three regions based on its anatomical tonotopic map. Patch-clamp recordings in each region were used to measure both the synaptic and the intrinsic electrical properties. The data revealed a tonotopic gradient of synaptic time course that closely matched the theoretical predictions. We also found postsynaptic band-pass filtering. Analysis of the combined synaptic and postsynaptic filters revealed a frequency-dependent gradient of gain for the transformation of tone amplitude to NL firing rate modulation. Models constructed from the experimental data for each tonotopic region demonstrate that the tonotopic tuning measured in NL can improve ITD encoding across sound frequencies.