McColgan Thomas, Shah Sahil, Köppl Christine, Carr Catherine, Wagner Hermann
Institute for Biology II, Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen, Aachen, Germany; Institute for Theoretical Biology, Humboldt-Universität zu Berlin, Berlin, Germany;
Department of Biology, University of Maryland, College Park, Maryland;
J Neurophysiol. 2014 Dec 1;112(11):2850-64. doi: 10.1152/jn.00484.2014. Epub 2014 Sep 3.
Inputs from the two sides of the brain interact to create maps of interaural time difference (ITD) in the nucleus laminaris of birds. How inputs from each side are matched with high temporal precision in ITD-sensitive circuits is unknown, given the differences in input path lengths from each side. To understand this problem in birds, we modeled the geometry of the input axons and their corresponding conduction velocities and latencies. Consistent with existing physiological data, we assumed a common latency up to the border of nucleus laminaris. We analyzed two biological implementations of the model, the single ITD map in chickens and the multiple maps of ITD in barn owls. For binaural inputs, since ipsi- and contralateral initial common latencies were very similar, we could restrict adaptive regulation of conduction velocity to within the nucleus. Other model applications include the simultaneous derivation of multiple conduction velocities from one set of measurements and the demonstration that contours with the same ITD cannot be parallel to the border of nucleus laminaris in the owl. Physiological tests of the predictions of the model demonstrate its validity and robustness. This model may have relevance not only for auditory processing but also for other computational tasks that require adaptive regulation of conduction velocity.
来自大脑两侧的输入相互作用，在鸟类的层状核中创建双耳时间差（ITD）图谱。鉴于来自两侧的输入路径长度存在差异，目前尚不清楚在ITD敏感回路中，两侧的输入是如何以高精度进行匹配的。为了理解鸟类的这个问题，我们对输入轴突的几何结构及其相应的传导速度和潜伏期进行了建模。与现有的生理学数据一致，我们假设在到达层状核边界之前存在一个共同的潜伏期。我们分析了该模型的两种生物学实现方式，即鸡的单一ITD图谱和仓鸮的多个ITD图谱。对于双耳输入，由于同侧和对侧的初始共同潜伏期非常相似，我们可以将传导速度的自适应调节限制在核内。该模型的其他应用包括从一组测量值中同时推导多个传导速度，以及证明在仓鸮中具有相同ITD的轮廓不能与层状核的边界平行。对该模型预测的生理学测试证明了其有效性和稳健性。该模型可能不仅与听觉处理相关，还与其他需要对传导速度进行自适应调节的计算任务相关。
