Department of Biomedical Engineering, Center for Hearing Research, Boston University, Boston, MA 02215, USA.
J Neurophysiol. 2010 May;103(5):2355-71. doi: 10.1152/jn.00385.2009. Epub 2010 Jan 27.
The lateral superior olive (LSO) is the first nucleus in the ascending auditory pathway that encodes acoustic level information from both ears, the interaural level difference (ILD). This sensitivity is believed to result from the relative strengths of ipsilateral excitation and contralateral inhibition. The study reported here simulated sound-evoked responses of LSO chopper units with a focus on the role of the heterogeneity in membrane afterhyperpolarization (AHP) channels on spike interval statistics and on ILD encoding. A relatively simplified cell model was used so that the effects of interest could be isolated. Specifically, the amplitude and time constant of the AHP conductance within a leaky integrate-and-fire (LIF) cell model were studied. This extends the work of others who used a more physiologically detailed model. Results show that differences in these two parameters lead to both the distinctive chopper response patterns and to the level-dependent interval statistics as observed in vivo. In general, diverse AHP characteristics enable an enhanced contrast across population responses with respect to rate gain and temporal correlations. This membrane heterogeneity provides an internal, cell-specific dimension for the neural representation of stimulus information, allowing sensitivity to ILDs of dynamic stimuli.
外侧上橄榄核（LSO）是听觉上行通路中的第一个核团，它对来自双耳的声强信息（即两耳强度差，ILD）进行编码。这种敏感性被认为源于同侧兴奋和对侧抑制的相对强度。本研究通过模拟 LSO 切分神经元的声诱发反应，重点研究了膜后超极化（AHP）通道异质性在尖峰间隔统计和 ILD 编码中的作用。使用了一个相对简化的细胞模型，以便能够分离出感兴趣的效果。具体来说，研究了在漏积分和放电（LIF）细胞模型内 AHP 电导的幅度和时间常数。这扩展了其他人使用更生理详细模型的工作。结果表明，这两个参数的差异导致了独特的切分器响应模式以及体内观察到的与强度相关的间隔统计。总的来说，多样化的 AHP 特征为群体反应相对于率增益和时间相关性的对比度提供了一个内在的、细胞特异性的维度。这种膜异质性为刺激信息的神经表示提供了一个内部的、细胞特异性的维度，允许对动态刺激的 ILD 进行敏感检测。
