Inhibitory synaptic release properties are topographically distributed in auditory circuitry.
Inhibitory synaptic release properties are topographically distributed in auditory circuitry.
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抑制性突触释放特性在听觉电路中按地形分布。
DOI：
10.1113/jphysiol.2012.236810
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Burger,RMichael
中科院分区：
文献类型：
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作者：
Burger,RMichael
突触生理学得益于对脑干听觉系统回路的研究，在脑干听觉系统中，神经计算的专门化很容易与功能相关。这包括众所周知的对大型突触的探索，如花萼（Forsythe, 1994; Schneggenburger & Forsythe, 2006），以及比较两耳输入的神经元的生物物理和形态专门化。在鸟类中，层状核神经元（NL）计算声音刺激到达两只耳朵的时间差异。这些间时差（ITDs）是一种声学线索，它随着声源在空间中的位置而系统地变化。对过渡段的计算使动物能够准确地定位声源。过渡段非常小，大约几十到几百微秒，主要取决于头部宽度。NL神经元能够在整个动态范围内，在狭窄的过渡段生理范围内改变其放电速率。因此，NL电路可以精确地操作，尽管有非常严格的时间限制。NL面临的另一个时间约束来自于刺激频率。NL通路中的神经元对声波波形表现出锁相响应，以便对信号的时间特征进行编码。锁相神经元对10 ~ 2000赫兹的信号在刺激波形的特定相位做出精确的反应。因此，对特定NL神经元的计算需求既取决于刺激位置给出的过渡段，也取决于NL神经元调整到的刺激频率。这些计算需求推动了NL电路中许多生理专门化的进化。
Synaptic physiology has benefited from investigation of the circuitry of the brainstem auditory system where specializations in neural computation are readily related to function. This includes the widely known exploration of large synapses such as the Calyx of Held (Forsythe, 1994; Schneggenburger & Forsythe, 2006), as well as biophysical and morphological specialization in neurones that compare input from the two ears. In birds, neurones of nucleus laminaris (NL) compute the difference in a sound stimulus’s arrival time at the two ears. These interaural time disparities (ITDs) are an acoustic cue that varies systematically with a sound source’s position in space. Computation of ITD allows animals to accurately localize sound sources. ITDs are very small, on the order of tens to hundreds of microseconds, and depend primarily on head width. An NL neurone is capable of varying its firing rate over its entire dynamic range within this narrow physiological range of ITDs. Thus, the NL circuitry operates with precision despite exceedingly restrictive temporal constraints.Another temporal constraint faced by NL arises from stimulus frequency. Neurones in the NL pathway exhibit phase-locked responses to the acoustic waveform in order to encode the temporal features of the signal. Phase-locked neurones respond precisely at a particular phase of the stimulus waveform for signals from 10 to about 2000 Hz. Thus, the computational demand on a particular NL neurone depends both on the ITD given by stimulus location, and by the stimulus frequency to which the NL neurone is tuned. These computational demands have driven the evolution of many physiological specializations in NL circuitry.