Subthreshold outward currents enhance temporal integration in auditory neurons.
Subthreshold outward currents enhance temporal integration in auditory neurons.
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阈下外向电流增强听觉神经元的时间整合。
DOI：
10.1007/s00422-003-0438-2
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Rinzel,John
中科院分区：
文献类型：
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作者：
Svirskis,Gytis;Dodla,Ramana;Rinzel,John
许多听觉神经元具有低阈值钾电流（IKLT），可增强其对快速和同步输入的反应性。我们目前的记录从沙鼠内侧上级橄榄（MSO）神经元在体外和建模结果，说明如何IKLT提高检测简短的信号，弱信号的噪声，和信号的重合（如需要的声音定位）。我们量化的增强效果ofIKLT的时间处理与几个措施：信噪比（SNR），反向相关或尖峰触发的平均输入电流，和耳间时间差（ITD）调谐曲线。为了表征在尖峰阈值以下激活的IKLT如何影响神经元朝向阈值的电压上升，即，它如何过滤输入，我们首先关注对微弱和噪声信号的响应。细胞和模型用计算机生成的随机输入的稳定弹幕刺激，模仿弱突触传导瞬变（“噪声”），以及较大但仍低于阈值的突触后传导EPSG（“信号”）。IKLT的降低降低了SNR，主要是由于自发放电的增加（更多的“假阳性”）。尖峰触发的反向相关表明IKLT缩短了尖峰产生的积分时间，同时提高了模型对模拟双耳输入的重合检测的时间选择性。此外，通过对MSO细胞的精确和快速抑制，ITD调谐偏向于斜率代码而不是位置代码（Brand等人，2002）。在几种方式中，低阈值外向电流被认为是听觉神经元中弱信号和强信号的整合。
Many auditory neurons possess low-threshold potassium currents (IKLT) that enhance their responsiveness to rapid and coincident inputs. We present recordings from gerbil medial superior olivary (MSO) neurons in vitro and modeling results that illustrate howIKLTimproves the detection of brief signals, of weak signals in noise, and of the coincidence of signals (as needed for sound localization). We quantify the enhancing effect ofIKLTon temporal processing with several measures: signal-to-noise ratio (SNR), reverse correlation or spike-triggered averaging of input currents, and interaural time difference (ITD) tuning curves. To characterize howIKLT, which activates below spike threshold, influences a neuron’s voltage rise toward threshold, i.e., how it filters the inputs, we focus first on the response to weak and noisy signals. Cells and models were stimulated with a computer-generated steady barrage of random inputs, mimicking weak synaptic conductance transients (the “noise”), together with a larger but still subthreshold postsynaptic conductance, EPSG (the “signal”). Reduction ofIKLTdecreased the SNR, mainly due to an increase in spontaneous firing (more “false positive”). The spike-triggered reverse correlation indicated thatIKLTshortened the integration time for spike generation.IKLTalso heightened the model’s timing selectivity for coincidence detection of simulated binaural inputs. Further, ITD tuning is shifted in favor of a slope code rather than a place code by precise and rapid inhibition onto MSO cells (Brand et al. 2002). In several ways, low-threshold outward currents are seen to shape integration of weak and strong signals in auditory neurons.