Your genes decide what you are listening to.
Your genes decide what you are listening to.
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DOI：
10.1080/19336950.2017.1348870
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发表时间：
2017-09-03
期刊：
影响因子：
--
通讯作者：
Kopp-Scheinpflug C
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文献类型：
--
作者：
Kopp-Scheinpflug C
离子通道，特别是低电压激活钾通道（KLVA）保护神经元的兴奋性和形状的个别神经元的频率放电模式。Lu等人的文章，1发表在本期演示了KLVA通道的差异表达如何产生独特的过滤特性，将神经元调谐到其刺激特异性输入。在听觉系统中，锁相到刺激波形的特定相位是对周期性刺激（如声波）的时间模式进行编码的有效方式。然而，对于每个刺激周期产生理想的一个尖峰对于该计算造成2个困难：首先，低刺激频率具有更长的刺激周期，其将在每个周期容纳多于一个尖峰，并且因此导致刺激的减少的时间表示。其次，对于更高的刺激频率，单个刺激周期接近神经元的不应期，从而危及其在每个周期产生甚至一个尖峰的能力。显然，大脑克服了这一困难，但问题是哪些特定的内在和/或突触属性注定听觉神经元锁相到低或更高的刺激频率已在最近的两项研究中得到解决。Lu 1和Oline 2都利用了鸡耳蜗核（nucleus magnocellularis; NM），其中突触会聚的梯度和KLVA的差异表达被叠加到核的音调分布图上。调整到低频输入的神经元通过整合多个重合的亚阈值输入克服了每个周期产生一个以上尖峰的“问题”。[2]这只是因为KLVA在这些低频神经元中的表达很低，因为低频刺激的缓慢斜率会激活KLVA并阻止时间总和。事实上，NM神经元处理中高刺激频率显示出更高的KLVA表达，导致更快的膜时间常数和时间总和的限制。将不同频率的正弦电流注入到中高频神经元中，很好地证明了它们的滤波特性，这导致对低频输入的拒绝，并促进对更高刺激频率的单尖峰响应。1，2 KLVA在中高频神经元中的高表达使其静息膜电位显著超极化。除了消除电压激活钠通道的失活外，KLVA引起的这种超极化还参与超极化激活的环核苷酸调节（HCN）通道，它们共同进一步降低神经元膜的输入电阻并加快其膜时间常数。哺乳动物耳蜗核神经元中KLVA和HCN的表达是共同调节的。3这表明与低频NM神经元相比，中高频神经元中HCN通道的表达更高。KLVA和HCN一起提供了对快速高频输入进行编码的理想组合。给定输入收敛、离子通道表达、输出滤波特性或甚至
Ion channels, in particular low-voltage activated potassium channels (KLVA) guard neuronal excitability and shape individual neurons’ frequency-firing patterns. The article by Lu et al., 1 published in the current issue demonstrates how differential expression of KLVA channels generates unique filtering properties that tune neurons to their stimulus-specific inputs. In the auditory system, phase-locking to a specific phase of the stimulus waveform is an effective way to encode the temporal pattern of a periodic stimulus like a soundwave. However, generating ideally one spike for each stimulus cycle poses 2 difficulties for this computation: First, low stimulus frequencies have longer stimulus cycles which would accommodate more than one spike per cycle and thus leading to a reduced temporal representation of the stimulus. Second, for higher stimulus frequencies a single stimulus cycle approaches the neuron’s refractory period–jeopardizing its ability to generate even one spike for each cycle. Obviously, the brain overcomes this difficulty, but the question of which particular intrinsic and/or synaptic properties destine auditory neurons to phase-lock to either low-or higher stimulus frequencies has been addressed in 2 recent studies. Lu 1 and Oline 2 both took advantage of the chick cochlear nucleus (nucleus magnocellularis; NM) where gradients of synaptic convergence and differential expression of KLVA are superimposed onto the tonotopic map of the nucleus. Neurons tuned to lowfrequency input overcome the “problem” of generating more than one spike per cycle by integrating over multiple coinciding subthreshold inputs. 2 This is only possible because KLVA expression is low in these lowfrequency neurons, as the slow slope of low-frequency stimuli would activate KLVA and prevent temporal summation. 2 Indeed, NM neurons processing mid-to-high stimulus frequencies show a much higher expression of KLVA resulting in faster membrane time constants and limitation of temporal summation. Injecting sinusoidal currents of different frequencies into mid-to-high frequency neurons nicely demonstrated their filtering properties which result in rejection of low-frequency inputs and foster single spike responses to higher stimulus frequencies. 1, 2The high expression of KLVA in mid-to-high frequency neurons significantly hyperpolarizes their resting membrane potential. Besides removing inactivation from voltage-activated sodium channels, this hyperpolarization caused by KLVA also engages hyperpolarization-activated cyclic nucleotide modulated (HCN) channels, which together further reduce the input resistance of the neurons membrane and speed up their membrane time constant. The expression of KLVA and HCN is co-regulated in neurons of the mammalian cochlear nucleus. 3 Here this would suggest a higher expression of HCN channels in mid-to-high frequency neurons compared with low-frequency NM neurons. Together KLVA and HCN provide an ideal composition to encode fast, high-frequency inputs. Given such differences in input convergence, ion channel expression, output filtering properties or even
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影响因子：
5.3
作者：
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