Dysmyelination of auditory afferent axons increases the jitter of action potential timing during high-frequency firing.
Dysmyelination of auditory afferent axons increases the jitter of action potential timing during high-frequency firing.
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DOI：
10.1523/jneurosci.3389-12.2013
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发表时间：
2013-05-29
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影响因子：
--
通讯作者：
von Gersdorff H
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文献类型：
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作者：
Kim JH;Renden R;von Gersdorff H
听觉神经病与声音诱发的信号的暂时敏锐度有关，这可能与髓磷脂损失有关。在这里，我们使用长evans Shaker（LES）大鼠（一种紧凑型突变体）调查了固定终端的花萼的兴奋由于髓磷脂碱性蛋白质的遗传缺失（MBP），我们在相对成熟的产后年龄（出生后15-17天）没有发生髓鞘包裹。 AP传播速度。 APS以高达1 kHz的速度而没有失败，LES Calyces无法直接录制到突触前的Calyx终端AP波段，显示髓磷脂损失不会影响AP Spike上峰和下stre肌的动力学，但降低了均质的降低。去极化并增强了LES大鼠AP峰值后的快速后磨砂峰。快速的AP传播，但也为了精确的突触前AP触发，可以最大程度地减少尖峰抖动和失败，这对于在听觉脑干中准确处理声音信号至关重要。
Auditory neuropathies are linked to loss of temporal acuity of sound-evoked signals, which may be related to myelin loss. However, it is not known how myelin loss affects the waveform and temporal precision of action potentials (APs) in auditory CNS nerve terminals. Here we investigated the excitability of the calyx of Held terminal in dysmyelinated auditory brainstems using the Long-Evans Shaker (LES) rat, a spontaneous mutant where compact myelin wrapping does not occur due to a genetic deletion of myelin basic protein (MBP). We found at relatively mature postnatal ages (15–17 days after birth) LES rat calyces showed prolonged spike latencies, indicative of a 3-fold reduction in the AP propagation velocity. Furthermore, LES rat afferent fiber-evoked APs showed a pronounced loss of temporal precision, even at low stimulation frequencies (10 Hz). While normal calyces were able to fire APs without failures at impressive rates of up to 1 kHz, LES calyces were unable to do so. Direct recordings of the presynaptic calyx terminal AP waveform revealed that myelin loss does not affect the AP spike upstroke and downstroke kinetics, but dysmyelination reduces the after-depolarization and enhances the fast after-hyperpolarization peak following the AP spike in the LES rat. Taken together these findings show that proper myelination is essential not only for fast AP propagation, but also for precise presynaptic AP firing that minimizes both spike jitter and failures, two characteristics critically important for the accurate processing of sound signals in the auditory brainstem.