Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 1051, Institut des Neurosciences de Montpellier, 34091 Montpellier, France.
Proc Natl Acad Sci U S A. 2014 Feb 4;111(5):1999-2004. doi: 10.1073/pnas.1319615111. Epub 2014 Jan 15.
Inner hair cells (IHCs) are the primary transducer for sound encoding in the cochlea. In contrast to the graded receptor potential of adult IHCs, immature hair cells fire spontaneous calcium action potentials during the first postnatal week. This spiking activity has been proposed to shape the tonotopic map along the ascending auditory pathway. Using perforated patch-clamp recordings, we show that developing IHCs fire spontaneous bursts of action potentials and that this pattern is indistinguishable along the basoapical gradient of the developing cochlea. In both apical and basal IHCs, the spiking behavior undergoes developmental changes, where the bursts of action potential tend to occur at a regular time interval and have a similar length toward the end of the first postnatal week. Although disruption of purinergic signaling does not interfere with the action potential firing pattern, pharmacological ablation of the α9α10 nicotinic receptor elicits an increase in the discharge rate. We therefore suggest that in addition to carrying place information to the ascending auditory nuclei, the IHCs firing pattern controlled by the α9α10 receptor conveys a temporal signature of the cochlear development.
内耳毛细胞（IHC）是耳蜗中声音编码的主要换能器。与成年 IHC 的分级受体潜力不同，未成熟的毛细胞在出生后的第一周内会自发地产生钙动作电位。这种尖峰活动被认为是沿听觉通路的音调图谱形成的。使用穿孔膜片钳记录，我们显示发育中的 IHC 会自发地爆发动作电位，并且这种模式沿着发育中的耳蜗的基底-顶侧梯度是无法区分的。在顶端和基底 IHC 中，尖峰行为都会发生发育变化，其中动作电位爆发倾向于以规则的时间间隔发生，并且在出生后的第一周结束时具有相似的长度。尽管嘌呤能信号的中断不会干扰动作电位的发放模式，但α9α10 烟碱受体的药理学消融会增加放电率。因此，我们认为除了将位置信息传递到上行听觉核外，由α9α10 受体控制的 IHC 发放模式还传达了耳蜗发育的时间特征。
