Olivocochlear projections contribute to superior intensity coding in cochlear nucleus small cells.
Olivocochlear projections contribute to superior intensity coding in cochlear nucleus small cells.
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DOI：
10.1113/jp282262
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发表时间：
2022-01
影响因子：
5.5
通讯作者：
Shore, Susan E.
中科院分区：
文献类型：
--
作者：
Hockley, Adam;Wu, Calvin;Shore, Susan E.
理解通信信号，特别是在嘈杂的环境中，对社交互动至关重要。然而，随着年龄的增长，耳蜗损伤和随后的听觉神经纤维退化会破坏听觉信号。耳蜗核内分布着最易接受的中、高阈值听神经纤维，其中小细胞是唯一接受这种输入的细胞。此外，小细胞投射到内侧橄榄耳蜗（MOC）神经元，这反过来又将分支的侧枝送回小细胞帽（SCC）。在这里，我们使用单单位的记录来验证小细胞的放电特性，并证明在这个细胞类的上级强度编码。我们显示匡威的效果时，激活/阻断MOC系统，表明小细胞独特的编码特性，促进直接胆碱能输入从MOC系统。小小区还在存在背景噪声的情况下维持音调级编码。最后，小细胞精确地编码低频调制比其他腹CN（VCN）细胞类型更准确，证明准确的包络编码可能是重要的发声处理。这些结果突出了小细胞橄榄耳蜗电路作为在噪声环境中的信号处理的关键球员，这可能会选择性地在老化或噪声损伤后退化。
Understanding communication signals, especially in noisy environments, is crucial to social interactions. Yet, as we age, acoustic signals can be disrupted by cochlear damage and the subsequent auditory nerve fiber degeneration. The most vulnerable—medium and high-threshold—auditory nerve fibers innervate various cell types in the cochlear nucleus, among which, the small cells are unique in receiving this input exclusively. Furthermore, small cells project to medial olivocochlear (MOC) neurons, which in turn send branched collaterals back into the small cell cap (SCC). Here, we use single-unit recordings to characterise small cell firing characteristics and demonstrate superior intensity coding in this cell class. We show converse effects when activating/blocking the MOC system, demonstrating that small-cell unique coding properties are facilitated by direct cholinergic input from the MOC system. Small cells also maintain tone-level coding in the presence of background noise. Finally, small cells precisely code low-frequency modulation more accurately than other ventral CN (VCN) cell types, demonstrating accurate envelope coding that may be important for vocalisation processing. These results highlight the small cell–olivocochlear circuit as a key player in signal processing in noisy environments, which may be selectively degraded in aging or after noise insult.