Perez-Flores Maria C, Verschooten Eric, Lee Jeong Han, Kim Hyo Jeong, Joris Philip X, Yamoah Ebenezer N
Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, United States.
Laboratory of Auditory Neurophysiology, Medical School, Campus Gasthuisberg, University of Leuven, Leuven, Belgium.
Elife. 2022 Mar 10;11:e74948. doi: 10.7554/eLife.74948.
Mechanosensation - by which mechanical stimuli are converted into a neuronal signal - is the basis for the sensory systems of hearing, balance, and touch. Mechanosensation is unmatched in speed and its diverse range of sensitivities, reaching its highest temporal limits with the sense of hearing; however, hair cells (HCs) and the auditory nerve (AN) serve as obligatory bottlenecks for sounds to engage the brain. Like other sensory neurons, auditory neurons use the canonical pathway for neurotransmission and millisecond-duration action potentials (APs). How the auditory system utilizes the relatively slow transmission mechanisms to achieve ultrafast speed, and high audio-frequency hearing remains an enigma. Here, we address this paradox and report that the mouse, and chinchilla, AN are mechanically sensitive, and minute mechanical displacement profoundly affects its response properties. Sound-mimicking sinusoidal mechanical and electrical current stimuli affect phase-locked responses. In a phase-dependent manner, the two stimuli can also evoke suppressive responses. We propose that mechanical sensitivity interacts with synaptic responses to shape responses in the AN, including frequency tuning and temporal phase locking. Combining neurotransmission and mechanical sensation to control spike patterns gives the mammalian AN a secondary receptor role, an emerging theme in primary neuronal functions.
机械感觉——通过它机械刺激被转换为神经元信号——是听觉、平衡觉和触觉等感觉系统的基础。机械感觉在速度和其多样的敏感度范围方面无与伦比，在听觉方面达到了其最高的时间极限；然而，毛细胞（HCs）和听神经（AN）是声音进入大脑的必经瓶颈。与其他感觉神经元一样，听觉神经元使用典型的神经传递途径和持续时间为毫秒级的动作电位（APs）。听觉系统如何利用相对缓慢的传递机制来实现超快速速度以及高频听力仍然是一个谜。在这里，我们解决了这个矛盾，并报告小鼠和毛丝鼠的听神经是机械敏感的，微小的机械位移会深刻影响其反应特性。模拟声音的正弦机械和电流刺激会影响锁相反应。以相位依赖的方式，这两种刺激也能引发抑制反应。我们提出，机械敏感性与突触反应相互作用，以塑造听神经中的反应，包括频率调谐和时间锁相。将神经传递和机械感觉结合起来控制放电模式赋予了哺乳动物听神经次要的感受器作用，这是初级神经元功能中的一个新出现的主题。
