Gold Joshua R, Bajo Victoria M
Department of Physiology, Anatomy and Genetics, University of Oxford Oxford, UK.
Front Neurosci. 2014 May 23;8:110. doi: 10.3389/fnins.2014.00110. eCollection 2014.
The brain displays a remarkable capacity for both widespread and region-specific modifications in response to environmental challenges, with adaptive processes bringing about the reweighing of connections in neural networks putatively required for optimizing performance and behavior. As an avenue for investigation, studies centered around changes in the mammalian auditory system, extending from the brainstem to the cortex, have revealed a plethora of mechanisms that operate in the context of sensory disruption after insult, be it lesion-, noise trauma, drug-, or age-related. Of particular interest in recent work are those aspects of auditory processing which, after sensory disruption, change at multiple-if not all-levels of the auditory hierarchy. These include changes in excitatory, inhibitory and neuromodulatory networks, consistent with theories of homeostatic plasticity; functional alterations in gene expression and in protein levels; as well as broader network processing effects with cognitive and behavioral implications. Nevertheless, there abounds substantial debate regarding which of these processes may only be sequelae of the original insult, and which may, in fact, be maladaptively compelling further degradation of the organism's competence to cope with its disrupted sensory context. In this review, we aim to examine how the mammalian auditory system responds in the wake of particular insults, and to disambiguate how the changes that develop might underlie a correlated class of phantom disorders, including tinnitus and hyperacusis, which putatively are brought about through maladaptive neuroplastic disruptions to auditory networks governing the spatial and temporal processing of acoustic sensory information.
大脑在应对环境挑战时，展现出广泛且区域特异性的显著适应能力，通过适应性过程对神经网络中的连接进行重新加权，这被认为是优化性能和行为所必需的。作为一种研究途径，围绕哺乳动物听觉系统变化展开的研究，从脑干延伸至皮层，揭示了大量在损伤后感觉功能紊乱的背景下起作用的机制，这些损伤包括病变、噪声创伤、药物或与年龄相关的损伤。近期研究特别感兴趣的是听觉处理的那些方面，在感觉功能紊乱后，这些方面在听觉层级的多个（即便不是所有）层面都会发生变化。这些变化包括兴奋性、抑制性和神经调节网络的改变，这与稳态可塑性理论一致；基因表达和蛋白质水平的功能改变；以及具有认知和行为影响的更广泛的网络处理效应。然而，关于这些过程中哪些可能仅仅是原始损伤的后遗症，哪些实际上可能会导致机体应对感觉功能紊乱环境的能力出现适应不良的进一步退化，存在大量争议。在这篇综述中，我们旨在研究哺乳动物听觉系统在特定损伤后如何做出反应，并厘清所发生的变化如何可能构成一类相关的幻听障碍（包括耳鸣和听觉过敏）的基础，这些障碍据推测是通过对负责声音感觉信息时空处理的听觉网络进行适应不良的神经可塑性破坏而产生的。
