年龄相关的包络线索神经编码变化:外周下降和中枢补偿。

Age-related Changes in Neural Coding of Envelope Cues: Peripheral Declines and Central Compensation.

机构信息

Department of Otolaryngology, Harvard Medical School, and Eaton-Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.

Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47906, USA.

出版信息

Neuroscience. 2019 May 21;407:21-31. doi: 10.1016/j.neuroscience.2018.12.007. Epub 2018 Dec 14.

Abstract

Aging listeners often experience difficulties in perceiving temporally complex acoustic cues in noisy environments. These difficulties likely have neurophysiological contributors from various levels of auditory processing. Cochlear synapses between inner hair cells and auditory nerve fibers exhibit a progressive decline with age which is not reflected in the threshold audiogram. The functional consequences of this loss for the coding of suprathreshold sound remain poorly understood. Recent studies suggest that cochlear synaptopathy results in degraded representations of temporal envelope cues at the earliest levels of the auditory pathway. Central nuclei downstream of the auditory nerve exhibit a compensatory plasticity in response to this deafferentation, in the form of altered gain. This results in a modulation frequency selective increase in the representation of envelope cues at the level of the auditory midbrain and cortex. These changes may be shaped by mechanisms such as decreased inhibitory neurotransmission occurring with age across various central auditory nuclei. Altered representations of the differing temporal components of speech due to these interactions between multiple levels of the auditory pathway may contribute to the age-related difficulties hearing speech in noisy environments.

摘要

衰老的听众在嘈杂环境中感知时间复杂的声音线索往往存在困难。这些困难可能有来自听觉处理各个层面的神经生理学贡献。内毛细胞和听神经纤维之间的耳蜗突触随年龄增长逐渐下降,但在听力图中并未反映出来。这种损失对超阈值声音编码的功能后果仍知之甚少。最近的研究表明,耳蜗突触病导致听觉通路最早水平上的时间包络线索的表示退化。听神经下游的中枢核在去传入的情况下表现出代偿性可塑性,表现为增益改变。这导致在听觉中脑和皮质水平上,包络线索表示的调制频率选择性增加。这些变化可能受到各种中枢听觉核中随年龄发生的抑制性神经传递减少等机制的影响。由于听觉通路多个层次之间的这种相互作用,言语不同时间成分的表示发生改变,可能导致在嘈杂环境中听到言语的年龄相关困难。

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