Aging affects neural precision of speech encoding.
Aging affects neural precision of speech encoding.
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DOI：
10.1523/jneurosci.2176-12.2012
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发表时间：
2012-10-10
期刊：
影响因子：
--
通讯作者：
Kraus N
中科院分区：
文献类型：
--
作者：
Anderson S;Parbery-Clark A;White-Schwoch T;Kraus N
老年人经常报告他们能听到所说的话，但不能理解其含义，特别是在噪音中。这种困难可能是由于无法处理语音中快速变化的成分而产生的。衰老伴随着神经处理的普遍减慢和神经抑制的减少，这两者都可能干扰听觉和其他感觉领域的时间处理。与听觉相关的抑制性神经递质水平的降低和延迟的神经恢复可以导致听觉系统的时间精度降低。降低的精度可能导致神经计时延迟、神经响应幅度的降低以及在处理语音中的快速声学变化方面的不利因素。听觉脑干反应（ABR）是一种头皮记录的电位，以其捕获皮层下听觉核团内精确神经同步的能力而闻名;因此，我们假设时间精度的损失导致皮层下时间延迟并降低反应一致性和幅度。为了评估这一假设，我们记录了听力正常的年轻人（18至30岁）和老年人（60至67岁）的语音音节/da/的ABR。老年人有延迟的ABR，特别是在快速变化的共振峰转换，和更大的反应变异性。我们还发现，老年人有减少锁相和较小的响应幅度比年轻的成年人。两者合计，我们的研究结果支持的理论，老年人有一个损失的时间精度在皮层下编码的声音，这可能占，至少部分，他们的困难与言语知觉。
Older adults frequently report they can hear what is said but cannot understand the meaning, especially in noise. This difficulty may arise from the inability to process rapidly changing elements of speech. Aging is accompanied by a general slowing of neural processing and decreased neural inhibition, both of which likely interfere with temporal processing in auditory and other sensory domains. Age-related reductions in inhibitory neurotransmitter levels and delayed neural recovery can contribute to decreases in the auditory system’s temporal precision. Decreased precision may lead to neural timing delays, reductions in neural response magnitude, and a disadvantage in processing the rapid acoustic changes in speech. The auditory brainstem response (ABR), a scalp-recorded electrical potential, is known for its ability to capture precise neural synchrony within subcortical auditory nuclei; therefore, we hypothesized that a loss of temporal precision results in subcortical timing delays and decreases in response consistency and magnitude. To assess this hypothesis, we recorded ABRs to the speech syllable /da/ in normal hearing younger (ages 18 to 30) and older adult humans (60 to 67). Older adults had delayed ABRs, especially in response to the rapidly changing formant transition, and greater response variability. We also found that older adults had decreased phase locking and smaller response magnitudes than younger adults. Taken together, our results support the theory that older adults have a loss of temporal precision in subcortical encoding of sound, which may account, at least in part, for their difficulties with speech perception.