Effects of aging on peripheral and central auditory processing in rats
Effects of aging on peripheral and central auditory processing in rats
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DOI：
10.1111/ejn.13302
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发表时间：
2016-08-01
影响因子：
3.4
通讯作者：
Guillemot, Jean-Paul
中科院分区：
文献类型：
--
作者：
Costa, Margarida;Lepore, Franco;Guillemot, Jean-Paul
听力损失是老年人口的一个标志。听觉知觉的下降会导致声源定位能力的下降，并降低言语知觉，特别是在噪音中。除了丧失外周听力敏感度外，还表现出更复杂的中枢结构的变化。与此相关，本研究对大鼠上丘深层的听觉定向映射进行了研究。因此，麻醉的成年SD大鼠(10月龄)和老年大鼠(22月龄)接受耳声发射失真产物(DPOAEs)检查，以评估耳蜗功能。然后，评估听觉脑干反应(ABR)，随后进行细胞外单位记录，以确定与年龄相关的对中枢听觉功能的影响。老年大鼠的DPOAE波幅水平有所降低，但仍在3.0~24.0 kHZ之间。老年大鼠的ABR阈值在听性脑干早期(耳蜗核-波II)显著升高。在上丘，阈值增加，定向感受野的调谐宽度明显变宽。此外，老年大鼠神经元之间没有系统的定向空间排列，这意味着听觉定向映射的地形图组织被取消。这些结果表明，在某种程度上，听觉定向空间图的恶化可以归因于年龄相关的听觉加工更中枢、更知觉阶段的功能障碍。
Hearing loss is a hallmark sign in the elderly population. Decline in auditory perception provokes deficits in the ability to localize sound sources and reduces speech perception, particularly in noise. In addition to a loss of peripheral hearing sensitivity, changes in more complex central structures have also been demonstrated. Related to these, this study examines the auditory directional maps in the deep layers of the superior colliculus of the rat. Hence, anesthetized Sprague-Dawley adult (10months) and aged (22months) rats underwent distortion product of otoacoustic emissions (DPOAEs) to assess cochlear function. Then, auditory brainstem responses (ABRs) were assessed, followed by extracellular single-unit recordings to determine age-related effects on central auditory functions. DPOAE amplitude levels were decreased in aged rats although they were still present between 3.0 and 24.0 kHz. ABR level thresholds in aged rats were significantly elevated at an early (cochlear nucleus - wave II) stage in the auditory brainstem. In the superior colliculus, thresholds were increased and the tuning widths of the directional receptive fields were significantly wider. Moreover, no systematic directional spatial arrangement was present among the neurons of the aged rats, implying that the topographical organization of the auditory directional map was abolished. These results suggest that the deterioration of the auditory directional spatial map can, to some extent, be attributable to age-related dysfunction at more central, perceptual stages of auditory processing.