Upregulation of cognitive control networks in older adults' speech comprehension.
Upregulation of cognitive control networks in older adults' speech comprehension.
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DOI：
10.3389/fnsys.2013.00116
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发表时间：
2013
影响因子：
3
通讯作者：
Obleser J
中科院分区：
文献类型：
--
作者：
Erb J;Obleser J
言语理解能力随着年龄的增长和与年龄相关的听力损失而下降，但目前还不清楚这种下降如何在中枢神经机制方面表现出来。目前的研究检查了一组老年人（年龄56-77岁，n = 16，有不同程度的感觉神经性听力损失）的神经言语处理，并将其与一组年轻人（年龄22-31岁，n = 30，自我报告听力正常）进行了比较。在一个功能性磁共振成像实验中，听众听到并重复回退化的句子（4波段声码，其中声学信号的时间包络被保留，而频谱信息基本上退化）。从行为上看，老年人适应退化语音的速度与年轻听众相同，尽管他们对退化语音的整体理解较低。在神经方面，老年人和年轻人都依赖左前额叶来降低清晰的言语感知。然而，老年人的前牙嵌塞依赖于听力敏锐度。年轻人还使用前扣带皮层（ACC）。有趣的是，这种年龄组×退化的相互作用是由老年人的动态范围减少驱动的，老年人在退化和清晰的语音中表现出较高的ACC活性水平，这与认知控制的持续上调一致，而与任务难度无关。对于正确的言语理解，老年人依赖于额中回，除了一个核心的言语理解网络招募的年轻人暗示的补偿机制。总之，结果表明，老年人越来越多地招募认知控制网络，即使在最佳听力条件下，以牺牲这些系统的动态范围为代价。
Speech comprehension abilities decline with age and with age-related hearing loss, but it is unclear how this decline expresses in terms of central neural mechanisms. The current study examined neural speech processing in a group of older adults (aged 56–77, n = 16, with varying degrees of sensorineural hearing loss), and compared them to a cohort of young adults (aged 22–31, n = 30, self-reported normal hearing). In a functional MRI experiment, listeners heard and repeated back degraded sentences (4-band vocoded, where the temporal envelope of the acoustic signal is preserved, while the spectral information is substantially degraded). Behaviorally, older adults adapted to degraded speech at the same rate as young listeners, although their overall comprehension of degraded speech was lower. Neurally, both older and young adults relied on the left anterior insula for degraded more than clear speech perception. However, anterior insula engagement in older adults was dependent on hearing acuity. Young adults additionally employed the anterior cingulate cortex (ACC). Interestingly, this age group × degradation interaction was driven by a reduced dynamic range in older adults who displayed elevated levels of ACC activity for both degraded and clear speech, consistent with a persistent upregulation in cognitive control irrespective of task difficulty. For correct speech comprehension, older adults relied on the middle frontal gyrus in addition to a core speech comprehension network recruited by younger adults suggestive of a compensatory mechanism. Taken together, the results indicate that older adults increasingly recruit cognitive control networks, even under optimal listening conditions, at the expense of these systems’ dynamic range.