Aging is associated with an exaggerated representation of the speech envelope in auditory cortex. The relationship between this age-related exaggerated response and a listener's ability to understand speech in noise remains an open question. Here, information-theory-based analysis methods are applied to magnetoencephalography (MEG) recordings of human listeners, investigating their cortical responses to continuous speech, using the novel non-linear measure of phase-locked mutual information between the speech stimuli and cortical responses. The cortex of older listeners shows an exaggerated level of mutual information, compared to younger listeners, for both attended and unattended speakers. The mutual information peaks for several distinct latencies: early (~50 ms), middle (~100 ms) and late (~200 ms). For the late component, the neural enhancement of attended over unattended speech is affected by stimulus SNR, but the direction of this dependency is reversed by aging. Critically, in older listeners and for the same late component, greater cortical exaggeration is correlated with decreased behavioral inhibitory control. This negative correlation also carries over to speech intelligibility in noise, where greater cortical exaggeration in older listeners is correlated with worse speech intelligibility scores. Finally, an age-related lateralization difference is also seen for the ~100 ms latency peaks, where older listeners show a bilateral response compared to younger listeners' right-lateralization. Thus, this information-theory-based analysis provides new, and less coarse-grained, results regarding age-related change in auditory cortical speech processing, and its correlation with cognitive measures, compared to related linear measures.

中文翻译：

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老年听众言语的夸大皮层表现：互信息分析。

衰老与听觉皮层中语音包络的夸张表现有关。这种与年龄相关的夸张反应与听者在噪音中理解语音的能力之间的关系仍然是一个悬而未决的问题。在这里，基于信息论的分析方法被应用于人类听众的脑磁图 (MEG) 记录，研究他们对连续语音的皮层反应，使用语音刺激和皮层反应之间的锁相互信息的新型非线性测量。与年轻的听众相比，老年听众的大脑皮层显示出夸大的相互信息水平，无论是有人参与还是无人参与的演讲者。几个不同延迟的互信息峰值：早期（~50 ms）、中间（~100 ms）和晚期（~200 ms）。对于后期组件，有人参与的语音对无人参与的神经增强受刺激信噪比的影响，但这种依赖的方向随着年龄的增长而逆转。至关重要的是，在年长的听众和相同的晚期成分中，更大的皮质夸张与行为抑制控制的减少相关。这种负相关性也影响到噪声中的语音清晰度，在这种情况下，年龄较大的听众的皮质夸大程度与较差的语音清晰度得分相关。最后，对于约 100 毫秒的延迟峰值，还可以看到与年龄相关的侧化差异，与年轻听众的右侧化相比，年长的听众表现出双边反应。因此，这种基于信息论的分析提供了关于听觉皮层语音处理中与年龄相关的变化的新的、不那么粗粒度的结果，