Farahani Ehsan Darestani, Wouters Jan, van Wieringen Astrid
Research Group Experimental Oto-rhino-laryngology (ExpORL), Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium.
Front Aging Neurosci. 2020 Dec 4;12:596551. doi: 10.3389/fnagi.2020.596551. eCollection 2020.
Speech understanding problems are highly prevalent in the aging population, even when hearing sensitivity is clinically normal. These difficulties are attributed to changes in central temporal processing with age and can potentially be captured by age-related changes in neural generators. The aim of this study is to investigate age-related changes in a wide range of neural generators during temporal processing in middle-aged and older persons with normal audiometric thresholds. A minimum-norm imaging technique is employed to reconstruct cortical and subcortical neural generators of temporal processing for different acoustic modulations. The results indicate that for relatively slow modulations (<50 Hz), the response strength of neural sources is higher in older adults than in younger ones, while the phase-locking does not change. For faster modulations (80 Hz), both the response strength and the phase-locking of neural sources are reduced in older adults compared to younger ones. These age-related changes in temporal envelope processing of slow and fast acoustic modulations are possibly due to loss of functional inhibition, which is accompanied by aging. Both cortical (primary and non-primary) and subcortical neural generators demonstrate similar age-related changes in response strength and phase-locking. Hemispheric asymmetry is also altered in older adults compared to younger ones. Alterations depend on the modulation frequency and side of stimulation. The current findings at source level could have important implications for the understanding of age-related changes in auditory temporal processing and for developing advanced rehabilitation strategies to address speech understanding difficulties in the aging population.
言语理解问题在老年人群中非常普遍，即使听力敏感度在临床上是正常的。这些困难归因于随着年龄增长中央颞叶处理过程的变化，并且可能通过神经发生器的年龄相关变化来体现。本研究的目的是调查听力阈值正常的中年和老年人在颞叶处理过程中广泛神经发生器的年龄相关变化。采用最小范数成像技术重建不同声学调制下颞叶处理的皮质和皮质下神经发生器。结果表明，对于相对较慢的调制（<50 Hz），老年人神经源的反应强度高于年轻人，而锁相不变。对于较快的调制（80 Hz），与年轻人相比，老年人神经源的反应强度和锁相均降低。这些与年龄相关的慢、快声学调制的时间包络处理变化可能是由于功能性抑制的丧失，这与衰老有关。皮质（初级和非初级）和皮质下神经发生器在反应强度和锁相方面均表现出类似的年龄相关变化。与年轻人相比，老年人的半球不对称性也发生了改变。这种改变取决于调制频率和刺激侧。当前在源水平的发现可能对理解听觉颞叶处理中的年龄相关变化以及制定先进的康复策略以解决老年人群的言语理解困难具有重要意义。
