Rathcke Tamara, Lin Chia-Yuan
Department of Linguistics, Faculty of Humanities, University of Konstanz, 78464 Konstanz, Germany.
Modern Languages and Linguistics, School of Cultures and Languages, University of Kent, Canterbury CT2 7NR, UK.
Brain Sci. 2021 Sep 30;11(10):1303. doi: 10.3390/brainsci11101303.
Developmental dyslexia is typically defined as a difficulty with an individual's command of written language, arising from deficits in phonological awareness. However, motor entrainment difficulties in non-linguistic synchronization and time-keeping tasks have also been reported. Such findings gave rise to proposals of an underlying rhythm processing deficit in dyslexia, even though to date, evidence for impaired motor entrainment with the rhythm of natural speech is rather scarce, and the role of speech rhythm in phonological awareness is unclear. The present study aimed to fill these gaps. Dyslexic adults and age-matched control participants with variable levels of previous music training completed a series of experimental tasks assessing phoneme processing, rhythm perception, and motor entrainment abilities. In a rhythm entrainment task, participants tapped along to the perceived beat of natural spoken sentences. In a phoneme processing task, participants monitored for sonorant and obstruent phonemes embedded in nonsense strings. Individual sensorimotor skills were assessed using a number of screening tests. The results lacked evidence for a motor impairment or a general motor entrainment difficulty in dyslexia, at least among adult participants of the study. Instead, the results showed that the participants' performance in the phonemic task was predictive of their performance in the rhythmic task, but not vice versa, suggesting that atypical rhythm processing in dyslexia may be the consequence, but not the cause, of dyslexic difficulties with phoneme-level encoding. No evidence for a deficit in the entrainment to the syllable rate in dyslexic adults was found. Rather, metrically weak syllables were significantly less often at the center of rhythmic attention in dyslexic adults as compared to neurotypical controls, with an increased tendency in musically trained participants. This finding could not be explained by an auditory deficit in the processing of acoustic-prosodic cues to the rhythm structure, but it is likely to be related to the well-documented auditory short-term memory issue in dyslexia.
发育性阅读障碍通常被定义为个体在书面语言掌握方面存在困难，这是由语音意识缺陷引起的。然而，也有报道称在非语言同步和计时任务中存在运动同步困难。这些发现引发了关于阅读障碍中潜在节奏处理缺陷的提议，尽管迄今为止，关于自然语音节奏的运动同步受损的证据相当稀少，并且语音节奏在语音意识中的作用尚不清楚。本研究旨在填补这些空白。患有阅读障碍的成年人以及年龄匹配的、具有不同程度先前音乐训练的对照参与者完成了一系列实验任务，以评估音素处理、节奏感知和运动同步能力。在节奏同步任务中，参与者随着自然口语句子的感知节拍轻拍。在音素处理任务中，参与者监测嵌入在无意义字符串中的响音和阻塞音素。使用多项筛查测试评估个体的感觉运动技能。结果表明，至少在该研究的成年参与者中，没有证据表明阅读障碍存在运动障碍或普遍的运动同步困难。相反，结果显示参与者在音素任务中的表现可预测他们在节奏任务中的表现，但反之则不然，这表明阅读障碍中不典型的节奏处理可能是阅读障碍在音素水平编码方面困难的结果，而非原因。未发现成年阅读障碍者在音节速率同步方面存在缺陷的证据。相反，与神经典型对照组相比，成年阅读障碍者在节奏注意力中心出现韵律较弱音节的频率显著更低，而在接受过音乐训练的参与者中这种趋势有所增加。这一发现无法通过对节奏结构的声学韵律线索处理中的听觉缺陷来解释，但很可能与阅读障碍中已被充分记录的听觉短期记忆问题有关。
