Jossinger Sivan, Yablonski Maya, Amir Ofer, Ben-Shachar Michal
The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel.
Department of Communication Disorders, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Neurobiol Lang (Camb). 2024 Aug 15;5(3):676-700. doi: 10.1162/nol_a_00098. eCollection 2024.
Fluent speech production is a complex task that spans multiple processes, from conceptual framing and lexical access, through phonological encoding, to articulatory control. For the most part, imaging studies portraying the neural correlates of speech fluency tend to examine clinical populations sustaining speech impairments and focus on either lexical access or articulatory control, but not both. Here, we evaluated the contribution of the cerebellar peduncles to speech fluency by measuring the different components of the process in a sample of 45 neurotypical adults. Participants underwent an unstructured interview to assess their natural speaking rate and articulation rate, and completed timed semantic and phonemic fluency tasks to assess their verbal fluency. Diffusion magnetic resonance imaging with probabilistic tractography was used to segment the bilateral cerebellar peduncles (CPs) and frontal aslant tract (FAT), previously associated with speech production in clinical populations. Our results demonstrate distinct patterns of white matter associations with different fluency components. Specifically, verbal fluency is associated with the right superior CP, whereas speaking rate is associated with the right middle CP and bilateral FAT. No association is found with articulation rate in these pathways, in contrast to previous findings in persons who stutter. Our findings support the contribution of the cerebellum to aspects of speech production that go beyond articulatory control, such as lexical access, pragmatic or syntactic generation. Further, we demonstrate that distinct cerebellar pathways dissociate different components of speech fluency in neurotypical speakers.
流利的言语产生是一项复杂的任务，它跨越多个过程，从概念构建和词汇提取，经过语音编码，到发音控制。在很大程度上，描绘言语流畅性神经关联的成像研究倾向于检查患有言语障碍的临床人群，并专注于词汇提取或发音控制其中之一，而非两者兼顾。在此，我们通过测量45名神经典型成年人样本中该过程的不同组成部分，评估了小脑脚对言语流畅性的贡献。参与者接受了一次非结构化访谈，以评估他们的自然语速和发音速度，并完成了限时语义和音素流畅性任务，以评估他们的言语流畅性。利用带有概率性纤维束成像的扩散磁共振成像来分割双侧小脑脚（CPs）和额斜束（FAT），这两者先前在临床人群中与言语产生相关。我们的结果表明，白质与不同流畅性组成部分存在不同的关联模式。具体而言，言语流畅性与右侧上小脑脚相关，而语速与右侧中小脑脚和双侧额斜束相关。与口吃者先前的研究结果相反，在这些通路中未发现与发音速度有关联。我们的研究结果支持小脑对言语产生中超越发音控制的方面，如词汇提取、语用或句法生成所起的作用。此外，我们证明在神经典型的说话者中，不同的小脑通路区分了言语流畅性的不同组成部分。
