Collaborative research: role of the motor system in phonological and phonetic processing

在世界各地的语言中，某些发音组合出现的频率比其他语言更高。然而，这些规律的基础尚不清楚。一些研究人员认为，像“lbog”这样的组合很少见，因为它们需要比“博客”这样的组合更复杂的发音手势。另一种可能性是，像“lbog”这样的组合往往会被避免，因为它们违反了对可允许的音节结构的更抽象的语言限制。研究人员将使用非侵入性脑刺激和行为方法，通过检查发音运动系统在言语感知中的作用来评估这些可能性。弄清言语运动过程和语言知识的相对贡献对于言语语言障碍的诊断和治疗、第一语言和第二语言习得以及阅读至关重要。本研究探讨了具体化和抽象化在言语知觉中的作用。它认为，语音在多个层面上(具体化语音和抽象语音规则)表征，对动作模拟的敏感性不同，这取决于(A)分析水平和(B)说话人的语言经验。拟议的实验通过将大脑刺激和行为实验相结合来验证这一假设。使用MRI引导的经颅磁刺激(TMS)，研究小组将扰乱与运动动作相关的大脑区域(BA4中左侧口轮匝肌的皮质表示)和与组合语音操作相关的大脑区域(左侧三角部、PTR、BA 45)的活动，并评估对两项不同依赖语音处理或假定抽象的音节结构语音计算的任务的影响。虽然任务或大脑区域都不太可能对单一水平的分析具有选择性，但这些实验衡量的是它们的参与程度是否不同。如果语音分类需要运动模拟，那么BA4的中断对语音分类的影响应该大于对音节结构计算的影响。另一方面，如果音节结构的计算依赖于PTR所影响的非实体过程，那么BA45的干扰对音节结构的影响应该比对语音分类的影响更大。项目1和2与说英语和俄语的人(在音节清单中形成对比的语言)检验这些预测。这组比较评估了在不同任务中运动系统参与的经验依赖的可塑性或一致性。项目3和4机械地抑制了发音。如果BA4对语音分类的更大贡献反映了它在运动模拟中的作用，那么TMS对口轮匝肌的破坏和机械抑制应该是一致的。

Across the world's languages, certain sound combinations occur more frequently than others. However, the basis of these regularities is unknown. Some researchers have suggested that combinations such as "lbog" are rare because they require more complex articulatory gestures than combinations like "blog." Another possibility is that combinations such as "lbog" tend to be avoided because they violate much more abstract linguistic constraints on allowable syllable structures. The investigators will evaluate these possibilities by examining the role of the articulatory motor system in speech perception using both noninvasive brain stimulation and behavioral methods. Clarifying the relative contributions of speech motor processes and linguistic knowledge is critical to the diagnosis and treatment of speech language disorders, to first- and second-language acquisition, and to reading. This research explores the role of embodiment and abstraction in speech perception. It proposes that speech is represented at multiple levels (embodied phonetics and abstract phonological rules) with different susceptibility to motor simulation, depending on (a) the level of analysis and (b) a speaker's linguistic experience. The proposed experiments test this hypothesis by combining brain stimulation and behavioral experiments. Using MRI-guided Transcranial Magnetic Stimulation (TMS), the research team will disrupt activity in brain regions linked to motor action (the cortical representation of the left orbicularis oris muscle in BA4) and brain regions linked to combinatorial phonological operations (left pars triangularis, PTr, BA 45), and assess the impact on two tasks that rely differentially on phonetic processing or the putatively abstract phonological computation of syllable structure. While it is unlikely that either task or brain region is selective to a single level of analysis, these experiments gauge whether they differ in their degree of participation. If phonetic categorization requires motor simulation, then disruption of BA4 should affect phonetic categorization more than it affects the computation of syllable structure. Alternatively, if the computation of syllable structure relies on disembodied processes effected by the PTr, then the disruption of BA45 should produce a stronger effect on syllable structure than on phonetic categorization. Projects 1 and 2 examine these predictions with speakers of English and Russian (languages that contrast in their syllabic inventory). The group comparison evaluates experience-dependent plasticity or uniformity in the engagement of the motor system across tasks. Projects 3 and 4 suppress articulation mechanically. If the greater contribution of BA4 to phonetic categorization reflects its role in motor simulation, then results from disruption of the orbicularis oris muscle by TMS and mechanical suppression should converge.