Fox P T, Ingham R J, Ingham J C, Hirsch T B, Downs J H, Martin C, Jerabek P, Glass T, Lancaster J L
Research Imaging Center and Department of Radiology, University of Texas Health Science Center at San Antonio 78284, USA.
Nature. 1996 Jul 11;382(6587):158-61. doi: 10.1038/382158a0.
The cause of stuttering is unknown. Failure to develop left-hemispheric dominance for speech is a long-standing theory although others implicated the motor system more broadly, often postulating hyperactivity of the right (language nondominant) cerebral hemisphere. As knowledge of motor circuitry has advanced, theories of stuttering have become more anatomically specific, postulating hyperactivity of premotor cortex, either directly or through connectivity with the thalamus and basal ganglia. Alternative theories target the auditory and speech production systems. By contrasting stuttering with fluent speech using positron emission tomography combined with chorus reading to induce fluency, we found support for each of these hypotheses. Stuttering induced widespread overactivations of the motor system in both cerebrum and cerebellum, with right cerebral dominance. Stuttered reading lacked left-lateralized activations of the auditory system, which are thought to support the self-monitoring of speech, and selectively deactivated a frontal-temporal system implicated in speech production. Induced fluency decreased or eliminated the overactivity in most motor areas, and largely reversed the auditory-system underactivations and the deactivation of the speech production system. Thus stuttering is a disorder affecting the multiple neural systems used for speaking.
口吃的病因尚不清楚。未能形成左半球对言语的优势是一个长期存在的理论，尽管其他理论更广泛地涉及运动系统，通常假定右（非语言优势）大脑半球活动亢进。随着对运动回路知识的进步，口吃理论在解剖学上变得更加具体，假定运动前皮层活动亢进，要么直接亢进，要么通过与丘脑和基底神经节的连接而亢进。其他理论则针对听觉和言语产生系统。通过使用正电子发射断层扫描结合齐声朗读以诱导流畅性，将口吃与流畅言语进行对比，我们发现这些假设都得到了支持。口吃在大脑和小脑中均引起运动系统广泛的过度激活，以右脑为主导。口吃朗读缺乏听觉系统的左侧化激活，而这种激活被认为有助于言语的自我监测，并且选择性地使与言语产生相关的额颞系统失活。诱导的流畅性降低或消除了大多数运动区域的过度活动，并在很大程度上逆转了听觉系统的活动不足以及言语产生系统的失活。因此，口吃是一种影响用于说话的多个神经系统的障碍。
