Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter
Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter
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DOI：
10.1093/brain/awu390
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发表时间：
2015-03-01
期刊：
影响因子：
14.5
通讯作者：
Sommer, Martin
中科院分区：
文献类型：
--
作者：
Neef, Nicole E.;Hoang, T. N. Linh;Sommer, Martin
初级运动皮层神经元回路的精确兴奋性调节对于成功流畅地产生语音至关重要。我们的问题是，不受欢迎的运动，例如口吃，是否与初级运动皮层的口面区域的神经群的兴奋性调节不足有关。我们确定了语言相关的时间过程中的兴奋性调制的左，右初级运动舌头的代表。13名流利的演讲者（4名女性，9名男性;年龄23-44岁）和13名口吃的成年人（4名女性，9名男性，年龄21-55岁）被要求构建动词前缀为“auf”的动词。单脉冲经颅磁刺激应用于初级运动皮层之间的过渡阶段，一个固定的唇齿关节配置和以下关节配置，在不同的潜伏期后过渡发作。双侧肌电图记录从自粘电极放置在舌头表面。离线时，我们提取了运动诱发电位振幅，并将这些振幅归一化为固定配置期间的个体基线兴奋性。流利的演讲者表现出显着的左半球增加运动皮层兴奋性的过渡阶段（P = 0.009）。相反，右侧初级运动舌表征的兴奋性没有变化。有趣的是，患有口吃的成年人缺乏左半球的促进作用。此外，促进的幅度与口吃频率呈负相关。虽然口面中线肌肉双侧支配的皮质延髓的两个半球的预测，我们的研究结果表明，语音运动计划主要控制在左初级语音运动皮层。这种与语言运动规划相关的左口面运动皮层的不对称性在口吃中是缺失的。此外，促进量和口吃严重程度之间的负相关表明，我们发现了一个主要的生理原则，流利的言语生产和它的作用，口吃。
The precise excitability regulation of neuronal circuits in the primary motor cortex is central to the successful and fluent production of speech. Our question was whether the involuntary execution of undesirable movements, e.g. stuttering, is linked to an insufficient excitability tuning of neural populations in the orofacial region of the primary motor cortex. We determined the speech-related time course of excitability modulation in the left and right primary motor tongue representation. Thirteen fluent speakers (four females, nine males; aged 23-44) and 13 adults who stutter (four females, nine males, aged 21-55) were asked to build verbs with the verbal prefix 'auf'. Single-pulse transcranial magnetic stimulation was applied over the primary motor cortex during the transition phase between a fixed labiodental articulatory configuration and immediately following articulatory configurations, at different latencies after transition onset. Bilateral electromyography was recorded from self-adhesive electrodes placed on the surface of the tongue. Off-line, we extracted the motor evoked potential amplitudes and normalized these amplitudes to the individual baseline excitability during the fixed configuration. Fluent speakers demonstrated a prominent left hemisphere increase of motor cortex excitability in the transition phase (P = 0.009). In contrast, the excitability of the right primary motor tongue representation was unchanged. Interestingly, adults afflicted with stuttering revealed a lack of left-hemisphere facilitation. Moreover, the magnitude of facilitation was negatively correlated with stuttering frequency. Although orofacial midline muscles are bilaterally innervated from corticobulbar projections of both hemispheres, our results indicate that speech motor plans are controlled primarily in the left primary speech motor cortex. This speech motor planning-related asymmetry towards the left orofacial motor cortex is missing in stuttering. Moreover, a negative correlation between the amount of facilitation and stuttering severity suggests that we discovered a main physiological principle of fluent speech production and its role in stuttering.