Department of General Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.
Neuroimage. 2010 Apr 15;50(3):1219-30. doi: 10.1016/j.neuroimage.2010.01.039. Epub 2010 Jan 18.
Clinical data indicate that the brain network of speech motor control can be subdivided into at least three functional-neuroanatomical subsystems: (i) planning of movement sequences (premotor ventrolateral-frontal cortex and/or anterior insula), (ii) preparedness for/initiation of upcoming verbal utterances (supplementary motor area, SMA), and (iii) on-line innervation of vocal tract muscles, i.e., motor execution (corticobulbar system, basal ganglia, cerebellum). Using an event-related design, this functional magnetic resonance imaging (fMRI) study sought to further delineate the contribution of SMA to pre-articulatory processes of speech production (preceding the innervation of vocal tract muscles) during an acoustically paced syllable repetition task forewarned by a tone signal. Hemodynamic activation across the whole brain and the time courses of the responses in five regions of interest (ROIs) were computed. First, motor preparation was associated with a widespread bilateral activation pattern, encompassing brainstem structures, SMA, insula, premotor ventrolateral-frontal areas, primary sensorimotor cortex (SMC), basal ganglia, and the superior cerebellum. Second, calculation of the time courses of BOLD ("blood oxygenation level-dependent") signal changes revealed the warning stimulus to elicit synchronous onset of hemodynamic activation in these areas. However, during 4-s intervals of syllable repetitions SMA and cerebellum showed opposite temporal activation patterns in terms of a shorter (SMA) and longer (cerebellum) latency of the entire BOLD response-as compared to SMC, indicating different pacing mechanisms during the initial and the ongoing phase of the task. Nevertheless, the contribution of SMA was not exclusively restricted to the preparation/initiation of verbal responses since the extension of mesiofrontal activation varied with task duration.
临床数据表明，言语运动控制的脑网络至少可以细分为三个功能神经解剖子系统：（i）运动序列的规划（前运动腹外侧额皮质和/或前岛叶），（ii）准备/启动即将到来的言语表达（辅助运动区，SMA），以及（iii）对声道肌肉的在线神经支配，即运动执行（皮质延髓系统、基底节、小脑）。本功能磁共振成像（fMRI）研究采用事件相关设计，旨在进一步描绘 SMA 在前言语产生过程中的贡献（在声道肌肉的神经支配之前），在通过音调信号预告的音节重复任务中，对语音进行声学起搏。计算了全脑的血液动力学激活和五个感兴趣区（ROI）的响应时间历程。首先，运动准备与广泛的双侧激活模式相关，包括脑干结构、SMA、岛叶、前运动腹外侧额区、初级感觉运动皮层（SMC）、基底节和上小脑。其次，计算 BOLD（“血氧水平依赖”）信号变化的时间历程表明，警告刺激会引发这些区域的血液动力学激活同步启动。然而，在音节重复的 4 秒间隔期间，SMA 和小脑在整个 BOLD 反应的潜伏期方面表现出相反的时间激活模式，即较短（SMA）和较长（小脑），表明在任务的初始和持续阶段存在不同的起搏机制。然而，SMA 的贡献不仅限于言语反应的准备/启动，因为中额叶激活的扩展随任务持续时间而变化。
