Gracco V L, Abbs J H
Speech Motor Control Laboratories, Waisman Center, University of Wisconsin, Madison.
Exp Brain Res. 1988;71(3):515-26. doi: 10.1007/BF00248744.
Previous speech kinematic studies have demonstrated systematic timing relations among the upper lip, lower lip, and jaw suggesting the operation of a central pattern generator (CPG). The present study evaluated the consistency of these timing relations following unanticipated perturbation of the lower lip. Using this approach, it was also possible to evaluate the influence of sensory information on the timing of motor output and subsequent coordination of the multiple speech movements. Perturbations were applied to the lower lip during the closing movement associated with the first "p" in "sapapple". Muscle activity and movements of the upper lip, lower lip, and jaw were obtained. Changes in movement displacement, velocity and duration, the timing and sequencing of peak velocities, EMG area, and EMG rise time were analyzed for the control and load conditions. Similar to previous perturbation results, significant magnitude compensations from the muscles and movements of the upper lip, lower lip, and jaw were observed. In contrast, movement durations and the sequencing of peak velocities were relatively unaffected by the lower lip load. The timing of peak EMG amplitude and consequently the timing of peak closing velocity for all structures (UL, LL, and J) occurred earlier relative to the preceding opening movement. These results are consistent with the interaction of phasic sensory input with centrally-driven commands resulting in a phase-advanced motor output. Further, as the timing of one structure is modified so were all the functionally-linked components thereby maintaining the necessary coordination. As in other rhythmic motor behaviors such as locomotion and chewing, there appears to be a centrally patterned framework for speech movement coordination.
先前的言语运动学研究已经证明，上唇、下唇和下颌之间存在系统的时间关系，这表明存在一个中枢模式发生器（CPG）在起作用。本研究评估了在下唇意外受到扰动后这些时间关系的一致性。通过这种方法，还能够评估感觉信息对运动输出时间以及随后多个言语动作协调的影响。在与“sapapple”中第一个“p”相关的闭合运动过程中，向下唇施加扰动。获取上唇、下唇和下颌的肌肉活动及运动情况。分析了控制条件和负载条件下运动位移、速度和持续时间的变化、峰值速度的时间和顺序、肌电图面积以及肌电图上升时间。与先前的扰动结果类似，观察到上唇、下唇和下颌的肌肉及运动有显著的幅度补偿。相比之下，运动持续时间和峰值速度的顺序相对不受下唇负载的影响。所有结构（上唇、下唇和下颌）的肌电图峰值幅度时间以及因此峰值闭合速度的时间相对于先前的张开运动发生得更早。这些结果与相位感觉输入与中枢驱动指令的相互作用一致，导致了相位提前的运动输出。此外，随着一个结构的时间被改变，所有功能相连的组件也随之改变，从而维持了必要的协调性。与其他有节奏的运动行为如行走和咀嚼一样，言语动作协调似乎存在一个中枢模式化的框架。
