Johari Karim, Behroozmand Roozbeh
Speech Neuroscience Lab, Department of Communication Sciences and Disorders, University of South Carolina, 1224 Sumter Street, Columbia, SC 29201, United States.
Speech Neuroscience Lab, Department of Communication Sciences and Disorders, University of South Carolina, 1224 Sumter Street, Columbia, SC 29201, United States.
Hum Mov Sci. 2017 Aug;54:41-50. doi: 10.1016/j.humov.2017.03.005. Epub 2017 Apr 2.
Skilled movement is mediated by motor commands executed with extremely fine temporal precision. The question of how the brain incorporates temporal information to perform motor actions has remained unanswered. This study investigated the effect of stimulus temporal predictability on response timing of speech and hand movement. Subjects performed a randomized vowel vocalization or button press task in two counterbalanced blocks in response to temporally-predictable and unpredictable visual cues. Results indicated that speech and hand reaction time was decreased for predictable compared with unpredictable stimuli. This finding suggests that a temporal predictive code is established to capture temporal dynamics of sensory cues in order to produce faster movements in responses to predictable stimuli. In addition, results revealed a main effect of modality, indicating faster hand movement compared with speech. We suggest that this effect is accounted for by the inherent complexity of speech production compared with hand movement. Lastly, we found that movement inhibition was faster than initiation for both hand and speech, suggesting that movement initiation requires a longer processing time to coordinate activities across multiple regions in the brain. These findings provide new insights into the mechanisms of temporal information processing during initiation and inhibition of speech and hand movement.
熟练的动作是由以极高时间精度执行的运动指令介导的。大脑如何整合时间信息以执行运动动作的问题一直未得到解答。本研究调查了刺激时间可预测性对言语和手部动作反应时间的影响。受试者在两个平衡的组块中执行随机的元音发声或按键任务，以响应时间上可预测和不可预测的视觉线索。结果表明，与不可预测的刺激相比，可预测刺激的言语和手部反应时间缩短。这一发现表明，建立了一种时间预测编码来捕捉感觉线索的时间动态，以便在对可预测刺激的反应中产生更快的动作。此外，结果揭示了模态的主效应，表明手部动作比言语动作更快。我们认为，这种效应是由言语产生与手部动作相比固有的复杂性所导致的。最后，我们发现手部和言语动作的抑制都比启动更快，这表明动作启动需要更长的处理时间来协调大脑多个区域的活动。这些发现为言语和手部动作启动与抑制过程中的时间信息处理机制提供了新的见解。
