Speech Neuroscience Lab, Department of Communication Sciences and Disorders, University of South Carolina, 915 Greene Street, Columbia, SC, 29208, USA.
Neurolinguistics Lab, Department of Communication Sciences and Disorders, University of South Carolina, 915 Greene St, Columbia, SC, 29208, USA.
Exp Brain Res. 2019 Jul;237(7):1759-1772. doi: 10.1007/s00221-019-05549-4. Epub 2019 Apr 27.
Normal aging is associated with decline of the sensorimotor mechanisms that support movement function in the human brain. In this study, we used behavioral and event-related potential (ERP) recordings to investigate the effects of normal aging on the motor preparatory mechanisms of speech production and limb movement. The experiment involved two groups of older and younger adults who performed randomized speech vowel vocalization and button press motor reaction time tasks in response to temporally predictable and unpredictable visual stimuli. Behavioral results revealed age-related slowness of motor reaction time only during speech production in response to temporally unpredictable stimuli, and this effect was accompanied by increased pre-motor ERP activities in older vs. younger adults during the speech task. These results indicate that motor preparatory mechanisms of limb movement during button press are not affected by normal aging, whereas the functional capacity of these mechanisms is reduced in older adults during speech production in response to unpredictable sensory stimuli. These findings suggest that the aging brain selectively compromises the motor timing of speech and recruits additional neural resources for motor planning and execution of speech, as indexed by the increased pre-motor ERP activations in response to temporally unpredictable vs. predictable sensory stimuli.
正常衰老与支持人类大脑运动功能的感觉运动机制的衰退有关。在这项研究中，我们使用行为和事件相关电位（ERP）记录来研究正常衰老对言语产生和肢体运动的运动准备机制的影响。实验涉及两组年龄较大和较小的成年人，他们根据时间上可预测和不可预测的视觉刺激随机进行言语元音发声和按钮按下运动反应时间任务。行为结果表明，只有在对时间不可预测的刺激做出言语反应时，年龄与运动反应时间的减慢有关，而在言语任务中，与年轻成年人相比，老年人的运动前 ERP 活动增加。这些结果表明，在按钮按下期间，肢体运动的运动准备机制不受正常衰老的影响，而在对不可预测的感觉刺激做出言语反应时，这些机制的功能能力在老年人中降低。这些发现表明，衰老的大脑选择性地损害言语的运动定时，并为言语的运动规划和执行招募额外的神经资源，这可以通过对时间不可预测与可预测的感觉刺激的运动前 ERP 激活增加来表示。
