Educational Neuroscience Program, Gallaudet University, Washington, DC, USA.
Educational Neuroscience Program, Gallaudet University, Washington, DC, USA; Department of Psychology, Gallaudet University, Washington, DC, USA.
Cortex. 2019 Oct;119:457-469. doi: 10.1016/j.cortex.2019.07.016. Epub 2019 Aug 9.
When a person observes someone else performing an action, the observer's sensorimotor cortex activates as if the observer is the one performing the action, a phenomenon known as action simulation. While this process has been well-established for basic (e.g., grasping) and complex (e.g., dancing) actions, it remains unknown if the framework of action simulation is applicable to visual languages such as American Sign Language (ASL). We conducted an EEG experiment with deaf signers and hearing non-signers to compare overall sensorimotor EEG between groups, and to test whether sensorimotor systems are differentially sensitive to signs that are produced with one hand ("1H") or two hands ("2H"). We predicted greater alpha and beta event-related desynchronization (previously correlated with action simulation) during the perception of 2H ASL signs compared to 1H ASL signs, due to greater demands on sensorimotor processing systems required for producing two-handed actions. We recorded EEG from both groups as they observed videos of ASL signs, half 1H and half 2H. Event-related spectral perturbations (ERSPs) in the alpha and beta ranges were computed for the two conditions at central electrode sites overlying the sensorimotor cortex. Sensorimotor EEG responses in both Hearing and Deaf groups were sensitive to the observed gross motor characteristics of the observed signs. We show for the first time that despite hearing non-signers showing overall more sensorimotor cortex involvement during sign observation, mirroring-related processes are in fact involved when deaf signers observe signs.
当一个人观察别人执行某个动作时，观察者的运动感觉皮层会像自己在执行该动作一样被激活，这种现象被称为动作模拟。虽然这个过程已经在基本动作（例如抓握）和复杂动作（例如跳舞）中得到了很好的证实，但目前尚不清楚动作模拟的框架是否适用于视觉语言，例如美国手语（ASL）。我们对聋人手语者和听力非手语者进行了 EEG 实验，以比较组间整体运动感觉 EEG，并测试运动感觉系统是否对手语者用单手（“1H”）或双手（“2H”）产生的手语符号有不同的敏感性。我们预测，由于产生双手动作需要更高的运动感觉处理系统要求，与单手产生的 ASL 符号相比，在感知 2H ASL 符号时，会出现更大的 alpha 和 beta 事件相关去同步化（先前与动作模拟相关）。我们让两组人员在观察 ASL 符号的视频时记录 EEG，一半是 1H，一半是 2H。在中央电极位置，对运动感觉皮层上的两种条件计算 alpha 和 beta 范围内的事件相关频谱扰动（ERSPs）。听力和聋人组的运动感觉 EEG 反应都对观察到的符号的明显总体运动特征敏感。我们首次表明，尽管听力非手语者在观察手语时表现出整体更多的运动感觉皮层参与，但聋人手语者在观察手语时实际上涉及到镜像相关过程。
