Jahangiri Amir, Chau Juan M, Achanccaray David R, Sepulveda Francisco
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:2020-2023. doi: 10.1109/EMBC.2018.8512724.
In this study a single experimental protocol and analysis pipeline is used: once for MI tasks, and once for covert speech tasks. The goal of this study is not to maximizing classification accuracy; rather the main objective is to provide an identical environment for both paradigms, while identifying the most important activities related to the most class dependent features. Four volunteers participated in this experiment. With four classes, the average classification accuracy for covert speech tasks is 82.5%, and for motor imagery is 77.2%. The average performance is significantly higher than chance level for both paradigms, suggesting that the results are meaningful, despite being imperfect. For motor imagery tasks the most important activities are the execution of imagined movements, and goal driven executive control for suppression of overt movements, which also occur for covert speech tasks. However, the most important activity for covert speech tasks is the linguistic processing stages of word production prior to articulation, which does not occur in motor imagery. These high-Gamma linguistic processes are extremely class dependent, which contribute to the higher performance of covert speech tasks, compared to motor imagery in an otherwise identical environment.
在本研究中，使用了单一的实验方案和分析流程：一次用于运动想象任务，一次用于隐蔽言语任务。本研究的目标不是最大化分类准确率；相反，主要目的是为两种范式提供相同的环境，同时识别与最依赖类别特征相关的最重要活动。四名志愿者参与了该实验。对于四个类别，隐蔽言语任务的平均分类准确率为82.5%，运动想象任务的平均分类准确率为77.2%。两种范式的平均表现均显著高于随机水平，这表明尽管结果并不完美，但仍具有意义。对于运动想象任务，最重要的活动是想象动作的执行以及抑制公开动作的目标驱动执行控制，隐蔽言语任务中也会出现这些情况。然而，隐蔽言语任务最重要的活动是发音前单词生成的语言处理阶段，这在运动想象中不会出现。这些高伽马语言过程极其依赖类别，与在其他相同环境下的运动想象相比，这有助于提高隐蔽言语任务的表现。
