Agashe Harshavardhan A, Paek Andrew Y, Zhang Yuhang, Contreras-Vidal José L
Noninvasive Brain-Machine Interface Systems Lab, Electrical and Computer Engineering, University of Houston Houston, TX, USA.
Noninvasive Brain-Machine Interface Systems Lab, Electrical and Computer Engineering, University of Houston Houston, TX, USA ; Hyperspectral Image Analysis Lab, Department of Electrical and Computer Engineering, University of Houston Houston, TX, USA.
Front Neurosci. 2015 Apr 9;9:121. doi: 10.3389/fnins.2015.00121. eCollection 2015.
Recent studies show that the amplitude of cortical field potentials is modulated in the time domain by grasping kinematics. However, it is unknown if these low frequency modulations persist and contain enough information to decode grasp kinematics in macro-scale activity measured at the scalp via electroencephalography (EEG). Further, it is unclear as to whether joint angle velocities or movement synergies are the optimal kinematics spaces to decode. In this offline decoding study, we infer from human EEG, hand joint angular velocities as well as synergistic trajectories as subjects perform natural reach-to-grasp movements. Decoding accuracy, measured as the correlation coefficient (r) between the predicted and actual movement kinematics, was r = 0.49 ± 0.02 across 15 hand joints. Across the first three kinematic synergies, decoding accuracies were r = 0.59 ± 0.04, 0.47 ± 0.06, and 0.32 ± 0.05. The spatial-temporal pattern of EEG channel recruitment showed early involvement of contralateral frontal-central scalp areas followed by later activation of central electrodes over primary sensorimotor cortical areas. Information content in EEG about the grasp type peaked at 250 ms after movement onset. The high decoding accuracies in this study are significant not only as evidence for time-domain modulation in macro-scale brain activity, but for the field of brain-machine interfaces as well. Our decoding strategy, which harnesses the neural "symphony" as opposed to local members of the neural ensemble (as in intracranial approaches), may provide a means of extracting information about motor intent for grasping without the need for penetrating electrodes and suggests that it may be soon possible to develop non-invasive neural interfaces for the control of prosthetic limbs.
最近的研究表明,皮质场电位的幅度在时域中会受到抓握运动学的调制。然而,尚不清楚这些低频调制是否持续存在,以及是否包含足够的信息来通过脑电图(EEG)在头皮测量的宏观尺度活动中解码抓握运动学。此外,尚不清楚关节角速度或运动协同效应是否是用于解码的最佳运动学空间。在这项离线解码研究中,我们在受试者进行自然伸手抓握运动时,从人类脑电图、手部关节角速度以及协同轨迹中进行推断。以预测运动学与实际运动学之间的相关系数(r)衡量的解码准确率,在15个手部关节上为r = 0.49±0.02。在前三个运动协同效应中,解码准确率分别为r = 0.59±0.04、0.47±0.06和0.32±0.05。脑电图通道募集的时空模式显示,对侧额中央头皮区域早期参与,随后初级感觉运动皮层区域的中央电极被激活。脑电图中关于抓握类型的信息含量在运动开始后250毫秒达到峰值。本研究中的高解码准确率不仅作为宏观尺度大脑活动中时域调制的证据具有重要意义,对于脑机接口领域也是如此。我们的解码策略利用神经“交响乐”,而不是神经集合的局部成员(如颅内方法那样),可能提供一种无需穿透电极就能提取关于抓握运动意图信息的方法,并表明可能很快就能开发出用于控制假肢的非侵入性神经接口。