Lim Jeffrey, Wang Po T, Bidhendi Alireza K, Arasteh Omid M, Shaw Susan J, Armacost Michelle, Gong Hui, Liu Charles Y, Heydari Payam, Do An H, Nenadic Zoran
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:4748-4751. doi: 10.1109/EMBC.2018.8513216.
Bi-directional brain-computer interfaces (BCIs) require simultaneous stimulation and recording to achieve closed-loop operation. It is therefore important that the interface be able to distinguish between neural signals of interest and stimulation artifacts. Current bi-directional BCIs address this problem by temporally multiplexing stimulation and recording. This approach, however, is suboptimal in many BCI applications. Alternative artifact mitigation methods can be devised by investigating the mechanics of artifact propagation. To characterize stimulation artifact behaviors, we collected and analyzed electrocorticography (ECoG) data from eloquent cortex mapping. Ratcheting and phase-locking of stimulation artifacts were observed, as well as dipole-like properties. Artifacts as large as ±1,100 μV appeared as far as 15-37 mm away from the stimulating channel when stimulating at 10 mA. Analysis also showed that the majority of the artifact power was concentrated at the stimulation pulse train frequency (50 Hz) and its super-harmonics (100, 150, 200 Hz). Lower frequencies (0-32 Hz) experienced minimal artifact contamination. These findings could inform the design of future bi-directional ECoG-based BCIs.
双向脑机接口(BCI)需要同时进行刺激和记录以实现闭环操作。因此,接口能够区分感兴趣的神经信号和刺激伪迹非常重要。当前的双向BCI通过时间复用刺激和记录来解决这个问题。然而,这种方法在许多BCI应用中并非最优。可以通过研究伪迹传播机制来设计替代的伪迹减轻方法。为了表征刺激伪迹行为,我们收集并分析了来自明确皮层映射的脑电皮层图(ECoG)数据。观察到了刺激伪迹的棘轮效应和锁相现象,以及偶极子样特性。当以10 mA进行刺激时,在距离刺激通道15 - 37 mm处出现了高达±1,100 μV的伪迹。分析还表明,大部分伪迹功率集中在刺激脉冲串频率(50 Hz)及其超谐波(100、150、200 Hz)上。较低频率(0 - 32 Hz)受到的伪迹污染最小。这些发现可为未来基于ECoG的双向BCI设计提供参考。