Department of Neurosurgery, The ClevelandClinic, Lerner Research Institute, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Neurosurg Focus. 2013 Jun;34(6):E3. doi: 10.3171/2013.3.FOCUS1373.
Stereoelectroencephalography (SEEG) is becoming more prevalent as a planning tool for surgical treatment of intractable epilepsy. Stereoelectroencephalography uses long, thin, cylindrical "depth" electrodes containing multiple recording contacts along each electrode's length. Each lead is inserted into the brain percutaneously. The advantage of SEEG is that the electrodes can easily target deeper brain structures that are inaccessible with subdural grid electrodes, and SEEG does not require a craniotomy. Brain-machine interface (BMI) research is also becoming more common in the Epilepsy Monitoring Unit. A brain-machine interface decodes a person's desired movement or action from the recorded brain activity and then uses the decoded brain activity to control an assistive device in real time. Although BMIs are primarily being developed for use by severely paralyzed individuals, epilepsy patients undergoing invasive brain monitoring provide an opportunity to test the effectiveness of different invasive recording electrodes for use in BMI systems. This study investigated the ability to use SEEG electrodes for control of 2D cursor velocity in a BMI. Two patients who were undergoing SEEG for intractable epilepsy participated in this study. Participants were instructed to wiggle or rest the hand contralateral to their SEEG electrodes to control the horizontal velocity of a cursor on a screen. Simultaneously they were instructed to wiggle or rest their feet to control the vertical component of cursor velocity. The BMI system was designed to detect power spectral changes associated with hand and foot activity and translate those spectral changes into horizontal and vertical cursor movements in real time. During testing, participants used their decoded SEEG signals to move the brain-controlled cursor to radial targets that appeared on the screen. Although power spectral information from 28 to 32 electrode contacts were used for cursor control during the experiment, post hoc analysis indicated that better control may have been possible using only a single SEEG depth electrode containing multiple recording contacts in both hand and foot cortical areas. These results suggest that the advantages of using SEEG for epilepsy monitoring may also apply to using SEEG electrodes in BMI systems. Specifically, SEEG electrodes can target deeper brain structures, such as foot motor cortex, and both hand and foot areas can be targeted with a single SEEG electrode implanted percutaneously. Therefore, SEEG electrodes may be an attractive option for simple BMI systems that use power spectral modulation in hand and foot cortex for independent control of 2 degrees of freedom.
立体脑电图（SEEG）作为一种治疗难治性癫痫的手术规划工具，越来越受到关注。立体脑电图使用细长的圆柱形“深度”电极，每个电极的长度上都有多个记录触点。每个导联经皮插入大脑。SEEG 的优势在于电极可以轻松地瞄准深部脑结构，这些结构是硬膜下网格电极无法到达的，而且 SEEG 不需要开颅手术。脑机接口（BMI）研究在癫痫监测单元中也越来越普遍。脑机接口从记录的大脑活动中解码出一个人想要的运动或动作，然后使用解码后的大脑活动实时控制辅助设备。尽管 BMI 主要是为严重瘫痪的人开发的，但接受侵入性脑监测的癫痫患者为测试不同的侵入性记录电极在 BMI 系统中的有效性提供了机会。这项研究调查了使用 SEEG 电极控制 BMI 中二维光标速度的能力。两名因难治性癫痫而接受 SEEG 监测的患者参与了这项研究。参与者被指示晃动或休息与 SEEG 电极相对的手来控制屏幕上光标的水平速度。同时，他们被指示晃动或休息他们的脚来控制光标速度的垂直分量。BMI 系统旨在检测与手和脚活动相关的功率谱变化，并实时将这些谱变化转换为光标水平和垂直运动。在测试过程中，参与者使用解码后的 SEEG 信号将大脑控制的光标移动到屏幕上出现的径向目标。尽管在实验过程中使用了 28 到 32 个电极触点的功率谱信息来控制光标，但事后分析表明，仅使用单个 SEEG 深度电极，该电极在手部和脚部皮质区域包含多个记录触点，可能会有更好的控制效果。这些结果表明，使用 SEEG 进行癫痫监测的优势也可能适用于 BMI 系统中使用 SEEG 电极。具体来说，SEEG 电极可以瞄准深部脑结构，如脚部运动皮质，并且可以使用单个经皮植入的 SEEG 电极同时瞄准手部和脚部区域。因此，对于使用手部和脚部皮质的功率谱调制进行独立控制的简单 BMI 系统，SEEG 电极可能是一个有吸引力的选择。
