Chaudhry Zahir A, Baxter Ryan H, Fu Jonathan L, Wang Po T, Sohn Won Joon, Do An H
Annu Int Conf IEEE Eng Med Biol Soc. 2024 Jul;2024:1-4. doi: 10.1109/EMBC53108.2024.10782667.
After prolonged paralysis, paraplegic spinal cord injury (SCI) patients typically lose the ability to generate the expected electroencephalogram (EEG) α/β modulation associated with leg movements. Brain computer interface (BCI)-controlled ambulation devices have emerged as a way to restore brain-controlled walking, but this loss of EEG signal modulation may impede the ability to operate such systems and prolonged training may be necessary to restore this physiologic phenomenon. To address this issue, this study explores the use of immersive virtual reality (VR) in providing more convincing feedback to enhance learning within a BCI training paradigm. Here, an EEG-based BCI-controlled walking simulator with an environment composed of 10 designated stop zones along a linear course was used to test this concept. Able-bodied subjects were tasked with using idling or kinesthetic motor imagery (KMI) of gait to control an avatar to either dwell at each designated stop for 5 s or advance along the course respectively. Subject performance was measured using a composite score per run and learning rate across runs. Composite scores were calculated as the geometric mean of two subscores: a stop score (reflecting the number of successful stops), and a time score (reflecting how fast the course was completed). The learning rate was calculated as the slope of the composite scores across all runs. A random walk procedure was performed to determine the statistical likelihood that each BCI run was purposeful (p≤ 0.001). Three able-bodied subjects were recruited (2 in immersive VR group and 1 in non-immersive VR group), and operated the simulator for up to 4 separate visits. The immersive VR group achieved an average composite score of 60.4% ± 12.9, while the non-VR group had an average composite score of 79.0% ± 12.2. The learning rate was 1.07%/run and 0.42%/run for the immersive and non-immersive VR groups, respectively. Purposeful control was attained in a higher proportion of runs for the immersive VR group than in the non-immersive VR group. Although limited by small sample size, this study demonstrates a conceptual framework of implementing immersive VR feedback using more convincing sensory feedback to aid training with BCI devices. Future work will test this protocol in SCI patients and with larger sample size.
在长期瘫痪后，截瘫脊髓损伤（SCI）患者通常会失去产生与腿部运动相关的预期脑电图（EEG）α/β调制的能力。脑机接口（BCI）控制的行走装置已成为恢复脑控行走的一种方式，但这种EEG信号调制的丧失可能会阻碍操作此类系统的能力，可能需要长时间训练来恢复这种生理现象。为了解决这个问题，本研究探索使用沉浸式虚拟现实（VR）来提供更有说服力的反馈，以增强BCI训练范式中的学习效果。在此，使用一个基于EEG的BCI控制的行走模拟器，其环境由沿着直线路线的10个指定停车区组成，来测试这一概念。健全受试者的任务是使用步态的闲置或动觉运动想象（KMI）来控制虚拟化身，使其分别在每个指定停车区停留5秒或沿着路线前进。使用每次运行的综合得分和各次运行的学习率来衡量受试者的表现。综合得分计算为两个子得分的几何平均值：停车得分（反映成功停车的次数）和时间得分（反映完成路线的速度）。学习率计算为所有运行中综合得分的斜率。执行随机游走程序以确定每次BCI运行是有目的的统计可能性（p≤0.001）。招募了三名健全受试者（沉浸式VR组2名，非沉浸式VR组1名），并让他们操作模拟器进行多达4次单独访问。沉浸式VR组的平均综合得分为60.4%±12.9，而非VR组的平均综合得分为79.0%±12.2。沉浸式和非沉浸式VR组的学习率分别为1.07%/次运行和0.42%/次运行。与非沉浸式VR组相比，沉浸式VR组在更高比例的运行中实现了有目的的控制。尽管受样本量小的限制，但本研究展示了一个概念框架，即使用更有说服力的感官反馈来实施沉浸式VR反馈，以辅助BCI设备的训练。未来的工作将在SCI患者中并以更大的样本量测试该方案。
