Laboratory for Non-Invasive Brain Machine Interface Systems, NSF IUCRC BRAIN, University of Houston, Houston, TX, 77004, United States of America.
Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, 77030, United States of America.
J Neural Eng. 2022 Jul 1;19(4). doi: 10.1088/1741-2552/ac7b4b.
Transcutaneous spinal cord stimulation (TSS) has been shown to be a promising non-invasive alternative to epidural spinal cord stimulation for improving outcomes of people with spinal cord injury (SCI). However, studies on the effects of TSS on cortical activation are limited. Our objectives were to evaluate the spatiotemporal effects of TSS on brain activity, and determine changes in functional connectivity under several different stimulation conditions. As a control, we also assessed the effects of functional electrical stimulation (FES) on cortical activity.. Non-invasive scalp electroencephalography (EEG) was recorded during TSS or FES while five neurologically intact participants performed one of three lower-limb tasks while in the supine position: (1) A no contraction control task, (2) a rhythmic contraction task, or (3) a tonic contraction task. After EEG denoising and segmentation, independent components (ICs) were clustered across subjects to characterize sensorimotor networks in the time and frequency domains. ICs of the event related potentials (ERPs) were calculated for each cluster and condition. Next, a Generalized Partial Directed Coherence (gPDC) analysis was performed on each cluster to compare the functional connectivity between conditions and tasks.. IC analysis of EEG during TSS resulted in three clusters identified at Brodmann areas (BA) 9, BA 6, and BA 4, which are areas associated with working memory, planning, and movement control. Lastly, we found significant ( < 0.05, adjusted for multiple comparisons) increases and decreases in functional connectivity of clusters during TSS, but not during FES when compared to the no stimulation conditions.The findings from this study provide evidence of how TSS recruits cortical networks during tonic and rhythmic lower limb movements. These results have implications for the development of spinal cord-based computer interfaces, and the design of neural stimulation devices for the treatment of pain and sensorimotor deficit.
经皮脊髓电刺激（TSS）已被证明是一种有前途的非侵入性替代方法，可以改善脊髓损伤（SCI）患者的预后。然而，关于 TSS 对皮质激活影响的研究有限。我们的目的是评估 TSS 对大脑活动的时空影响，并确定在几种不同刺激条件下功能连接的变化。作为对照，我们还评估了功能性电刺激（FES）对皮质活动的影响。在 TSS 或 FES 期间，通过非侵入性头皮脑电图（EEG）记录，同时 5 名神经完整的参与者在仰卧位时进行三种下肢任务中的一种：（1）无收缩对照任务，（2）节律性收缩任务，或（3）强直性收缩任务。在 EEG 去噪和分段后，通过对受试者进行聚类来确定时间和频率域中的感觉运动网络。为每个集群和条件计算事件相关电位（ERP）的独立成分（IC）。接下来，对每个集群进行广义部分定向相干性（gPDC）分析，以比较条件和任务之间的功能连接。TSS 期间 EEG 的 IC 分析导致在布罗德曼区域（BA）9、BA 6 和 BA 4 处识别出三个集群，这些区域与工作记忆、计划和运动控制有关。最后，我们发现 TSS 期间集群的功能连接显著增加和减少（ < 0.05，经多重比较调整），但在 FES 期间与无刺激条件相比则没有。本研究的结果提供了 TSS 在强直性和节律性下肢运动期间募集皮质网络的证据。这些结果对于基于脊髓的计算机接口的开发以及用于治疗疼痛和感觉运动缺陷的神经刺激设备的设计具有重要意义。
