Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
Sci Rep. 2022 Nov 28;12(1):20467. doi: 10.1038/s41598-022-24368-2.
Touch-like phantom limb sensations can be elicited through targeted transcutaneous electrical nerve stimulation (tTENS) in individuals with upper limb amputation. The corresponding impact of sensory stimulation on cortical activity remains an open question. Brain network research shows that sensorimotor cortical activity is supported by dynamic changes in functional connections between relevant brain regions. These groups of interconnected regions are functional modules whose architecture enables specialized function and related neural processing supporting individual task needs. Using electroencephalographic (EEG) signals to analyze modular functional connectivity, we investigated changes in the modular architecture of cortical large-scale systems when participants with upper limb amputations performed phantom hand movements before, during, and after they received tTENS. We discovered that tTENS substantially decreased the flexibility of the default mode network (DMN). Furthermore, we found increased interconnectivity (measured by a graph theoretic integration metric) between the DMN, the somatomotor network (SMN) and the visual network (VN) in the individual with extensive tTENS experience. While for individuals with less tTENS experience, we found increased integration between DMN and the attention network. Our results provide insights into how sensory stimulation promotes cortical processing of combined somatosensory and visual inputs and help develop future tools to evaluate sensory combination for individuals with amputations.
通过针对上肢截肢患者的经皮神经电刺激（tTENS），可以诱发类似触摸的幻肢感觉。感觉刺激对皮质活动的相应影响仍然是一个悬而未决的问题。脑网络研究表明，感觉运动皮质活动由相关脑区之间功能连接的动态变化所支持。这些相互关联的区域群是功能模块，其架构能够实现专门的功能和相关的神经处理，以支持个体任务的需求。我们使用脑电图（EEG）信号来分析皮质大尺度系统的模块功能连接，研究了上肢截肢患者在接受 tTENS 前后进行幻手运动时，皮质大尺度系统模块结构的变化。我们发现 tTENS 显著降低了默认模式网络（DMN）的灵活性。此外，我们发现具有广泛 tTENS 经验的个体中，DMN 与躯体运动网络（SMN）和视觉网络（VN）之间的连通性增加（通过图论整合度量来衡量）。而对于 tTENS 经验较少的个体，我们发现 DMN 与注意网络之间的整合增加。我们的研究结果提供了有关感觉刺激如何促进联合躯体感觉和视觉输入的皮质处理的见解，并有助于开发未来的工具来评估截肢患者的感觉组合。
