Bose Rohit, Ding Keqin, Seet Manuel, Osborn Luke, Bezerianos Anastasios, Thakor Nitish, Dragomir Andrei
Annu Int Conf IEEE Eng Med Biol Soc. 2020 Jul;2020:3844-3847. doi: 10.1109/EMBC44109.2020.9175224.
Sensory feedback in upper limb amputees is crucial for improving movement decoding and also to enhance embodiment of the prosthetic limb. Recently, an increasing number of invasive and noninvasive solutions for sensory stimulation have demonstrated the capability of providing a range of sensations to upper limb amputees. However, the cortical impact of restored sensation is not clearly understood. Particularly, understanding the cortical connectivity changes at multiple scales (nodal and modular) in response to sensory stimulation, can reveal crucial information on how amputees brain process the sensory stimuli. Using Electroencephalography (EEG) signals, we compared the cortical connectivity network in response to sensory feedback provided by targeted transcutaneous electrical nerve stimulation (tTENS) in an upper limb amputee during phantom upper limb movements. We focused our cortical connectivity analysis on four functional modules comprising of 20 brain regions that are primarily associated with a visually guided motor task (visual, motor, somatosensory and multisensory integration (MI)) used in this study. At the modular level, we observed that the hubness (a graph theoretic measure quantifying the importance of brain regions in integrating brain function) of the motor module decreases whereas that of the somatosensory module increases in presence of tTENS feedback. At the nodal level, similar observations were made for the visual and MI regions. This is the first work to reveal the impact of sensory feedback at multiple scales in the cortex of amputees in response to sensory stimulation.
上肢截肢者的感觉反馈对于改善运动解码以及增强假肢的融入感至关重要。最近，越来越多的侵入性和非侵入性感觉刺激解决方案已证明能够为上肢截肢者提供一系列感觉。然而，恢复感觉对皮层的影响尚不清楚。特别是，了解响应感觉刺激时多尺度（节点和模块）的皮层连接变化，可以揭示截肢者大脑如何处理感觉刺激的关键信息。我们使用脑电图（EEG）信号，比较了一名上肢截肢者在幻肢运动期间，针对经皮神经电刺激（tTENS）提供的感觉反馈的皮层连接网络。我们将皮层连接分析重点放在四个功能模块上，这些模块由20个主要与本研究中使用的视觉引导运动任务（视觉、运动、体感和多感觉整合（MI））相关的脑区组成。在模块水平上，我们观察到在tTENS反馈存在的情况下，运动模块的中心性（一种量化脑区在整合脑功能中重要性的图论度量）降低，而体感模块的中心性增加。在节点水平上，对视觉和MI区域也有类似的观察结果。这是第一项揭示截肢者皮层在响应感觉刺激时多尺度感觉反馈影响的研究。
