研究人员发现，一种电化学方法既可局部刺激神经又可阻止电信号沿神经纤维的传播，从而将副作用最小化，新成果发表在10月在线出版的《自然—材料学》上。这种在青蛙身上获得的概念验证显示，未来有可能研制出一种可环绕神经细胞的低能、柔性的神经义肢装置。
因中风、脊柱受伤或其他神经功能失调而罹患麻痹的患者可接受功能电刺激，以激活受伤的运动神经并进行物理治疗。然而，传统的运动神经刺激方法会导致疼痛，因为所使用的电流也会影响到邻近的敏感神经细胞。Jongyoon Han和同事合作，用对钙、钾和钠离子具有选择性的外膜包裹微型电极阵列，并用这种电极在试管中对青蛙的坐骨神经的兴奋性进行调节。钙、钾和钠离子与神经冲动有关，对这些局部离子浓度进行电子调控让研究人员能够控制刺激处的神经元活性，并能按需求抑制信号的传播。此外，这种方法还能降低电化阈值、引导神经抽搐增加40%。尽管这种方法可应用于可植入神经义肢，作者指出还需要进一步的工作以证明这种方法在活体中的有效性，并将实验拓展到哺乳类动物。（生物谷 Bioon.com）
doi:10.1038/nmat3146
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Electrochemical activation and inhibition of neuromuscular systems through modulation of ion concentrations with ion-selective membranes
Yong-Ak Song,1, 2 Rohat Melik,1, 2 Amr N. Rabie,3, 4 Ahmed M. S. Ibrahim,3 David Moses,5 Ara Tan,6 Jongyoon Han1, 2 & Samuel J. Lin3
Conventional functional electrical stimulation aims to restore functional motor activity of patients with disabilities resulting from spinal cord injury or neurological disorders. However, intervention with functional electrical stimulation in neurological diseases lacks an effective implantable method that suppresses unwanted nerve signals. We have developed an electrochemical method to activate and inhibit a nerve by electrically modulating ion concentrations in situ along the nerve. Using ion-selective membranes to achieve different excitability states of the nerve, we observe either a reduction of the electrical threshold for stimulation by up to approximately 40%, or voluntary, reversible inhibition of nerve signal propagation. This low-threshold electrochemical stimulation method is applicable in current implantable neuroprosthetic devices, whereas the on-demand nerve-blocking mechanism could offer effective clinical intervention in disease states caused by uncontrolled nerve activation, such as epilepsy and chronic pain syndromes.
