Yan Yan, Lu Yiliang, Li Menghui, Ma Zengguang, Cao Pengjia, Chen Yao, Sun Xiaodong, Chai Xinyu, Ren Qiushi, Li Liming
School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Invest Ophthalmol Vis Sci. 2016 Nov 1;57(14):6327-6338. doi: 10.1167/iovs.15-17543.
Current steering is a neural stimulation strategy that uses simultaneous stimulation of adjacent electrodes to produce additional intermediate stimulation sites and thus improves spatial resolution. We investigated the feasibility of current steering using electrophysiological and computational methods after implanting paired penetrating electrodes into the rabbit's optic nerve (ON).
Penetrating electrodes at different interelectrode distances were implanted into the ON and electrically evoked cortical potentials (EEPs) in V1 recorded with a 6 × 8 array. The current thresholds, EEP amplitudes, and spatial distributions were analyzed during current steering. Computational simulation studies were performed based on finite element models to calculate the area and spatial distribution of recruited ON fibers using a current steering stimulation strategy.
Threshold reduction and EEP amplitude enhancement were found with simultaneous stimulation of closely spaced electrode pairs. Spatially shifted cortical responses were achieved using current steering, whereas the amplitudes and spatial spreads of the responses were similar to that elicited by a single electrode. Computational simulations suggested that the centroid of the ON recruitment area could be modulated by current steering while the total recruitment area did not show any appreciable variability at a fixed current intensity.
Current steering is a useful strategy to enhance the spatial resolution of an ON prosthesis without increasing the number of physical electrodes. This study provides useful information for optimizing the design of stimulation strategies with a penetrating ON prosthesis.
电流转向是一种神经刺激策略，它通过同时刺激相邻电极来产生额外的中间刺激位点，从而提高空间分辨率。我们在将成对的穿透性电极植入兔视神经（ON）后，使用电生理和计算方法研究了电流转向的可行性。
将不同电极间距的穿透性电极植入视神经，并使用6×8阵列记录V1区的电诱发皮层电位（EEP）。在电流转向过程中分析电流阈值、EEP幅度和空间分布。基于有限元模型进行计算模拟研究，以使用电流转向刺激策略计算募集的视神经纤维的面积和空间分布。
同时刺激间距紧密的电极对时，发现阈值降低和EEP幅度增强。使用电流转向可实现皮层反应的空间移位，而反应的幅度和空间扩散与单个电极引发的相似。计算模拟表明，在固定电流强度下，电流转向可调节视神经募集区域的质心，而总募集区域没有显示出任何明显变化。
电流转向是一种在不增加物理电极数量的情况下提高视神经假体空间分辨率的有用策略。本研究为优化穿透性视神经假体的刺激策略设计提供了有用信息。
