Neural Engineering Center, Biomedical Engineering Department, Case Western Reserve University, Cleveland, OH 44106, USA.
IEEE Trans Neural Syst Rehabil Eng. 2009 Oct;17(5):461-8. doi: 10.1109/TNSRE.2009.2034072. Epub 2009 Oct 16.
The peripheral nervous system carries sensory and motor information that could be useful as command signals for function restoration in areas such as neural prosthetics and functional electrical stimulation (FES). Nerve cuff electrodes provide a robust and safe technique for recording nerve signals. However, a method to separate and recover signals from individual fascicles is necessary. Prior knowledge of the electrode geometry was used to develop an algorithm which assumes neither signal independence nor detailed knowledge of the nerve's geometry/conductivity, and is applicable to any wide-band near-field situation. When used to recover fascicular activities from simulated nerve cuff recordings in a realistic human femoral nerve model, this beamforming algorithm separates signals as close as 1.5 mm with cross-correlation coefficient, R > 0.9 (10% noise). Ten simultaneous signals could be recovered from individual fascicles with only a 20% decrease in R compared to a single signal. At high noise levels (40%), sources were localized to 180 +/- 170 microm in the 12 x 3 mm cuff. Localizing sources and using the resulting positions in the recovery algorithm yielded R = 0.66 +/- 0.10 in 10% noise for five simultaneous muscle-activation signals from synergistic fascicles. These recovered signals should allow natural, robust, closed-loop control of multiple degree-of-freedom prosthetic devices and FES systems.
周围神经系统传递感觉和运动信息，这些信息可以作为神经假肢和功能性电刺激 (FES) 等领域功能恢复的命令信号。神经袖带电极提供了一种强大而安全的记录神经信号的技术。但是，需要一种分离和恢复单个神经束信号的方法。该算法利用电极几何形状的先验知识，假设信号之间既不独立，也不需要详细了解神经的几何形状/电导率，适用于任何宽带近场情况。当该算法用于从现实人体股神经模型中的模拟神经袖带记录中恢复神经束活动时，这种波束形成算法可以将信号分离到 1.5 毫米以内，互相关系数 R > 0.9（噪声 10%）。与单个信号相比，十个同时的信号可以从单个神经束中恢复，R 值仅下降 20%。在高噪声水平（40%）下，在 12 x 3 毫米袖带中，源被定位到 180 +/- 170 微米。在噪声 10%的情况下，对于来自协同神经束的五个同时的肌肉激活信号，定位源并在恢复算法中使用所得位置可使 R = 0.66 +/- 0.10。这些恢复的信号应允许对多个自由度的假肢设备和 FES 系统进行自然、强大的闭环控制。
