神经电信号中眼轮匝肌功能状态的识别

目的:提取能反映眼轮匝肌功能活动的狗面神经颧支的神经电信号(ENG),通过对ENG信号的分析,识别出眼轮匝肌的功能状态。方法:利用植入到狗面神经颧支周围的Cuff电极提取有闭眼动作发生期间的神经电信号,采用幅度阈值法,通过对ENG信号的分析,识别出闭眼动作发生时眼轮匝肌的收缩动作。结果:研究中我们提取到了能反映闭眼动作发生的ENG信号,并且通过对信号的分析,识别出了眼轮匝肌收缩动作的发生。结论:可以通过对眼轮匝肌支配神经上ENG信号的分析,监控眼轮匝肌的功能状态。     

基于ANSYS/LS-DYNA的神经电极植入脑组织过程数值仿真

目的建立神经电极-脑组织数值仿真模型,研究神经电极在植入过程中对脑组织产生的植入损伤。方法采用超黏弹性模型描述脑组织材料,基于单元删除法和最大主应变失效准则模拟组织破坏与分离,并通过平均等效应变量化组织植入损伤,考察神经电极楔形角、植入速度以及电极刚度对脑组织急性损伤的影响规律。结果150°楔角所产生应变值较90°增加37.1%;100μm/s慢速植入时电极植入路径上组织应变值较大(57%),500μm/s较高速植入时植入路径上组织应变明显变小(25%);而电极刚度对组织损伤影响不明显,电极刚度从165 GPa下降至5 k Pa时,组织应变仅增加1%~2%。结论数值仿真模型可为神经电极与植入参数设计提供参考,从而减少组织植入损伤,提高电极工作寿命,满足长期临床应用。     

基于ANSYS/LS-DYNA的神经电极植入脑组织过程数值仿真

目的 建立神经电极-脑组织数值仿真模型,研究神经电极在植入过程中对脑组织产生的植入损伤。方法 采用超黏弹性模型描述脑组织材料,基于单元删除法和最大主应变失效准则模拟组织破坏与分离,并通过平均等效应变量化组织植入损伤,考察神经电极楔形角、植入速度以及电极刚度对脑组织急性损伤的影响规律。结果 150°楔角所产生应变值较90°增加37.1%;100 μm/s慢速植入时电极植入路径上组织应变值较大（>57%）,500 μm/s较高速植入时植入路径上组织应变明显变小（<25%）;而电极刚度对组织损伤影响不明显,电极刚度从165 GPa下降至5 kPa时,组织应变仅增加1%~2%。结论 数值仿真模型可为神经电极与植入参数设计提供参考,从而减少组织植入损伤,提高电极工作寿命,满足长期临床应用。     

基于ANSYS/LS-DYNA的神经电极植入脑组织过程数值仿真

目的 建立神经电极-脑组织数值仿真模型,研究神经电极在植入过程中对脑组织产生的植入损伤。方法 采用超黏弹性模型描述脑组织材料,基于单元删除法和最大主应变失效准则模拟组织破坏与分离,并通过平均等效应变量化组织植入损伤,考察神经电极楔形角、植入速度以及电极刚度对脑组织急性损伤的影响规律。结果 150°楔角所产生应变值较90°增加37.1%;100 μm/s慢速植入时电极植入路径上组织应变值较大（>57%）,500 μm/s较高速植入时植入路径上组织应变明显变小（<25%）;而电极刚度对组织损伤影响不明显,电极刚度从165 GPa下降至5 kPa时,组织应变仅增加1%~2%。结论 数值仿真模型可为神经电极与植入参数设计提供参考,从而减少组织植入损伤,提高电极工作寿命,满足长期临床应用。     

利用AR模型参数分析损伤神经的针电极肌电信号

影响募集形式的两种主要因素为时间募集和空间募集 ,本文提出了一种利用现代谱分析技术来分析针电极肌电信号募集的方法。通过建立全极点 AR模型 ,利用时 -频谱分析了不同神经不同程度损伤的肌电信号的时间募集减少和空间募集减少。最后提取前臂 NEMG信号的 AR系数并通过 BP神经网络辨识了不同程度损伤的肌电信号 ,取得了良好的实验结果。     

神经信号经皮传输的电路设计与仿真实验

本研究旨在实现利用神经动作电信号控制多自由度假肢。针对植入的神经信号电极,研究了神经信号的放大。为了使植入电极测得的神经信号能无线地传至体外,作者借助E类功率放大器的输出功率受负载电阻影响的特点,通过时分复用技术实现了多路神经信号的经皮传输与识别。文中叙述的植入体内的放大电路、经皮发射电路均是通过体外E类功率放大器发射的射频磁场经感应线圈而获得工作电源。最后用本研究研制的电路模拟神经信号控制多自由度假肢,验证了神经信号的放大、经皮传输、识别控制的过程。     

神经束内微电极提取大鼠坐骨神经信号的实验研究

基于已设计完成的植入式筛型微电极和神经信号调理电路,组成一个完整的系统,用于提取大鼠坐骨神经信号,以探索获取周围神经信息的方法.用显微外科技术将微电极植入于大鼠坐骨神经束中,通过微电极传导出神经束电信号,经信号调理电路处理后记录.已成功稳定导出的电信号波形经分析具有神经动作电位特征,验证了神经束内微电极可以获取大鼠坐骨神经信号.     

基于小波分析与神经网络相结合的表面肌电信号识别的研究

表面肌电信号是从人体骨骼肌表面通过电极记录下来的神经肌肉活动发放的生物电信号,具有非平稳性和复杂性的特点。本研究通过使用小波分析与神经网络相结合的方法,识别正常肌电信号与疲劳肌电信号。实验表明,将小波分解后的肌电信号代替原始肌电信号,能明显提高神经网络对肌电信号的识别准确率。     

人发角蛋白植入对大鼠脊髓损伤功能与形态的影响

目的：研究脊髓损伤后植入人发角蛋白（human hair keratin，HHK）对动物行为学影响及其对损伤脊髓的形态学影响与HHK本身的形态学变化。方法：采用重物下落撞击法制备大鼠脊髓损伤模型，在损伤处移植入HHK，分别于植入后5、10、15、20、25、30d进行行为学检查，于20d与30d脊髓进行形态学观察。结果：HHK植入后在30d内对大鼠的行为学影响与模型对照组没有统计学意义，但HHK可降解吸收融入损伤的脊髓组织，而受损伤的脊髓组织中可见大量胶质细胞、成纤维细胞与巨噬细胞浸润、神经纤维与髓鞘朗革非氏细胞。结论：HHK可能在脊髓损伤后的修复与重建中起作用。     

长期植入铂电极:对电极材料与神经组织的影响

神经的电子模拟已成为治疗中枢或周围神经系统紊乱病人的一种既定方法。这种治疗形式引起了有关组织与电极之间的相互作用而产生的长期植入的影响等问题。目前的研究目的是为了找到周围组织神经结构是否     

Selective recording of electroneurograms from the sciatic nerve of a dog with multi-electrode spiral cuffs

Electroneurograms (ENGs) from superficial regions of the sciatic nerve of a Beagle dog were recorded selectively with a chronically implanted 33-electrode spiral cuff (cuff). By delivering stimulating pulses to groups of three electrodes (GTEs) within the cuff we could define the relative positions of the particular superficial regions that selectively innervated the tibialis anterior (TA) and gastrocnemius muscles (GM). GTEs with and without contractions of the TA and GM muscles were selected and connected to a 4-channel ENG system designed to amplify ENGs by 100,000 times and to pass frequencies between 500 Hz and 10 kHz. In our study, 12 experiments were conducted on three Beagle dogs with a cuff implanted for up to 2 years. We present the results obtained in four experiments conducted on one animal. With the implanted leg mounted in a special electronic brace we applied extending forces to the ankle, rotating it by up to 37 degrees according to the neutral position, eliciting torque to stretch the TA muscle. Only the ENG from a GTE eliciting maximum contraction of the TA muscle showed activities corresponding to the trajectory of the mechanical load of the muscle. Next, we dissected the calcanean tendon (CT) of the implanted leg and applied repetitive pull forces to the CT. Only the ENG from the GTE eliciting maximum contraction of the GM muscle was activated in correspondence to the trajectory of the mechanical load applied on the CT. The results suggest that the cuff, implanted chronically on the sciatic nerve, is useful to record ENGs of the afferent fibers from TA and GM muscles selectively and that the technique could be extended for human use in the field of rehabilitation for paralysis.     

Simulation of intra-orbital optic nerve electrical stimulation

In blind subjects who still have functional retinal ganglion cells, electrical stimuli applied to the optic nerve can produce localised visual sensations. This has been demonstrated with an intracranially implanted self-sizing spiral cuff electrode, but, to avoid skull opening, intra-orbital cuff implantation is now considered. In its orbital segment, the optic nerve is surrounded by subarachnoidal cerebrospinal fluid (CSF) and dura mater. Dura mater is a tough fibrous tissue that can impede electrical stimulation. In the study, the issue of whether or not to remove the dura mater at the implantation site was addressed using simulation on numerical models. Several volume conductor models were built representing, respectively: the cuff implanted directly around the nerve; the cuff over the nerve after connective tissue encapsulated the implant; and the cuff electrode placed around the dura mater. Stimulation-induced electric potential fields were computed for these configurations using a full 3D finite elements software. Responses of fibres within the nerve were computed. A large range of dural conductivities and several CSF thicknesses were considered. In all simulated conditions, the presence of dura mater around a layer of CSF increased excitation thresholds. Selectivity performance also decreased, but was found to be independent of the CSF thickness. However, simulations showed that, if the diameter of the cuff electrode is adapted to the target nerve, the injected charge associated with activation is limited within a reasonable range. Electrical stimulation of the optic nerve with a cuff electrode implanted around the dura mater should therefore be feasible.     

Long-term recording from the chorda tympani nerve in rats

Cuff electrodes with headcap connectors were implanted around the rat chorda tympani nerve. Whole nerve recordings under anesthesia were made from these nerves every week to chemical, thermal and tactile stimuli applied to the anterior tongue. The signal/noise ratio of these recordings was similar to acute recordings from the chorda tympani nerve, and the nerves were spontaneously active. Responses to chemical as well as thermal and mechanical stimulation of the tongue were recorded as early as 2 and 3 weeks after implantation and recordings from the same nerve were made for more than 3 months. These results have demonstrated the feasibility of making long-term chronic recordings of chemosensory activity in the chorda tympani nerve. The cuff electrode has great potential to provide correlative information between neurophysiological and behavioral data.     

Wavelet based analysis and characterization of the ECG signal

We present details of the modelling, design, and experimental testing of an implantable system with a monopolar half-cuff electrode for selective stimulation of fibres within certain superficial regions of the human common peroneal nerve which is capable of making a selective activation of muscles, thus contributing to strong dorsal flexion and moderate eversion of the hemiplegic foot. The development of the cuff electrode was based partly on data obtained from histological examination of human common peroneal nerves, and from previously described models of excitation of myelinated nerve fibres. The modelling objectives were to determine the electric field that would be generated within the deep peroneal branch of the nerve by a monopolar half-cuff electrode installed on the nerve behind the lateral head of the fibula. The extent of initial excitation of the nerve fibres within the superficial region of the deep peroneal branch elicited by a monopolar half-cuff electrode was predicted. In the past 6 months two systems were implanted. In both patients significant improvements of gait dynamics were observed.     

Implantation of a newly developed direct optic nerve electrode device for artificial vision in rabbits

The purpose of this study was to investigate the surgical procedures involved in the implantation of a newly developed direct optic nerve electrode device for inducing artificial vision. The electrode device comprised seven wire stimulation electrodes and a return electrode (diameter 50?μm), one manipulation rod (diameter 100?μm), and a cylindrical silicone board (diameter 2.0?mm). The stimulation electrodes and the manipulation rod protruded through the board to allow implantation of the electrode tips into the optic disc of the rabbit eye. The surgical procedures required to insert the device into the vitreous cavity and implant the device into the optic disc were evaluated. When the electrodes were stimulated, electrically evoked potentials (EEPs) were recorded at the visual cortex. The electrode device was inserted into the vitreous cavity with no damage using a trocar through a scleral incision. The device was easily manipulated using vitreoretinal forceps in the vitreous cavity, and the electrode tips were implanted into the optic disc in a single insertion after vitrectomy. When electrical stimulation was applied, EEPs were recorded from all electrode pairs. The newly developed electrode device was inserted into the eye and implanted into the optic nerve disc smoothly and safely, suggesting that these surgical procedures are useful for our artificial vision system.     

长期置入骶神经根刺激电极的兔组织学变化及其安全性

背景：有研究表明基于阳极阻滞技术的骶神经根刺激器能有效重建脊髓损伤兔的膀胱排尿功能,但符合此技术的刺激电极至今未见报道。 目的：设计并研制既与兔骶神经根匹配又符合阳极阻滞技术的刺激电极,观察长期植入刺激电极的兔骶神经根超微结构及病理形态学变化,评估刺激电极安全性。 方法：纳入新西兰兔30只,随机抽取10只兔切取双侧S2及S3神经前根,光镜下测量其直径后,制成与其直径相匹配的套筒型刺激电极。将剩余20只兔随机分为对照组及植入组,每组10只。植入组麻醉后将刺激电极植入S2及S3神经根前处,饲养半年后处死取材,观察植入处骶神经根超微结构变化。 结果与结论：长期植入该刺激电极后,光学显微镜下见植入组植入处骶神经根神经细胞结构保存良好,轴突无明显变性,无炎症细胞浸润及胶质瘢痕形成;透射电镜下观察,植入组髓鞘排列紧密,无脱髓鞘现象,神经元无核萎缩、核凹陷和异染色质增多等现象。免疫组织化学染色显示,与对照组相比,植入组植入处神经根中胶质纤维酸性蛋白、Bax,Bcl-2和Caspase-3蛋白表达差异无显著性意义。结果说明实验成功研制了兔骶神经根刺激电极,长期植入骶神经根未出现组织病理学改变及无细胞凋亡现象,安全性好。     

An intrafascicular electrode for recording of action potentials in peripheral nerves

We are developing a new type of bipolar recording electrode intended for implantation within individual fascicles of mammalian peripheral nerves. In the experiments reported here we used electrodes fabricated from 25 μm diameter Pt wire, 50 μm 90% Pt-10% Ir wire and 7 μm carbon fibers. The electrodes were implanted in the sciatic nerves of rats and in the ulnar nerves of cats. The signal-to-noise ratio of recorded activity induced by nonnoxious mechanical stimulation of the skin and joints was studied as a function of the type of electrode material used, the amount of insulation removed from the recording zone, and the longitudinal separation of the recording zones of bipolar electrode pairs. Both acute and short term (two day) chronic experiments were performed. The results indicate that a bipolar electrode made from Teflon^™-insulated, 25 μm diameter, 90% Pt-10% Ir wire, having a 1–2 mm long recording zone, can be used for recording of peripheral nerve activity when implanted with one wire inside the fascicle and the other lead level with the first lead, but outside the fascicle. No insulating cuff needs to be placed around the nerve trunk.     

Long-term biocompatibility of implanted polymer-based intrafascicular electrodes

Polymer-based longitudinal intrafascicular electrodes (polyLIFEs) were chronically implanted into the sciatic nerve of white New Zealand rabbits (n=8) for a period of 6 months (hereafter referred to as the long-term group). The impact of the implantation procedure, as observed 6 months post surgery, was evaluated in a sham-treated control group (n=9). The contralateral sciatic nerve served as the control for each animal. Nerve-fiber counts, fiber diameters, and myelin thickness were estimated at the level of the implant site, 1.5 cm proximally, and 1.5 cm distally for both nerves in sham-treated and long-term groups. Implantation of polyLIFEs had no significant effect on fiber counts, nerve-fiber diameter, or myelin thickness. A slight increase in connective tissue in the vicinity of the implant site was evident in the long-term group, including a thin but dense capsule immediately surrounding the implanted electrode.     

Electric field aspects in hypoglossal nerve stimulation for obstructive sleep apnea: A bilateral electrophysiological evaluation of unilateral electrode configuration changes

Hypoglossal nerve stimulation is an established treatment option for obstructive sleep apnea in selected patients. A unilateral hypoglossal nerve stimulation system was approved a decade ago, yet the physiological effect of unilateral hypoglossal stimulation on bilateral tongue motion remains unclear. This study examined how electrode configuration, stimulation cuff position, or body mass index influenced the contralateral genioglossus electromyography (EMG) signal. Twenty-nine patients underwent three EMG recordings in a polysomnographic setting after being implanted with a unilateral hypoglossal nerve stimulator for at least 6 months. The ratio of EMG signals between the ipsi- and contralateral sides was evaluated. No difference in EMG signals was demonstrated based on electrode configurations, stimulation-cuff position, body-mass-index, or sleep apnea severity, even in patients with right tongue protrusion only. Our findings may be explained by a significant level of cross-innervation and by a smaller and less variable circumferential electric field than expected based on prior biophysical models. A patient's individual anatomy needs to be considered during therapy titration in order to achieve an optimal response.     

Evaluation of peripheral nerve regeneration across an 80-mm gap using a polyglycolic acid (PGA)--collagen nerve conduit filled with laminin-soaked collagen sponge in dogs

We evaluated peripheral nerve regeneration using a novel artificial nerve conduit. The conduit was made of a polyglycolic acid(PGA) - collagen tube filled with laminin- soaked collagen sponge. We implanted this nerve conduit across an 80mm gap in the peroneal nerve of dogs. Histological observation 12 months after implantation showed numerous unmyelinated and myelinated nerve fibershad regenerated beyond the gap. Neurofilaments were widely observed immunohistochemically in the regenerated nerve segments. These findings indicated that newly regenerated axons had extended across the gap and connected into the distal nerve segments. Compound muscle action potentials(CMAPs) and somatosensory evoked potentials (SEPs) were recorded in all dogs. At 12 months, the CMAPs indicated complete recovery, while the SEPs showed incomplete but substantial recovery. Walking patterns had returned to near-normal 12 months after implantation. Use of this nerve conduit can lead to peripheral nerve elongation and favorable functional recovery across a wider nerve gap.