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1.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 35(6): 860-863, 2018 12 25.
Artigo em Chinês | MEDLINE | ID: mdl-30583309

RESUMO

Functional electronic stimulation (FES) may provide a means to restore motor function in patients with spinal cord injuries. The goal of this study is to determine the regions in the spinal cord controlling different hindlimb movements in the rats. Normalization was used for the regions dominating the corresponding movements. It has been verified that FES can be used in motor function recovery of the hindlimb. The spinal cord was stimulated by FES with a three-dimensional scan mode in experiments. The results show that stimulation through the electrodes implanted in the ventral locations of the lumbosacral enlargement can produce coordinated single- and multi-joint hindlimb movements. A variety of different hindlimb movements can be induced with the appropriate stimulation sites, and movement vectors of the hindlimb cover the full range of movement directions in the sagittal plane of the hindlimb. This article drew a map about spinal cord motor function of the rat. The regions in the spinal cord which control corresponding movements are normalized. The data in the study provide guidance about the location of electrode tips in the follow-up experiments.

2.
Sensors (Basel) ; 16(4)2016 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-27058539

RESUMO

In recent years, there has emerged applications of vehicular ad hoc networks (VANETs) towards security, safety, rescue, exploration, military and communication redundancy systems in non-populated areas, besides its ordinary use in urban environments as an essential part of intelligent transportation systems (ITS). This paper proposes a novel algorithm for the process of organizing a cluster structure and cluster head election (CHE) suitable for VANETs. Moreover, it presents a robust clustering-based routing protocol, which is appropriate for deserts and can achieve high communication efficiency, ensuring reliable information delivery and optimal exploitation of the equipment on each vehicle. A comprehensive simulation is conducted to evaluate the performance of the proposed CHE and routing algorithms.

3.
IEEE Trans Biomed Circuits Syst ; 18(1): 100-110, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37665710

RESUMO

This article introduces a Combined .symmetrical and complementary Input Pairs (CIP) of a Differential Difference Amplifier (DDA), to boost the total Common-Mode Rejection Ratio (CMRR) for multi-channel neural signal recording. The proposed CIP-DDA employs three input pairs (transconductors). The dc-coupled input neural signal connection, via the gate terminal of the first transconductor, yields a high input impedance. The high-pass corner frequency and dc quiescent operation point are stabilized by the second transconductor. The calibration path of differential-mode gain and Common-Mode Feedback (CMFB) is provided by the proposed third transconductor. The parallel connection has no need for extra voltage headroom of input and output. The proposed CIP-DDA is targeted at integrated circuit realization and designed in a 0.18-µm CMOS technology. The proposed CIP-DDAs with system CMFB achieve an average CMRR of 103 dB, and each channel consumes circa 3.6 µW power consumption.


Assuntos
Ácido Aminossalicílico , Amplificadores Eletrônicos , Desenho de Equipamento , Retroalimentação , Tecnologia
4.
Artigo em Inglês | MEDLINE | ID: mdl-37018337

RESUMO

Epidural spinal cord stimulation (ESCS) is a potential treatment for the recovery of the motor function in spinal cord injury (SCI) patients. Since the mechanism of ESCS remains unclear, it is necessary to study the neurophysiological principles in animal experiments and standardize the clinical treatment. In this paper, an ESCS system is proposed for animal experimental study. The proposed system provides a fully implantable and programmable stimulating system for complete SCI rat model, along with a wireless charging power solution. The system is composed of an implantable pulse generator (IPG), a stimulating electrode, an external charging module and an Android application (APP) via a smartphone. The IPG has an area of 25×25 mm2 and can output 8 channels of stimulating currents. Stimulating parameters, including amplitude, frequency, pulse width and sequence, can be programmed through the APP. The IPG was encapsulated with a zirconia ceramic shell and two-month implantable experiments were carried out in 5 rats with SCI. The main focus of the animal experiment was to show that the ESCS system could work stably in SCI rats. The IPG implanted in vivo can be charged through the external charging module in vitro without anesthetizing the rats. The stimulating electrode was implanted according to the distribution of ESCS motor function regions of rats and fixed on the vertebrae. The lower limb muscles of SCI rats can be activated effectively. The two-month SCI rats needed greater stimulating current intensity than the one-month SCI rats The results indicated that the stimulating system provides an effective and simplified tool for studying the ESCS application in motor function recovery for untethered animals.

5.
PLoS One ; 17(3): e0265078, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35263381

RESUMO

The aim of this paper was to investigate the influence of four different external factors (acetylcholine, ethanol, temperature and lidocaine hydrochloride) on PC12 quasi-neuronal networks by multielectrode-array-based Voltage Threshold Measurement Method (VTMM). At first, VTMM was employed to measure the lowest amplitude of the voltage stimulating pulses that could just trigger the action potential from PC12 quasi-neuronal networks under normal conditions, and the amplitude was defined as the normal voltage threshold (VTh). Then the changes of the VTh of PC12 quasi-neuronal networks treated by the four external factors were tested respectively. The results showed the normal VTh of PC12 quasi-neuronal networks was 36 mV. The VTh has negative correlation with the concentration of acetylcholine and has positive correlation with the concentration of ethanol. The curves of the correlation of the VTh with temperature and the concentration of lidocaine hydrochloride were U-shaped and Λ-shaped respectively. Comparing with our earlier studies on hippocampal neuronal networks and hippocampal slices, PC12 quasi-neuronal networks not only had the same typical voltage threshold characteristic, but also had similar changes on electrical excitability when treated by the four external factors mentioned above. Therefore, the rapid-formed PC12 quasi-neuronal networks could replace neuronal networks in proper conditions, and VTMM could be used to analyze the influence of external factors on the electrical excitability of PC12 quasi-neuronal networks.


Assuntos
Acetilcolina , Neurônios , Potenciais de Ação/fisiologia , Etanol/farmacologia , Lidocaína/farmacologia , Neurônios/fisiologia
6.
PLoS One ; 17(12): e0277942, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36512588

RESUMO

The aim of this study was to investigate the toxic effects and mechanism of silver nanoparticles (SNPs) on the cytological and electrophysiological properties of rat adrenal pheochromocytoma (PC12) cells. Different concentrations of SNPs (20 nm) were prepared, and the effects of different application durations on the cell viability and electrical excitability of PC12 quasi-neuronal networks were investigated. The effects of 200 µM SNPs on the neurite length, cell membrane potential (CMP) difference, intracellular Ca2+ content, mitochondrial membrane potential (MMP) difference, adenosine triphosphate (ATP) content, and reactive oxygen species (ROS) content of networks were then investigated. The results showed that 200 µM SNPs produced grade 1 cytotoxicity at 48 h of interaction, and the other concentrations of SNPs were noncytotoxic. Noncytotoxic 5 µM SNPs significantly increased electrical excitability, and noncytotoxic 100 µM SNPs led to an initial increase followed by a significant decrease in electrical excitability. Cytotoxic SNPs (200 µM) significantly decreased electrical excitability. SNPs (200 µM) led to decreases in neurite length, MMP difference and ATP content and increases in CMP difference and intracellular Ca2+ and ROS levels. The results revealed that not only cell viability but also electrophysiological properties should be considered when evaluating nanoparticle-induced neurotoxicity. The SNP-induced cytotoxicity mainly originated from its effects on ATP content, cytoskeletal structure and ROS content. The decrease in electrical excitability was mainly due to the decrease in ATP content. ATP content may thus be an important indicator of both cell viability and electrical excitability in PC12 quasi-neuronal networks.


Assuntos
Nanopartículas Metálicas , Prata , Animais , Ratos , Trifosfato de Adenosina/metabolismo , Apoptose , Cálcio/metabolismo , Sobrevivência Celular , Nanopartículas Metálicas/toxicidade , Neurônios/metabolismo , Células PC12 , Espécies Reativas de Oxigênio/metabolismo , Prata/farmacologia
7.
Neural Regen Res ; 17(3): 601-607, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34380900

RESUMO

Epidural stimulation of the spinal cord is a promising technique for the recovery of motor function after spinal cord injury. The key challenges within the reconstruction of motor function for paralyzed limbs are the precise control of sites and parameters of stimulation. To activate lower-limb muscles precisely by epidural spinal cord stimulation, we proposed a high-density, flexible electrode array. We determined the regions of motor function that were activated upon epidural stimulation of the spinal cord in a rat model with complete spinal cord, which was established by a transection method. For evaluating the effect of stimulation, the evoked potentials were recorded from bilateral lower-limb muscles, including the vastus lateralis, semitendinosus, tibialis anterior, and medial gastrocnemius. To determine the appropriate stimulation sites and parameters of the lower muscles, the stimulation characteristics were studied within the regions in which motor function was activated upon spinal cord stimulation. In the vastus lateralis and medial gastrocnemius, these regions were symmetrically located at the lateral site of L1 and the medial site of L2 vertebrae segment, respectively. The tibialis anterior and semitendinosus only responded to stimulation simultaneously with other muscles. The minimum and maximum stimulation threshold currents of the vastus lateralis were higher than those of the medial gastrocnemius. Our results demonstrate the ability to identify specific stimulation sites of lower muscles using a high-density and flexible array. They also provide a reference for selecting the appropriate conditions for implantable stimulation for animal models of spinal cord injury. This study was approved by the Animal Research Committee of Southeast University, China (approval No. 20190720001) on July 20, 2019.

8.
Artigo em Inglês | MEDLINE | ID: mdl-34723805

RESUMO

Spasticity is a common motor disorder following a variety of upper motor neuron lesions that seriously affects the quality of patient's life. We aimed to evaluate whether muscle spasms can be suppressed by blocking nerve signal conduction. A rat model of lower limb spasm was prepared and the conduction of pathological nerve signals were blocked to study the inhibitory effect of nerve signal block on muscle spasm. The experimental results showed that 4 weeks after the 9th segment of the rat's thoracic spinal cord was completely transacted, the H/M -ratio of the lower limbs increased, and rate-dependent depression was weakened. When the rat model was stimulated by external forces, the electromyography (EMG) signals of the spastic gastrocnemius muscles continued to erupt. After blocking the conduction of nerve signals in the rat sciatic nerve, the spastic EMG signal of the gastrocnemius muscle disappeared. The effective blocking time and blocking efficiency increased with increasing blocking signal amplitude, and the maximum blocking efficiency reached 73%. The experimental results of this study proved the feasibility of inhibiting lower limb spasticity by blocking nerve signal conduction.


Assuntos
Bloqueio Nervoso , Traumatismos da Medula Espinal , Animais , Eletromiografia , Espasticidade Muscular , Músculo Esquelético , Condução Nervosa , Ratos , Medula Espinal
9.
Neurosci Lett ; 751: 135801, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33705932

RESUMO

Lidocaine hydrochloride (LC-HCl) and morphine hydrochloride (Mor-HCl) are two kinds of most prevalently used anesthetics. However, their influences on electrical excitability of hippocampal neuronal networks and hippocampal brain slices were rarely studied. Previously, our group have assessed the influence of acetylcholine, alcohol and temperature change on the excitability of neural networks with the so-called Voltage Threshold Measurement Method (VTMM) based on microelectrode array (MEA). In this paper, we will study the influence of LC-HCl and Mor-HCl on the electrical excitability of neural networks and the morphological features of neurons, and discuss the relations between the changes of electrical excitability of neural networks and the morphological changes of neurons. The results of VTMM showed: The voltage threshold (VTh) of hippocampal neuronal networks and hippocampal brain slices first increased and then decreased as the LC-HCl concentration increased. The VTh of hippocampal neuronal networks and hippocampal brain slices increased as the Mor-HCl concentration increased. The results of HCS experiments showed: The neurite length change of cultured hippocampal neuronal networks increased first and then decreased with increased LC-HCl concentration, but decreased as the Mor-HCl concentration increased. The combined analysis of VTMM and HCS experiments showed that under effects of the two drugs, the VTh and the hippocampal neurite length were strongly negatively correlated.


Assuntos
Hipocampo/efeitos dos fármacos , Lidocaína/farmacologia , Morfina/farmacologia , Crescimento Neuronal/efeitos dos fármacos , Analgésicos Opioides/farmacologia , Anestésicos Locais/farmacologia , Animais , Células Cultivadas , Interações Medicamentosas , Hipocampo/citologia , Hipocampo/fisiologia , Potenciais da Membrana , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Ratos , Ratos Sprague-Dawley
10.
Neural Regen Res ; 16(3): 567-572, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32985489

RESUMO

Functional electrical stimulation is an effective way to rebuild hindlimb motor function after spinal cord injury. However, no site map exists to serve as a reference for implanting stimulator electrodes. In this study, rat models of thoracic spinal nerve 9 contusion were established by a heavy-impact method and rat models of T6/8/9 spinal cord injury were established by a transection method. Intraspinal microstimulation was performed to record motion types, site coordinates, and threshold currents induced by stimulation. After transection (complete injury), the core region of hip flexion migrated from the T13 to T12 vertebral segment, and the core region of hip extension migrated from the L1 to T13 vertebral segment. Migration was affected by post-transection time, but not transection segment. Moreover, the longer the post-transection time, the longer the distance of migration. This study provides a reference for spinal electrode implantation after spinal cord injury. This study was approved by the Institutional Animal Care and Use Committee of Nantong University, China (approval No. 20190225-008) on February 26, 2019.

11.
J Neural Eng ; 18(4)2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33836509

RESUMO

Objective. In this study, a hybrid method combining hardware and software architecture is proposed to remove stimulation artefacts (SAs) and extract the volitional surface electromyography (sEMG) in real time during functional electrical stimulations (FES) with time-variant parameters.Approach. First, an sEMG detection front-end (DFE) combining fast recovery, detector and stimulator isolation and blanking is developed and is capable of preventing DFE saturation with a blanking time of 7.6 ms. The fragment between the present stimulus and previous stimulus is set as an SA fragment. Second, an SA database is established to provide six high-similarity templates with the current SA fragment. The SA fragment will be de-artefacted by a 6th-order Gram-Schmidt (GS) algorithm, a template-subtracting method, using the provided templates, and this database-based GS algorithm is called DBGS. The provided templates are previously collected SA fragments with the same or a similar evoking FES intensity to that of the current SA fragment, and the lengths of the templates are longer than that of the current SA fragment. After denoising, the sEMG will be extracted, and the current SA fragment will be added to the SA database. The prototype system based on DBGS was tested on eight able-bodied volunteers and three individuals with stroke to verify its capacity for stimulation removal and sEMG extraction.Results.The average stimulus artefact attenuation factor, SA index and correlation coefficient between clean sEMG and extracted sEMG for 6th-order DBGS were 12.77 ± 0.85 dB, 1.82 ± 0.37 dB and 0.84 ± 0.33 dB, respectively, which were significantly higher than those for empirical mode decomposition combined with notch filters, pulse-triggered GS algorithm, 1st-order and 3rd-order DBGS. The sEMG-torque correlation coefficients were 0.78 ± 0.05 and 0.48 ± 0.11 for able-bodied volunteers and individuals with stroke, respectively.Significance.The proposed hybrid method can extract sEMG during dynamic FES in real time.


Assuntos
Algoritmos , Artefatos , Estimulação Elétrica , Eletromiografia , Humanos , Volição
12.
IEEE Trans Neural Syst Rehabil Eng ; 28(5): 1069-1080, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32167902

RESUMO

OBJECTIVES: The goal of this study is to design a novel approach for extracting volitional electromyography (vEMG) contaminated by functional electrical stimulation (FES) with time variant amplitudes and frequencies. METHODS: A selective interpolation (SI) is adopted to eliminate the initial spike. Then the interpolated signal is decomposed into intrinsic mode functions by using complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). Each IMF is window-filtered based on a logistic regression (LR) classifier to identify the IMFs contaminated by FES. Semi-simulated signals were generated using EMG and stimulation response and three metrics were adopted to validate the performance of the proposed algorithm, including the a) signal-to-noise ratio (SNR), b) normalized root mean squared error (NRMSE) and c) cross-correlation coefficient between the clean EMG and the extracted EMG. Real FES-contaminated EMG was collected from six able bodied volunteers and one stroke patient. The correlation coefficients between the extracted EMG and the wrist torque were analyzed. RESULTS: The simulation results showed a higher SNR (2.12 to -2.13dB), higher correlation (0.88± 0.08) and lower NRMSE (0.78 to 1.29) than those of the comb filter and EMD-Notch algorithm. The EMG-Torque correlation coefficients were 0.75± 0.07 for monopolar pulses and 0.77± 0.12 for bipolar pulses. For the stroke patient, the algorithm also successfully extracted underlying vEMG from time variant FES noises. CONCLUSIONS: All results showed that SICEEMDAN-LR is capable of extracting EMG during FES with time-variant parameters.


Assuntos
Algoritmos , Articulação do Punho , Estimulação Elétrica , Eletromiografia , Humanos , Razão Sinal-Ruído
13.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3819-3822, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018833

RESUMO

Different neural signal blocking technologies provide potential therapy for various diseases caused by pathological or involuntary neural activities. In this paper, a novel neural signal blocking concept based on spike-trapping principle is introduced. The blocking system was designed and implemented. In the system, a compound action potential was induced by a proximal stimulus, and a blocking signal was generated after a neural signal was detected, which was applied to the distal end of the nerve to block the nerve conduction. The reliability of the system was verified on bullfrog sciatic nerve gastrocnemius muscle specimens. The optimal blocking signal parameters, the relationship between nerve diameter and blocking threshold voltage, and the nerve safety of blocking signals were explored. The experimental results show that the system is possible to block a pathological or involuntary neural signal automatically. The average voltage of block threshold and the minimum pulse width are -1.66 V and 120 ms, respectively. The blocking threshold decreases as the diameter of the nerve increases. The blocking signals at the threshold level are safe for the stimulated nerve.


Assuntos
Bloqueio Nervoso , Nervo Isquiático , Potenciais de Ação , Animais , Condução Nervosa , Reprodutibilidade dos Testes
14.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4126-4129, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018906

RESUMO

A surface electromyography (sEMG) detector, that not only removes stimulation artifacts entirely but also increases the recording time, has been developed in this paper. The sEMG detector consists of an sEMG detection circuit and a stimulation isolator. The sEMG detection circuit employs a stimulus isolate switch (SIS), a blanking (BLK) and non-linear feed-back (NFB) circuit to remove the artifacts and to increase the recording time. In the SIS, the connection between stimulator and stimulation electrodes, along with the stimulation electrodes and the ground are controlled by an opto-isolator, and the connection of instrument amplifier and the recording electrodes are controlled by CMOS-based switches. The mode switches of the BLK and the NFB circuit also employs CMOS-based switches. By an accurate timing adjustment, the voluntary EMG can be recorded during electrical stimulation. Two 6 able-bodied experiments have been performed to test the three anti-artifact sEMG detector: BLK, BLK&SIS, BLK&SIS&NFB. The results indicate that the BLK&SIS&NFB proposed in this work effectively removes stimulus artifacts and M-waves, and has a longer recording time compared with BLK and BLK&SIS circuits.


Assuntos
Amplificadores Eletrônicos , Artefatos , Estimulação Elétrica , Eletrodos , Eletromiografia
15.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 5220-5223, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019161

RESUMO

The aim of this study is to design an implantable Lower Esophageal Sphincter (LES) stimulator connected and controlled by an Android Bluetooth for the treatment of the gastroesophageal reflux disease (GERD). Then the animal experiments are carried out to evaluate the function of the system. The LES stimulator is composed of an external controller, an Android application (APP) via a smart phone and an implantable electronic device (IED). The external controller is designed to receive the settings parameters information sent by the Android APP via a Bluetooth module, and then is programmed to generate specific electrical stimulation pulses to the LES. The Android APP controls the start and stop of stimulation and the settings of stimulation parameters. The in vivo IED consists of a bipolar stimulating lead, a bipolar head connector and a receiving module. The bipolar stimulating lead is constructed of biocompatible materials: platinum-iridium electrodes which are coated with parylene and an outer silicone rubber sheathing. The size of the receiving module has been significantly decreased to 20×20×2 mm3, which is packaged by polydimethylsiloxane (PDMS) and proposed to deliver stimulation pulses from the external controller to the implantable lead. The one-month implantation experiment on rabbits has been performed to evaluate the LES stimulator. The results indicate that the proposed LES stimulator meets the requirements of the functions, effectiveness and safety.


Assuntos
Terapia por Estimulação Elétrica , Refluxo Gastroesofágico , Animais , Estimulação Elétrica , Esfíncter Esofágico Inferior , Refluxo Gastroesofágico/terapia , Próteses e Implantes , Coelhos
16.
Annu Int Conf IEEE Eng Med Biol Soc ; 2019: 3795-3798, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31946700

RESUMO

Intraspinal microstimulation and epidural spinal cord stimulation can be considered as the technique to restore function following spinal cord injury through further research. In this paper, the automatic brain stereotaxic instrument was used to electrically stimulate the lumbosacral spinal cord (T12-L2 spinal segments) in rats. The motor function regions under intraspinal microstimulation and epidural spinal cord stimulation were measured. Threshold currents and coordinate sites of related motions were recorded. Comparative analysis revealed that the threshold current required for epidural stimulation to induce hindlimb motion was greater. Although the distribution of motor function regions measured by these two methods differed in the type of motion, the segment distribution of each motion were roughly the same. Therefore, if conditions permit, epidural stimulation can be used instead of intraspinal microstimulation to reduce secondary damage to the spinal cord. This provides a reference for locating stimulation sites for epidural spinal cord stimulation.


Assuntos
Traumatismos da Medula Espinal , Estimulação da Medula Espinal , Animais , Estimulação Elétrica , Espaço Epidural , Membro Posterior , Humanos , Ratos , Medula Espinal , Traumatismos da Medula Espinal/terapia
17.
Neural Regen Res ; 13(6): 1026-1035, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29926830

RESUMO

The electrical excitability of neural networks is influenced by different environmental factors. Effective and simple methods are required to objectively and quantitatively evaluate the influence of such factors, including variations in temperature and pharmaceutical dosage. The aim of this paper was to introduce 'the voltage threshold measurement method', which is a new method using microelectrode arrays that can quantitatively evaluate the influence of different factors on the electrical excitability of neural networks. We sought to verify the feasibility and efficacy of the method by studying the effects of acetylcholine, ethanol, and temperature on hippocampal neuronal networks and hippocampal brain slices. First, we determined the voltage of the stimulation pulse signal that elicited action potentials in the two types of neural networks under normal conditions. Second, we obtained the voltage thresholds for the two types of neural networks under different concentrations of acetylcholine, ethanol, and different temperatures. Finally, we obtained the relationship between voltage threshold and the three influential factors. Our results indicated that the normal voltage thresholds of the hippocampal neuronal network and hippocampal slice preparation were 56 and 31 mV, respectively. The voltage thresholds of the two types of neural networks were inversely proportional to acetylcholine concentration, and had an exponential dependency on ethanol concentration. The curves of the voltage threshold and the temperature of the medium for the two types of neural networks were U-shaped. The hippocampal neuronal network and hippocampal slice preparations lost their excitability when the temperature of the medium decreased below 34 and 33°C or increased above 42 and 43°C, respectively. These results demonstrate that the voltage threshold measurement method is effective and simple for examining the performance/excitability of neuronal networks.

18.
PLoS One ; 13(1): e0190936, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29324829

RESUMO

It is still challenging to achieve a complex grasp or fine finger control by using surface functional electrical stimulation (FES), which usually requires a precise electrode configuration under laboratory or clinical settings. The goals of this study are as follows: 1) to study the possibility of selectively activating individual fingers; 2) to investigate whether the current activation threshold and selective range of individual fingers are affected by two factors: changes in the electrode position and forearm rotation (pronation, neutral and supination); and 3) to explore a theoretical model for guidance of the electrode placement used for selective activation of individual fingers. A coordinate system with more than 400 grid points was established over the forearm skin surface. A searching procedure was used to traverse all grid points to identify the stimulation points for finger extension/flexion by applying monophasic stimulation pulses. Some of the stimulation points for finger extension and flexion were selected and tested in their respective two different forearm postures according to the number and the type of the activated fingers and the strength of finger action response to the electrical stimulation at the stimulation point. The activation thresholds and current ranges of the selectively activated finger at each stimulation point were determined by visual analysis. The stimulation points were divided into three groups ("Low", "Medium" and "High") according to the thresholds of the 1st activated fingers. The angles produced by the selectively activated finger within selective current ranges were measured and analyzed. Selective stimulation of extension/flexion is possible for most fingers. Small changes in electrode position and forearm rotation have no significant effect on the threshold amplitude and the current range for the selective activation of most fingers (p > 0.05). The current range is the largest (more than 2 mA) for selective activation of the thumb, followed by those for the index, ring, middle and little fingers. The stimulation points in the "Low" group for all five fingers lead to noticeable finger angles at low current intensity, especially for the index, middle, and ring fingers. The slopes of the finger angle variation in the "Low" group for digits 2~4 are inversely proportional to the current intensity, whereas the slopes of the finger angle variation in other groups and in all groups for the thumb and little finger are proportional to the current intensity. It is possible to selectively activate the extension/flexion of most fingers by stimulating the forearm muscles. The physiological characteristics of each finger should be considered when placing the negative electrode for selective stimulation of individual fingers. The electrode placement used for the selective activation of individual fingers should not be confined to the location with the lowest activation threshold.


Assuntos
Estimulação Elétrica/métodos , Eletrodos , Dedos/fisiologia , Antebraço/fisiologia , Movimento/fisiologia , Contração Muscular/fisiologia , Adulto , Análise de Variância , Fenômenos Biomecânicos , Estimulação Elétrica/instrumentação , Feminino , Antebraço/anatomia & histologia , Humanos , Masculino , Músculo Esquelético/fisiologia , Tamanho do Órgão , Adulto Jovem
19.
Annu Int Conf IEEE Eng Med Biol Soc ; 2018: 2260-2263, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30440856

RESUMO

A method of blocking neural signal for spasticity which is based on the antimissile strategy was proposed. When the pathological nerve action potential signal is detected at the proximal end of the nerve, such a potential signal that is opposite to the signal of the primary neural activity is applied at the distal end of the nerve at a proper delay so as to block the pathological nerve signal. Preliminary tests were performed on toad sciatic nerve-gastrocnemius specimens. Firstly, the effect of the distance between blocking electrodes on the blocking pulse voltage threshold was studied based on the electrical tension induced by the nerve signal on the controlled muscle. Then, the effective parameters of the blocking waveform were studied. Finally, the delay range of the blocking pulse compared to the pathogen action potential was studied. The results showed that in the sciatic nerve-gastrocnemius specimens, the most effective distance between the blocking electrode pairs was 5 mm and the anodic block required an inverted triangle waveform. The voltage threshold of an effective anodic blocking pulse was 1 V and the minimum pulse width was 90 ms. Under the condition of voltage threshold and minimum pulse width, the time shifting value of blocking pulse was greater than 1ms. It is concluded from the study that the spastic action potential caused by the disease can be effectively blocked, and limb muscle spasms can be eliminated under the action of appropriate electrode configuration and blocking signal waveforms.


Assuntos
Extremidades , Espasticidade Muscular , Bloqueio Nervoso , Potenciais de Ação , Estimulação Elétrica , Extremidades/fisiologia , Humanos , Espasticidade Muscular/prevenção & controle , Espasticidade Muscular/terapia , Nervo Isquiático
20.
Neural Regen Res ; 12(1): 133-142, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28250759

RESUMO

Voluntary participation of hemiplegic patients is crucial for functional electrical stimulation therapy. A wearable functional electrical stimulation system has been proposed for real-time volitional hand motor function control using the electromyography bridge method. Through a series of novel design concepts, including the integration of a detecting circuit and an analog-to-digital converter, a miniaturized functional electrical stimulation circuit technique, a low-power super-regeneration chip for wireless receiving, and two wearable armbands, a prototype system has been established with reduced size, power, and overall cost. Based on wrist joint torque reproduction and classification experiments performed on six healthy subjects, the optimized surface electromyography thresholds and trained logistic regression classifier parameters were statistically chosen to establish wrist and hand motion control with high accuracy. Test results showed that wrist flexion/extension, hand grasp, and finger extension could be reproduced with high accuracy and low latency. This system can build a bridge of information transmission between healthy limbs and paralyzed limbs, effectively improve voluntary participation of hemiplegic patients, and elevate efficiency of rehabilitation training.

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