BACKGROUND：Amyotrophic lateral sclerosis （ALS） is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Elect...BACKGROUND：Amyotrophic lateral sclerosis （ALS） is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Electrodiagnostic tests play a fundamental role in quantifying pathological changes in the motor unit pool.OBJECTIVE：We assessed distal-proximal Motor Unit （MU） loss and changes using the method of motor unit number estimation （MUNE）.DESIGN, TIME AND SETTING：A case-control study was performed at the Department of Neuroscience, Pisa University Medical School, Italy from December 1999 to November 2009. PARTICIPANTS：A total of 50 ALS patients were recruited, 30 males：mean age （59.6 ± 13.3） years; 20 females：mean age （63.9 ± 11.7） years; range （30-82） years; all patients had probable or definite ALS. Thirty healthy volunteers were recruited from department staffs, including 20 males and 10 females; mean age （57.7 ± 13.8） years served as controls.METHODS：MUNE was performed for both the biceps brachii and abductor digiti minimi muscles of the same side. The technique used relayed substantially on manual incremental stimulation of the motor nerve, known as the McComas technique （50 ms sweep duration, a gain of 2 mV/Div for M wave, 0.5 mV/Div for each step; filters 10-20 kHz）.MAIN OUTCOME MEASURES：MUNE results were measured.RESULTS：Functioning MU numbers, measured by MUNE, decreased in the biceps brachii and abductor digiti minimi muscles over the entire one-year follow-up period （one assessment every three months） compared with baseline determination, the rate of MU decrease was similar in both muscles, but steeper distally.CONCLUSION：MUNE is a feasible method for ALS patients both proximally and distally to track changes over time in muscle MUs during the disease＇s evolution.展开更多
The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when ...The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when the maximal level is achieved. The study included 110 participants. To assess the contractile characteristics of leg extensors, standardized equipment and standardized isometric test in sitting position with the angle of the knee joint of 125° were used. The participants were instructed to exert their maximal force as quickly as possible. Using descriptive statistics, cluster analysis and fitting the exponential model of the distribution of force of leg extensor motor units in the whole range of force generation is defined. The model has the following form： y = 0.2051e3.3855x, where y is the motor units force expressed in daN （decanewtons）, x is the time expressed in s （seconds）. It provides an understanding of the control of multivariate motor unit recruitment and distribution of their force during sports movements as well as training programming for the adoption of forms for conlrolling force distribution of motor units, the development of their maximum force and their involvement speed.展开更多
To examine the contralateral repeated bout effect(CL-RBE)on muscle damage markers and motor unit(MU)control strategies,seventeen healthy adults performed two bouts of 60 eccentric contractions with elbow flexor(EF gro...To examine the contralateral repeated bout effect(CL-RBE)on muscle damage markers and motor unit(MU)control strategies,seventeen healthy adults performed two bouts of 60 eccentric contractions with elbow flexor(EF group;n=9)or index finger abductor(IA group;n=8)muscles,separated by 1 week.All participants randomly performed eccentric exercise on either the right or left arm or hand muscles,and muscle damage markers and submaximal trapezoid contraction tests were conducted pre,post,1-and 2-day post eccentric protocol.One week after the first bout,the same exercise protocol and measurements were performed on the contralateral muscles.Surface electromyographic(EMG)signals were collected from biceps brachii(BB)or first dorsal interosseous(FDI)during maximal and submaximal tests.The linear regression analyses were used to examine MU recruitment threshold versus mean firing rate and recruitment threshold versus derecruitment threshold relationships.EMG amplitude from BB(bout 1 vs.bout 2=65.71%±22.92%vs.43.05%±18.97%,p=0.015,d=1.077)and the y-intercept(group merged)from the MU recruitment threshold versus derecruitment threshold relationship(bout 1 vs.bout 2=7.10±14.20 vs.0.73±16.24,p=0.029,d=0.513)at 50%MVIC were significantly different between two bouts.However,other muscle damage markers did not show any CL-RBE in both muscle groups.Therefore,despite changes in muscle excitation and MU firing behavior,our results do not support the existence of CL-RBE on BB and FDI muscles.展开更多
Functional electrical stimulation delivered early after injury to the proximal nerve stump has been proposed as a therapeutic approach for enhancing the speed and specificity of axonal regeneration following nerve inj...Functional electrical stimulation delivered early after injury to the proximal nerve stump has been proposed as a therapeutic approach for enhancing the speed and specificity of axonal regeneration following nerve injury. In this study, the injured oculomotor nerve was stimulated functionally by an implantable electrode. Electromyographic monitoring of the motor unit potential of the inferior oblique muscle was conducted for 12 weeks in two injury groups, one with and one without electric stimulation. The results revealed that, at 2, 4, 6, 8 weeks after functional electric stimulation of the injured oculomotor nerve, motor unit potentials significantly increased, such that amplitude was longer and spike duration gradually shortened. These findings indicate that the injured oculomotor nerve has the potential for regeneration and repair, but this ability is not sufficient for full functional recovery to occur. Importantly, the current results indicated that recovery and regeneration of the injured oculomotor nerve can be promoted with functional electrical stimulation.展开更多
Purpose:This study examined potential differences in strength,muscle morphology,and motor unit(MU)behavior of the abductor digiti minimi(ADM)between normal-fat(NF)and over-fat(OF)males.Methods:Dual-energy X-ray absorp...Purpose:This study examined potential differences in strength,muscle morphology,and motor unit(MU)behavior of the abductor digiti minimi(ADM)between normal-fat(NF)and over-fat(OF)males.Methods:Dual-energy X-ray absorptiometry assessed percent body fat(%BF).Ultrasonography determined muscle cross-sectional area(CSA),echo intensity(EI),and subcutaneous fat(s FAT).MU behavior was assessed during isometric muscle actions at 50%of maximal voluntary contraction(MVC)by analyzing the y-intercepts and slopes for the MU action potential amplitude(MUAPAMP)vs.recruitment threshold(RT)relationships,the A and B terms for the mean firing rate(MFR)vs.RT relationships,and normalized electromyographic amplitude(N-EMGRMS).MU firing times and waveforms were validated with reconstruct-and-test and spike trigger average procedures.Results:%BF was greater for OF(25.70%±5.40%)than NF(16.50%±2.20%;p<0.001).MVC was greater for NF(27.13±7.16)N than OF([19.89±4.96]N;p=0.014).CSA was greater for NF(2.48±0.39)cm^(2)than OF([1.95±0.47]cm^(2);p=0.011).The y-intercepts for the MUAPAMPvs.RT relationships were greater for NF(0.283±0.254)m V than OF([-0.221±0.659]m V;p=0.004).The B terms for the MFR vs.RT relationships were greater for NF(-0.024±0.003)pps/%MVC than OF([-0.031±0.009]pps/%MVC;p=0.038).N-EMGRMSwas similar between groups(p=0.463).Conclusion:Maximal strength,muscle size,and MU recruitment and firing rate patterns for a non-weight bearing muscle differed between normal-fat and over-fat males.展开更多
This study assessed both motor unit population and firing behavior alterations of the first dorsal interosseous(FDI)muscle in six individuals with stroke,toward better understanding muscle weakness after stroke.Motor ...This study assessed both motor unit population and firing behavior alterations of the first dorsal interosseous(FDI)muscle in six individuals with stroke,toward better understanding muscle weakness after stroke.Motor unit population was estimated using the F wave based motor unit number estimation(MUNE)technique,while motor unit firing behavior was extracted through high-density surface electromyography(EMG)decomposition.Inspection of individual subject data disclosed different patterns of motor unit changes associated with post-stroke weakness.Four subjects concurrently demonstrated loss of functioning motor units and reduced motor unit firing rates in the paretic muscle compared with the contralateral muscle.For the remaining two subjects,one showed remarkable decrease of motor unit number but similar firing rates in the paretic muscle,while on the contrary the other subject demonstrated remarkable decrease in motor unit firing rates but similar motor unit number counts in the paretic muscle,compared with the contralateral muscle.Findings from this study add insights in understanding complexity of post-stroke muscle weakness and help development of appropriate in-terventions in stroke rehabilitation targeting specific motor unit impairment.展开更多
Reconstructing limb function represents a shared goal between researchers and amputees.However,the development of human-machine interfaces for decoding multi-degree-of-freedom(multi-DoF)movements remains challenging d...Reconstructing limb function represents a shared goal between researchers and amputees.However,the development of human-machine interfaces for decoding multi-degree-of-freedom(multi-DoF)movements remains challenging due to muscle crosstalk,co-activation,and incomplete extraction of motor unit(MU)activities in surface electromyography(sEMG)signals.To address these issues,this study proposes an enhanced neural-driven musculoskeletal model(MM)by integrating MU classification into the decoding process.Six sequential two-DoF movement tasks were designed and a classification framework containing eight task-specific separation matrices was established based on the selective activation of the MUs.The interference between multi-DoF movements was significantly reduced by refining the separation matrices,which effectively removed the MUs co-activated by multiple DoFs.The refined separation matrices were used to derive neural drives,which were subsequently integrated into the proposed four-DoF MM,and the accuracy loss resulting from reduced MU counts was compensated through the iterative optimization of physiological parameters.The proposed method was evaluated by an offline experiment involving 13 participants,and then compared with both classical neural-driven and non-negative matrix factorization(NMF)-driven MMs.Results demonstrated significant improvements in both correlation coefficient and normalized root mean square error,especially in complex four-DoF movement tasks.This study offers a novel and biologically grounded decoding strategy that enhances multi-DoF movement prediction and provides a promising direction for advanced prosthetic control.展开更多
Skeletal muscles are essential parts of the human motor system and are mainly regulated by motor units(MUs)through the nervous system.As a widely used noninvasive measurement of MUs,surface EMG cannot obtain in-depth ...Skeletal muscles are essential parts of the human motor system and are mainly regulated by motor units(MUs)through the nervous system.As a widely used noninvasive measurement of MUs,surface EMG cannot obtain in-depth spatial information on MUs.Ultrafast ultrasound(UUS)can measure the mechanical response of MUs from muscle morphology with image sequences.This research proposed a blind source separation method with enhanced interpretability for decoding ultrasound image sequences to obtain the mechanical response of MUs.In particular,the spatiotemporal data were decomposed using non-negative matrix factorization(NMF).Then,the spatial components’multiple probability density functions were obtained using a parametric self-fitting function.The proposed algorithm,called NMF-stICA,was validated on ten groups of computational simulation datasets.The accuracies of the obtained spatial and temporal components were 87.26%±2.18%and 85.13%±1.83%,respectively.Further,a dynamic ultrasound phantom experiment was performed,and all the potential spatial components were correctly decoded.Additionally,isometric contraction human experiments were conducted on the biceps muscle of eight subjects with simultaneous acquisition of UUS and intramuscular electromyography(iEMG).The results showed that the rate of agreement was 58.71%,comparing the decoded components with the firing pattern of iEMG.The proposed decoding method can get precise spatial position and the firing pattern of the MUs in the skeletal muscle.This might help to study the neuromechanical properties of MUs and localize disease in specific muscle regions.展开更多
目的:探讨变频相位干涉电场刺激(temporal interference electrical fields stimulation,TIs)对人体肌肉力量和神经肌肉募集能力的影响。方法:16名健康成年人受试者均完成两次测试,两次测试至少间隔48小时。两次测试仅干预方案不同,分...目的:探讨变频相位干涉电场刺激(temporal interference electrical fields stimulation,TIs)对人体肌肉力量和神经肌肉募集能力的影响。方法:16名健康成年人受试者均完成两次测试,两次测试至少间隔48小时。两次测试仅干预方案不同,分别为变频TIs真刺激和假刺激,刺激目标靶区均为左侧初级运动皮层,测试任务为手部第一骨间背侧肌的最大自主收缩(maximal voluntary contraction,MVC),包括3 s和20 s两种条件。在采集20 s MVC的同时采集表面肌电信号,并利用表面肌电信号分解技术分析。结果:3 s MVC的峰值肌力表现出时间(干预前后)与干预条件(真假刺激)的显著交互作用(P<0.05);与刺激前相比,变频TIs后3 s MVC的峰值肌力显著提升,而假刺激后下降。20 s MVC的峰值肌电振幅表现出时间与干预条件的显著交互作用(P<0.05);与刺激前相比,变频TIs后峰值肌电振幅增加而假刺激后下降。结论:变频TIs能够有效增强3 s MVC的峰值肌力和20 s MVC时的运动单位同步放电水平,具有显著提升运动表现的潜力。展开更多
基金Supported by the Italian MIUR PRIN Grant year 2006,# 2006062332_002
文摘BACKGROUND：Amyotrophic lateral sclerosis （ALS） is the most common of all the motor neuron diseases and the absence of a biologic marker has made both diagnosis and tracking evolution of the disease difficult, Electrodiagnostic tests play a fundamental role in quantifying pathological changes in the motor unit pool.OBJECTIVE：We assessed distal-proximal Motor Unit （MU） loss and changes using the method of motor unit number estimation （MUNE）.DESIGN, TIME AND SETTING：A case-control study was performed at the Department of Neuroscience, Pisa University Medical School, Italy from December 1999 to November 2009. PARTICIPANTS：A total of 50 ALS patients were recruited, 30 males：mean age （59.6 ± 13.3） years; 20 females：mean age （63.9 ± 11.7） years; range （30-82） years; all patients had probable or definite ALS. Thirty healthy volunteers were recruited from department staffs, including 20 males and 10 females; mean age （57.7 ± 13.8） years served as controls.METHODS：MUNE was performed for both the biceps brachii and abductor digiti minimi muscles of the same side. The technique used relayed substantially on manual incremental stimulation of the motor nerve, known as the McComas technique （50 ms sweep duration, a gain of 2 mV/Div for M wave, 0.5 mV/Div for each step; filters 10-20 kHz）.MAIN OUTCOME MEASURES：MUNE results were measured.RESULTS：Functioning MU numbers, measured by MUNE, decreased in the biceps brachii and abductor digiti minimi muscles over the entire one-year follow-up period （one assessment every three months） compared with baseline determination, the rate of MU decrease was similar in both muscles, but steeper distally.CONCLUSION：MUNE is a feasible method for ALS patients both proximally and distally to track changes over time in muscle MUs during the disease＇s evolution.
文摘The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when the maximal level is achieved. The study included 110 participants. To assess the contractile characteristics of leg extensors, standardized equipment and standardized isometric test in sitting position with the angle of the knee joint of 125° were used. The participants were instructed to exert their maximal force as quickly as possible. Using descriptive statistics, cluster analysis and fitting the exponential model of the distribution of force of leg extensor motor units in the whole range of force generation is defined. The model has the following form： y = 0.2051e3.3855x, where y is the motor units force expressed in daN （decanewtons）, x is the time expressed in s （seconds）. It provides an understanding of the control of multivariate motor unit recruitment and distribution of their force during sports movements as well as training programming for the adoption of forms for conlrolling force distribution of motor units, the development of their maximum force and their involvement speed.
文摘To examine the contralateral repeated bout effect(CL-RBE)on muscle damage markers and motor unit(MU)control strategies,seventeen healthy adults performed two bouts of 60 eccentric contractions with elbow flexor(EF group;n=9)or index finger abductor(IA group;n=8)muscles,separated by 1 week.All participants randomly performed eccentric exercise on either the right or left arm or hand muscles,and muscle damage markers and submaximal trapezoid contraction tests were conducted pre,post,1-and 2-day post eccentric protocol.One week after the first bout,the same exercise protocol and measurements were performed on the contralateral muscles.Surface electromyographic(EMG)signals were collected from biceps brachii(BB)or first dorsal interosseous(FDI)during maximal and submaximal tests.The linear regression analyses were used to examine MU recruitment threshold versus mean firing rate and recruitment threshold versus derecruitment threshold relationships.EMG amplitude from BB(bout 1 vs.bout 2=65.71%±22.92%vs.43.05%±18.97%,p=0.015,d=1.077)and the y-intercept(group merged)from the MU recruitment threshold versus derecruitment threshold relationship(bout 1 vs.bout 2=7.10±14.20 vs.0.73±16.24,p=0.029,d=0.513)at 50%MVIC were significantly different between two bouts.However,other muscle damage markers did not show any CL-RBE in both muscle groups.Therefore,despite changes in muscle excitation and MU firing behavior,our results do not support the existence of CL-RBE on BB and FDI muscles.
基金the National Natural Science Foundation of China, No. 30571907International Science and Technology Cooperation Foundation by Shanghai Committee of Science and Technology, China, No. 10410711400
文摘Functional electrical stimulation delivered early after injury to the proximal nerve stump has been proposed as a therapeutic approach for enhancing the speed and specificity of axonal regeneration following nerve injury. In this study, the injured oculomotor nerve was stimulated functionally by an implantable electrode. Electromyographic monitoring of the motor unit potential of the inferior oblique muscle was conducted for 12 weeks in two injury groups, one with and one without electric stimulation. The results revealed that, at 2, 4, 6, 8 weeks after functional electric stimulation of the injured oculomotor nerve, motor unit potentials significantly increased, such that amplitude was longer and spike duration gradually shortened. These findings indicate that the injured oculomotor nerve has the potential for regeneration and repair, but this ability is not sufficient for full functional recovery to occur. Importantly, the current results indicated that recovery and regeneration of the injured oculomotor nerve can be promoted with functional electrical stimulation.
文摘Purpose:This study examined potential differences in strength,muscle morphology,and motor unit(MU)behavior of the abductor digiti minimi(ADM)between normal-fat(NF)and over-fat(OF)males.Methods:Dual-energy X-ray absorptiometry assessed percent body fat(%BF).Ultrasonography determined muscle cross-sectional area(CSA),echo intensity(EI),and subcutaneous fat(s FAT).MU behavior was assessed during isometric muscle actions at 50%of maximal voluntary contraction(MVC)by analyzing the y-intercepts and slopes for the MU action potential amplitude(MUAPAMP)vs.recruitment threshold(RT)relationships,the A and B terms for the mean firing rate(MFR)vs.RT relationships,and normalized electromyographic amplitude(N-EMGRMS).MU firing times and waveforms were validated with reconstruct-and-test and spike trigger average procedures.Results:%BF was greater for OF(25.70%±5.40%)than NF(16.50%±2.20%;p<0.001).MVC was greater for NF(27.13±7.16)N than OF([19.89±4.96]N;p=0.014).CSA was greater for NF(2.48±0.39)cm^(2)than OF([1.95±0.47]cm^(2);p=0.011).The y-intercepts for the MUAPAMPvs.RT relationships were greater for NF(0.283±0.254)m V than OF([-0.221±0.659]m V;p=0.004).The B terms for the MFR vs.RT relationships were greater for NF(-0.024±0.003)pps/%MVC than OF([-0.031±0.009]pps/%MVC;p=0.038).N-EMGRMSwas similar between groups(p=0.463).Conclusion:Maximal strength,muscle size,and MU recruitment and firing rate patterns for a non-weight bearing muscle differed between normal-fat and over-fat males.
基金NIDILRR RERC under 90REMMO001-01-00Taishan Scholar Project of Shandong Province.
文摘This study assessed both motor unit population and firing behavior alterations of the first dorsal interosseous(FDI)muscle in six individuals with stroke,toward better understanding muscle weakness after stroke.Motor unit population was estimated using the F wave based motor unit number estimation(MUNE)technique,while motor unit firing behavior was extracted through high-density surface electromyography(EMG)decomposition.Inspection of individual subject data disclosed different patterns of motor unit changes associated with post-stroke weakness.Four subjects concurrently demonstrated loss of functioning motor units and reduced motor unit firing rates in the paretic muscle compared with the contralateral muscle.For the remaining two subjects,one showed remarkable decrease of motor unit number but similar firing rates in the paretic muscle,while on the contrary the other subject demonstrated remarkable decrease in motor unit firing rates but similar motor unit number counts in the paretic muscle,compared with the contralateral muscle.Findings from this study add insights in understanding complexity of post-stroke muscle weakness and help development of appropriate in-terventions in stroke rehabilitation targeting specific motor unit impairment.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4700801)the National Natural Science Foundation of China(Grant No.52525504)the Emerging Frontiers Cultivation Program of Tianjin University Interdisciplinary Center。
文摘Reconstructing limb function represents a shared goal between researchers and amputees.However,the development of human-machine interfaces for decoding multi-degree-of-freedom(multi-DoF)movements remains challenging due to muscle crosstalk,co-activation,and incomplete extraction of motor unit(MU)activities in surface electromyography(sEMG)signals.To address these issues,this study proposes an enhanced neural-driven musculoskeletal model(MM)by integrating MU classification into the decoding process.Six sequential two-DoF movement tasks were designed and a classification framework containing eight task-specific separation matrices was established based on the selective activation of the MUs.The interference between multi-DoF movements was significantly reduced by refining the separation matrices,which effectively removed the MUs co-activated by multiple DoFs.The refined separation matrices were used to derive neural drives,which were subsequently integrated into the proposed four-DoF MM,and the accuracy loss resulting from reduced MU counts was compensated through the iterative optimization of physiological parameters.The proposed method was evaluated by an offline experiment involving 13 participants,and then compared with both classical neural-driven and non-negative matrix factorization(NMF)-driven MMs.Results demonstrated significant improvements in both correlation coefficient and normalized root mean square error,especially in complex four-DoF movement tasks.This study offers a novel and biologically grounded decoding strategy that enhances multi-DoF movement prediction and provides a promising direction for advanced prosthetic control.
基金supported by the National Natural Science Foundation of China(Grant Nos.52227808,52175023,52205024).
文摘Skeletal muscles are essential parts of the human motor system and are mainly regulated by motor units(MUs)through the nervous system.As a widely used noninvasive measurement of MUs,surface EMG cannot obtain in-depth spatial information on MUs.Ultrafast ultrasound(UUS)can measure the mechanical response of MUs from muscle morphology with image sequences.This research proposed a blind source separation method with enhanced interpretability for decoding ultrasound image sequences to obtain the mechanical response of MUs.In particular,the spatiotemporal data were decomposed using non-negative matrix factorization(NMF).Then,the spatial components’multiple probability density functions were obtained using a parametric self-fitting function.The proposed algorithm,called NMF-stICA,was validated on ten groups of computational simulation datasets.The accuracies of the obtained spatial and temporal components were 87.26%±2.18%and 85.13%±1.83%,respectively.Further,a dynamic ultrasound phantom experiment was performed,and all the potential spatial components were correctly decoded.Additionally,isometric contraction human experiments were conducted on the biceps muscle of eight subjects with simultaneous acquisition of UUS and intramuscular electromyography(iEMG).The results showed that the rate of agreement was 58.71%,comparing the decoded components with the firing pattern of iEMG.The proposed decoding method can get precise spatial position and the firing pattern of the MUs in the skeletal muscle.This might help to study the neuromechanical properties of MUs and localize disease in specific muscle regions.
文摘目的:探讨变频相位干涉电场刺激(temporal interference electrical fields stimulation,TIs)对人体肌肉力量和神经肌肉募集能力的影响。方法:16名健康成年人受试者均完成两次测试,两次测试至少间隔48小时。两次测试仅干预方案不同,分别为变频TIs真刺激和假刺激,刺激目标靶区均为左侧初级运动皮层,测试任务为手部第一骨间背侧肌的最大自主收缩(maximal voluntary contraction,MVC),包括3 s和20 s两种条件。在采集20 s MVC的同时采集表面肌电信号,并利用表面肌电信号分解技术分析。结果:3 s MVC的峰值肌力表现出时间(干预前后)与干预条件(真假刺激)的显著交互作用(P<0.05);与刺激前相比,变频TIs后3 s MVC的峰值肌力显著提升,而假刺激后下降。20 s MVC的峰值肌电振幅表现出时间与干预条件的显著交互作用(P<0.05);与刺激前相比,变频TIs后峰值肌电振幅增加而假刺激后下降。结论:变频TIs能够有效增强3 s MVC的峰值肌力和20 s MVC时的运动单位同步放电水平,具有显著提升运动表现的潜力。
