Bachelor in Physical Therapy (2007) and Masters in Human Movement Science (2010) from the University of Santa Catarina State. Obtained her Ph.D. in Biomechanics and Movement Science (2015) at the University of Delaware with concentration in Motor Control. During her doctoral studies (Nov/2013 - Jul/2015), worked as a visitor researcher in the Motor Control Lab at Penn State University. Studies theories of motor control and brain plasticity to deepen the understanding of mechanisms underlying upper limb function and rehabilitation. She has experience with the following topics: movement synergy, motor redundancy, movement variability, movement coordination of neurologic population. Supervisors: Dr. Mark Latash, Dr. John Scholz , Dr. Darcy Reisman (co-advisor), Dr. Susana Cristina Domonech, Dr. Marcio José dos Santos (co-advisor), and Dr. Noé Gomes Borges Júnio (co-advisor)
Muscular and joint injuries and localized pain can be occasioned during sports practice. Although... more Muscular and joint injuries and localized pain can be occasioned during sports practice. Although the reliability of palpation techniques (to evaluate muscle and joint tenderness) has improved and algometers have been developed1, they do not simulate the palpation technique and real time measurements are not possible. A new pressure algometer to determine pressure pain thresholds in real time has been developed, to be used in diagnosis and injury treatment evaluation of athletes.
Highlights • Increase in upper limb function post task specific training in chronic stroke.• Moto... more Highlights • Increase in upper limb function post task specific training in chronic stroke.• Motor improvements were not accompanied by changes in white matter integrity.• Integrity in contralesional fibers predicted larger motor recovery in Responders.• Non-responders had more severe damage of transcallosal fibers than Responders.
BACKGROUND Analysis of sensorimotor synergies has been greatly advanced by the Uncontrolled Manif... more BACKGROUND Analysis of sensorimotor synergies has been greatly advanced by the Uncontrolled Manifold (UCM) approach. The UCM method is based on partitioning inter-trial variance displayed by elemental variables into 'good' (VUCM) and 'bad' (VORT) variability that, respectively, indicate maintenance or loss of task stability. In clinical populations, these indices can be used to investigate the strength, flexibility, stereotypy and agility of synergistic control. RESEARCH QUESTION How are synergies affected by neurological impairment in adults? Specifically, this study aimed to determine i) the impact of pathology on VUCM, VORT, and their ratio (synergy index); ii) the relationship between synergy indices and functional performance; iii) changes in anticipatory synergy adjustments (ASAs); and iv) the effects of interventions on synergies. METHODS Systematic review of UCM studies on adults with neurological impairment. RESULTS Most of the 17 studies had moderate to high quality scores in the adapted Critical Review Form and the UCM reporting quality checklist developed for this review. i) Most of the studies found reduced synergy indices for patients with Parkinson's disease (PD), olivo-ponto-cerebellar atrophy, multiple sclerosis and spinocerebellar degeneration, with variable levels of change in VUCM and VORT. Reduction in synergy indices was not as consistent for stroke, in three out of six studies it was unchanged. ii) Five of seven studies found no significant correlations between scores on motor function scales and UCM indices. iii) Seven studies consistently reported ASAs that are smaller in magnitude, delayed, or both, for patients compared to healthy controls. iv) Two studies reported increased synergy indices, either via increase in VUCM or decrease in VORT, after dopaminergic drugs for patients with PD. There were similar synergy indices but improved ASAs after deep brain stimulation for patients with PD. SIGNIFICANCE UCM can provide reliable and sensitive indicators of altered synergistic control in adults with neurological impairment.
Highlights - We provide the first functional brain data of grasping with a transplanted hand. - N... more Highlights - We provide the first functional brain data of grasping with a transplanted hand. - Normative grasp kinematics parallel normative grasp-selective fMRI responses. - Grasp recovers despite persistent low-level deficits and changes in motor cortex. - Grasp and its normative brain organization are restored after hand transplantation. ABSTRACT Hand loss can now be reversed through surgical transplantation years or decades after amputation. Remarkably, these patients come to use their new hand to skilfully grasp and manipulate objects. The brain mechanisms that make this possible are unknown. Here we test the hypothesis that the anterior intraparietal cortex (aIPC) – a multimodal region implicated in hand preshaping and error correction during grasping – plays a key role in this compensatory grasp control. Motion capture and fMRI are used to characterize hand kinematics and brain responses during visually guided grasping with a transplanted hand at 26 and 41 months post-transp...
The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS)... more The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses. The patients showed significantly lower maximal finger forces and a tendency toward slower force pulses. Enslaving was increased in MS, but only in the lateral fingers (index and little). Indices of multifinger synergies during steady-state force production were lower in MS, mainly due to the lower amount of intertrial variance that did not affect total force. Anticipatory synergy adjustments were significantly delayed in MS. The results show that MS leads to significant changes in multidigit synergies and feed-forward adjustments of the synergies prior to a quick action. The authors discuss possible contributions of subcortical structures to the impaired synergic control.
—We use an approach rooted in the recent theory of synergies to analyze possible co-variation bet... more —We use an approach rooted in the recent theory of synergies to analyze possible co-variation between two hypothetical control variables involved in finger force production based on the equilibrium-point (EP) hypothesis. These control variables are the referent coordinate (R) and apparent stiffness (C) of the finger. We tested a hypothesis that inter-trial co-variation in the {R; C} space during repeated, accurate force production trials stabilizes the fingertip force. This was expected to correspond to a relatively low amount of inter-trial variability affecting force and a high amount of variability keeping the force unchanged. We used the ''inverse piano " apparatus to apply small and smooth positional perturbations to fingers during force production tasks. Across trials, R and C showed strong co-variation with the data points lying close to a hyperbolic curve. Hyper-bolic regressions accounted for over 99% of the variance in the {R; C} space. Another analysis was conducted by ran-domizing the original {R; C} data sets and creating surro-gate data sets that were then used to compute predicted force values. The surrogate sets always showed much higher force variance compared to the actual data, thus reinforcing the conclusion that finger force control was organized in the {R; C} space, as predicted by the EP hypothesis, and involved co-variation in that space stabilizing total force.
We explored unintentional changes in forces during performance of constant and cyclic force-produ... more We explored unintentional changes in forces during performance of constant and cyclic force-production tasks (F-tasks) after visual feedback removal. Based on earlier studies, we expected all force parameters to drop exponentially with time. We also explored possible role of working memory in the force drop phenomena. Healthy subjects performed constant or cyclic isometric F-tasks with the index finger under visual feedback. The cyclic task was paced by a metronome. Removing visual feedback resulted in a consistent force drop in constant F-tasks and a qualitatively similar drift in the mean force in the cyclic F-task. Both were slow with characteristic times of about 10–20 s. In contrast, force amplitude in the cyclic F-task increased quickly (within 1–2 s). When the subjects were asked to stop producing force for 5 s after the visual feed- back disappeared and then resume force production, no downward force drift was seen in constant F-tasks, while in cyclic F-tasks, the drift of the mean force was present and an exaggerated increase in force amplitude was also observed. We conclude that while working memory limitations may influence cyclic F-tasks, their role in deter- mining the force drift in constant F-tasks is limited. The results of both experiments are interpreted within the referent configuration hypothesis supplemented with an idea of unintentional drift of referent coordinates (RC-back- coupling) induced by differences between the referent and actual body configurations.
—Our main goal was to test a hypothesis that transient changes in performance of a steady-state t... more —Our main goal was to test a hypothesis that transient changes in performance of a steady-state task would result in motor equivalence. We also estimated effects of visual feedback on the amount of reorganization of motor elements. Healthy subjects performed two variations of a four-finger pressing task requiring accurate production of total pressing force (F TOT) and total moment of force (M TOT). In the Jumping-Target task, a sequence of target jumps required transient changes in either F TOT or M TOT. In the Step-Perturbation task, the index finger was lifted by 1 cm for 0.5 s leading to a change in both F TOT and M TOT. Visual feedback could have been frozen for one of these two variables in both tasks. Deviations in the space of finger modes (hypothetical commands to individual fingers) were quantified in directions of unchanged F TOT and M TOT (motor equivalent – ME) and in directions that changed F TOT and M TOT (non-motor equivalence – nME). Both the ME and nME components increased when the performance changed. After transient target jumps leading to the same combination of F TOT and M TOT , the changes in finger modes had a large residual ME component with only a very small nME component. Without visual feedback, an increase in the nME component was observed without consistent changes in the ME component. Results from the Step-Perturbation task were qualitatively similar. These findings suggest that both external perturbations and purposeful changes in performance trigger a reorganization of elements of an abundant system, leading to large ME change. These results are consistent with the principle of motor abundance corroborating the idea that a family of solutions is facilitated to stabilize values of important performance variables. Published by Elsevier Ltd. on behalf of IBRO.
Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbati... more Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbation involve large changes in neural commands that do not affect salient performance variables, even during actions with the purpose to correct those salient variables. Consistency of the analyses of motor equivalence and variance analysis provides additional support for the idea of task-specific stability ensured at a neural level.
The concept of motor equivalent combinations of arm muscles, or M-modes, was investigated during ... more The concept of motor equivalent combinations of arm muscles, or M-modes, was investigated during reaching to insert a pointer into a cylindrical target with and without an elbow perturbation. Five M-modes across 15 arm/scapula muscles were identified by principal component analysis with factor extraction. The relationship between small changes in the M-modes and changes in the position/orientation of the pointer were investigated by linear regression analyses. The results revealed a motor equivalent organization of the M-modes for perturbed compared with non-perturbed reaches, both with respect to hand position and orientation, especially in the first 100-ms postperturbation. Similar findings were obtained for motor equivalence computed based on changes in the joint configuration, although the kinematically defined motor equivalence was stronger for pointer orientation. The results support the hypothesis that the nervous system organizes muscles into M-modes and flexibly scales M-mode activation to preserve stable values of variables directly related to performance success.
Eight subjects with carpal tunnel syndrome (CTS) (47.13 ± 7.83 years) and 8 matched controls (46.... more Eight subjects with carpal tunnel syndrome (CTS) (47.13 ± 7.83 years) and 8 matched controls (46.29 ± 7.27 years) manipulated a test object fitted with an accelerometer and force sensor, both before and after hand muscle fatigue. Grip force and object acceleration were recorded and used to calculate grip force control variables that included Grip Force Peak, Safety Margin, and Time to Grip Force Peak. Individuals with CTS exhibited a higher Safety Margin (p = .010) and longer Time to Peak of Grip Force (p = .012) than healthy controls during object manipulation. Once fatigued, both groups significantly decreased their grip force to perform the task (Grip Force Peak; p = .017 and Safety Margin; p < .001). Nevertheless, individuals with CTS maintained an unnecessarily high safety margin. Our results suggest that CTS can adversely affect how the central nervous system regulates grip force, which might aggravate the inflammatory process and exacerbate the symptoms of this disease.
The purpose of this study was to verify the validity of the flight and ground contact time measur... more The purpose of this study was to verify the validity of the flight and ground contact time measurement of a contact mat, SaltoBras (SB), comparing it to an oscilloscope (OS) and to a force plate (FP). For that, the SB was placed upon a FP. At first, four male and two female performed 15 jumps on the SB and the flight times were obtained. After, they performed six consecutive jumps and the ground contact times were obtained. SB software was valid in comparison with the OS, but underestimated the flight (~0.30 %) and ground contact (~1.01 %) time measurements when comparing it to the FP. Despite the differences, the error found between SB and FP was systematic, and two prediction equations were defined and added to the software for correction. The results suggest that SB is a valid instrument for the evaluation of vertical jump.
Changes in multifinger interaction and coordination in Parkinson's disease [PDF] [Full Text] [Abs... more Changes in multifinger interaction and coordination in Parkinson's disease [PDF] [Full Text] [Abstract] , production Equifinality and its violations in a redundant system: multifinger accurate force [PDF] [Full Text] [Abstract] , December 15, 2014; 112 (12): 3209-3218.
Thermally stable elastomeric composites based on ethylene–propylene–diene monomer (EPDM) and con-... more Thermally stable elastomeric composites based on ethylene–propylene–diene monomer (EPDM) and con- ducting polymer-modified carbon black (CPMCB) additives were produced by casting and crosslinked by compression molding. CPMCB represent a novel thermally stable conductive compound made via ‘‘in situ’’ deposition of intrinsically conducting polymers (ICP) such as polyaniline or polypyrrole on carbon black particles. Thermogravimetric analysis showed that the composites are thermally stable with no appreciable degradation at ca. 3008C. Incorporating CPMCB has been found to be advantageous to the processing of composites, as the presence of ICP lead to a better distribution of the filler within the rubber matrix, as confirmed by morphological analysis. These materials have a percolation threshold range of 5–10 phr depending on the formulation and electrical dc conductivity values in the range of 0.001 to 0.01 S cm -1 above the percolation threshold. A less pronounced reinforcing effect was observed in composites produced with ICP-modified additives in relation to those produced only with carbon black. The results obtained in this study show the feasibility of this method for producing stable, electrically conducting composites with elastomeric characteristics.
Biomedical Application based on Conducting Elastomeric Composites of Electricity. Thermally stabl... more Biomedical Application based on Conducting Elastomeric Composites of Electricity. Thermally stable elastomeric composites based on rubber EPDM (poly(ethylene-co-propylene-co-2-ethylidene-5-norbornene)) and additive carbon black modified with intrinsic conducting polymers (Eeonomer ®) were prepared by solution and crosslinked by molding to the compression. Thermogravimetric analyses (TGA) showed that the composites are thermally stable with loss of mass in ca. 300°C. The incorporation of the Eeonomer ® additives facilitated the processing of the composites, as it illustrates the morphologic analysis. These materials possess a percolation threshold around 5 the 10 phr, and values of electrical conductivity dc in the range of 10-3-10-1 S.cm-1 , above of the percolation threshold. The mechanical analyses was valued. The results gotten in this study show the versatility of the method adopted in producing conducting, electrically thermally stable composites and with elastomeric characteristics, used in the manufacture of an prototype of digit-pressure sensor. The prototype is constituted of three parts: the sensing element, the system of acquisition of signals and the mechanical system, connected to a microcomputer for acquisition of data. Introdução Uma das técnicas de avaliação clínica empregadas por profissionais da área da saúde é a dígito-pressão, a qual consiste em pressionar com a ponta dos dedos determinados pontos anatômicos. Esta técnica permite mapear áreas dolorosas, identificar pontos-gatilho, flacidez, contraturas, limitações da movimentação articular e das estruturas osteoarticulares. Estes são achados clínicos presentes no diagnóstico de disfunções como a disfunção têmporo-mandibular, lesões pós traumáticas, doenças inflamatórias (epicondilites, tendinites) e reumáticas (fibromialgia, síndrome de dor miofascial) 1-3. A técnica requer a participação do paciente que deve informar verbal ou fisicamente ao examinador que a palpação está provocando dor. Este procedimento, no entanto, não quantifica a dígito-pressão aplicada, provocando limitações como: ausência de protocolos padronizados impossibilitando discussão inter-examinadores e a subjetividade na determinação da evolução do paciente. O objetivo deste projeto é construir um protótipo de sensor resistivo com design específico e com propriedades eletro-mecânicas apropriadas para medição quantitativa da dígito-pressão. Para tanto, foi desenvolvido primeiramente um " elemento sensor " que consistiu de um compósito elastomérico condutor baseado em borracha de EPDM e aditivos de negro de fumo modificados com polímeros condutores intrínsecos (PCI). A otimização das
Muscular and joint injuries and localized pain can be occasioned during sports practice. Although... more Muscular and joint injuries and localized pain can be occasioned during sports practice. Although the reliability of palpation techniques (to evaluate muscle and joint tenderness) has improved and algometers have been developed1, they do not simulate the palpation technique and real time measurements are not possible. A new pressure algometer to determine pressure pain thresholds in real time has been developed, to be used in diagnosis and injury treatment evaluation of athletes.
Highlights • Increase in upper limb function post task specific training in chronic stroke.• Moto... more Highlights • Increase in upper limb function post task specific training in chronic stroke.• Motor improvements were not accompanied by changes in white matter integrity.• Integrity in contralesional fibers predicted larger motor recovery in Responders.• Non-responders had more severe damage of transcallosal fibers than Responders.
BACKGROUND Analysis of sensorimotor synergies has been greatly advanced by the Uncontrolled Manif... more BACKGROUND Analysis of sensorimotor synergies has been greatly advanced by the Uncontrolled Manifold (UCM) approach. The UCM method is based on partitioning inter-trial variance displayed by elemental variables into 'good' (VUCM) and 'bad' (VORT) variability that, respectively, indicate maintenance or loss of task stability. In clinical populations, these indices can be used to investigate the strength, flexibility, stereotypy and agility of synergistic control. RESEARCH QUESTION How are synergies affected by neurological impairment in adults? Specifically, this study aimed to determine i) the impact of pathology on VUCM, VORT, and their ratio (synergy index); ii) the relationship between synergy indices and functional performance; iii) changes in anticipatory synergy adjustments (ASAs); and iv) the effects of interventions on synergies. METHODS Systematic review of UCM studies on adults with neurological impairment. RESULTS Most of the 17 studies had moderate to high quality scores in the adapted Critical Review Form and the UCM reporting quality checklist developed for this review. i) Most of the studies found reduced synergy indices for patients with Parkinson's disease (PD), olivo-ponto-cerebellar atrophy, multiple sclerosis and spinocerebellar degeneration, with variable levels of change in VUCM and VORT. Reduction in synergy indices was not as consistent for stroke, in three out of six studies it was unchanged. ii) Five of seven studies found no significant correlations between scores on motor function scales and UCM indices. iii) Seven studies consistently reported ASAs that are smaller in magnitude, delayed, or both, for patients compared to healthy controls. iv) Two studies reported increased synergy indices, either via increase in VUCM or decrease in VORT, after dopaminergic drugs for patients with PD. There were similar synergy indices but improved ASAs after deep brain stimulation for patients with PD. SIGNIFICANCE UCM can provide reliable and sensitive indicators of altered synergistic control in adults with neurological impairment.
Highlights - We provide the first functional brain data of grasping with a transplanted hand. - N... more Highlights - We provide the first functional brain data of grasping with a transplanted hand. - Normative grasp kinematics parallel normative grasp-selective fMRI responses. - Grasp recovers despite persistent low-level deficits and changes in motor cortex. - Grasp and its normative brain organization are restored after hand transplantation. ABSTRACT Hand loss can now be reversed through surgical transplantation years or decades after amputation. Remarkably, these patients come to use their new hand to skilfully grasp and manipulate objects. The brain mechanisms that make this possible are unknown. Here we test the hypothesis that the anterior intraparietal cortex (aIPC) – a multimodal region implicated in hand preshaping and error correction during grasping – plays a key role in this compensatory grasp control. Motion capture and fMRI are used to characterize hand kinematics and brain responses during visually guided grasping with a transplanted hand at 26 and 41 months post-transp...
The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS)... more The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses. The patients showed significantly lower maximal finger forces and a tendency toward slower force pulses. Enslaving was increased in MS, but only in the lateral fingers (index and little). Indices of multifinger synergies during steady-state force production were lower in MS, mainly due to the lower amount of intertrial variance that did not affect total force. Anticipatory synergy adjustments were significantly delayed in MS. The results show that MS leads to significant changes in multidigit synergies and feed-forward adjustments of the synergies prior to a quick action. The authors discuss possible contributions of subcortical structures to the impaired synergic control.
—We use an approach rooted in the recent theory of synergies to analyze possible co-variation bet... more —We use an approach rooted in the recent theory of synergies to analyze possible co-variation between two hypothetical control variables involved in finger force production based on the equilibrium-point (EP) hypothesis. These control variables are the referent coordinate (R) and apparent stiffness (C) of the finger. We tested a hypothesis that inter-trial co-variation in the {R; C} space during repeated, accurate force production trials stabilizes the fingertip force. This was expected to correspond to a relatively low amount of inter-trial variability affecting force and a high amount of variability keeping the force unchanged. We used the ''inverse piano " apparatus to apply small and smooth positional perturbations to fingers during force production tasks. Across trials, R and C showed strong co-variation with the data points lying close to a hyperbolic curve. Hyper-bolic regressions accounted for over 99% of the variance in the {R; C} space. Another analysis was conducted by ran-domizing the original {R; C} data sets and creating surro-gate data sets that were then used to compute predicted force values. The surrogate sets always showed much higher force variance compared to the actual data, thus reinforcing the conclusion that finger force control was organized in the {R; C} space, as predicted by the EP hypothesis, and involved co-variation in that space stabilizing total force.
We explored unintentional changes in forces during performance of constant and cyclic force-produ... more We explored unintentional changes in forces during performance of constant and cyclic force-production tasks (F-tasks) after visual feedback removal. Based on earlier studies, we expected all force parameters to drop exponentially with time. We also explored possible role of working memory in the force drop phenomena. Healthy subjects performed constant or cyclic isometric F-tasks with the index finger under visual feedback. The cyclic task was paced by a metronome. Removing visual feedback resulted in a consistent force drop in constant F-tasks and a qualitatively similar drift in the mean force in the cyclic F-task. Both were slow with characteristic times of about 10–20 s. In contrast, force amplitude in the cyclic F-task increased quickly (within 1–2 s). When the subjects were asked to stop producing force for 5 s after the visual feed- back disappeared and then resume force production, no downward force drift was seen in constant F-tasks, while in cyclic F-tasks, the drift of the mean force was present and an exaggerated increase in force amplitude was also observed. We conclude that while working memory limitations may influence cyclic F-tasks, their role in deter- mining the force drift in constant F-tasks is limited. The results of both experiments are interpreted within the referent configuration hypothesis supplemented with an idea of unintentional drift of referent coordinates (RC-back- coupling) induced by differences between the referent and actual body configurations.
—Our main goal was to test a hypothesis that transient changes in performance of a steady-state t... more —Our main goal was to test a hypothesis that transient changes in performance of a steady-state task would result in motor equivalence. We also estimated effects of visual feedback on the amount of reorganization of motor elements. Healthy subjects performed two variations of a four-finger pressing task requiring accurate production of total pressing force (F TOT) and total moment of force (M TOT). In the Jumping-Target task, a sequence of target jumps required transient changes in either F TOT or M TOT. In the Step-Perturbation task, the index finger was lifted by 1 cm for 0.5 s leading to a change in both F TOT and M TOT. Visual feedback could have been frozen for one of these two variables in both tasks. Deviations in the space of finger modes (hypothetical commands to individual fingers) were quantified in directions of unchanged F TOT and M TOT (motor equivalent – ME) and in directions that changed F TOT and M TOT (non-motor equivalence – nME). Both the ME and nME components increased when the performance changed. After transient target jumps leading to the same combination of F TOT and M TOT , the changes in finger modes had a large residual ME component with only a very small nME component. Without visual feedback, an increase in the nME component was observed without consistent changes in the ME component. Results from the Step-Perturbation task were qualitatively similar. These findings suggest that both external perturbations and purposeful changes in performance trigger a reorganization of elements of an abundant system, leading to large ME change. These results are consistent with the principle of motor abundance corroborating the idea that a family of solutions is facilitated to stabilize values of important performance variables. Published by Elsevier Ltd. on behalf of IBRO.
Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbati... more Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbation involve large changes in neural commands that do not affect salient performance variables, even during actions with the purpose to correct those salient variables. Consistency of the analyses of motor equivalence and variance analysis provides additional support for the idea of task-specific stability ensured at a neural level.
The concept of motor equivalent combinations of arm muscles, or M-modes, was investigated during ... more The concept of motor equivalent combinations of arm muscles, or M-modes, was investigated during reaching to insert a pointer into a cylindrical target with and without an elbow perturbation. Five M-modes across 15 arm/scapula muscles were identified by principal component analysis with factor extraction. The relationship between small changes in the M-modes and changes in the position/orientation of the pointer were investigated by linear regression analyses. The results revealed a motor equivalent organization of the M-modes for perturbed compared with non-perturbed reaches, both with respect to hand position and orientation, especially in the first 100-ms postperturbation. Similar findings were obtained for motor equivalence computed based on changes in the joint configuration, although the kinematically defined motor equivalence was stronger for pointer orientation. The results support the hypothesis that the nervous system organizes muscles into M-modes and flexibly scales M-mode activation to preserve stable values of variables directly related to performance success.
Eight subjects with carpal tunnel syndrome (CTS) (47.13 ± 7.83 years) and 8 matched controls (46.... more Eight subjects with carpal tunnel syndrome (CTS) (47.13 ± 7.83 years) and 8 matched controls (46.29 ± 7.27 years) manipulated a test object fitted with an accelerometer and force sensor, both before and after hand muscle fatigue. Grip force and object acceleration were recorded and used to calculate grip force control variables that included Grip Force Peak, Safety Margin, and Time to Grip Force Peak. Individuals with CTS exhibited a higher Safety Margin (p = .010) and longer Time to Peak of Grip Force (p = .012) than healthy controls during object manipulation. Once fatigued, both groups significantly decreased their grip force to perform the task (Grip Force Peak; p = .017 and Safety Margin; p < .001). Nevertheless, individuals with CTS maintained an unnecessarily high safety margin. Our results suggest that CTS can adversely affect how the central nervous system regulates grip force, which might aggravate the inflammatory process and exacerbate the symptoms of this disease.
The purpose of this study was to verify the validity of the flight and ground contact time measur... more The purpose of this study was to verify the validity of the flight and ground contact time measurement of a contact mat, SaltoBras (SB), comparing it to an oscilloscope (OS) and to a force plate (FP). For that, the SB was placed upon a FP. At first, four male and two female performed 15 jumps on the SB and the flight times were obtained. After, they performed six consecutive jumps and the ground contact times were obtained. SB software was valid in comparison with the OS, but underestimated the flight (~0.30 %) and ground contact (~1.01 %) time measurements when comparing it to the FP. Despite the differences, the error found between SB and FP was systematic, and two prediction equations were defined and added to the software for correction. The results suggest that SB is a valid instrument for the evaluation of vertical jump.
Changes in multifinger interaction and coordination in Parkinson's disease [PDF] [Full Text] [Abs... more Changes in multifinger interaction and coordination in Parkinson's disease [PDF] [Full Text] [Abstract] , production Equifinality and its violations in a redundant system: multifinger accurate force [PDF] [Full Text] [Abstract] , December 15, 2014; 112 (12): 3209-3218.
Thermally stable elastomeric composites based on ethylene–propylene–diene monomer (EPDM) and con-... more Thermally stable elastomeric composites based on ethylene–propylene–diene monomer (EPDM) and con- ducting polymer-modified carbon black (CPMCB) additives were produced by casting and crosslinked by compression molding. CPMCB represent a novel thermally stable conductive compound made via ‘‘in situ’’ deposition of intrinsically conducting polymers (ICP) such as polyaniline or polypyrrole on carbon black particles. Thermogravimetric analysis showed that the composites are thermally stable with no appreciable degradation at ca. 3008C. Incorporating CPMCB has been found to be advantageous to the processing of composites, as the presence of ICP lead to a better distribution of the filler within the rubber matrix, as confirmed by morphological analysis. These materials have a percolation threshold range of 5–10 phr depending on the formulation and electrical dc conductivity values in the range of 0.001 to 0.01 S cm -1 above the percolation threshold. A less pronounced reinforcing effect was observed in composites produced with ICP-modified additives in relation to those produced only with carbon black. The results obtained in this study show the feasibility of this method for producing stable, electrically conducting composites with elastomeric characteristics.
Biomedical Application based on Conducting Elastomeric Composites of Electricity. Thermally stabl... more Biomedical Application based on Conducting Elastomeric Composites of Electricity. Thermally stable elastomeric composites based on rubber EPDM (poly(ethylene-co-propylene-co-2-ethylidene-5-norbornene)) and additive carbon black modified with intrinsic conducting polymers (Eeonomer ®) were prepared by solution and crosslinked by molding to the compression. Thermogravimetric analyses (TGA) showed that the composites are thermally stable with loss of mass in ca. 300°C. The incorporation of the Eeonomer ® additives facilitated the processing of the composites, as it illustrates the morphologic analysis. These materials possess a percolation threshold around 5 the 10 phr, and values of electrical conductivity dc in the range of 10-3-10-1 S.cm-1 , above of the percolation threshold. The mechanical analyses was valued. The results gotten in this study show the versatility of the method adopted in producing conducting, electrically thermally stable composites and with elastomeric characteristics, used in the manufacture of an prototype of digit-pressure sensor. The prototype is constituted of three parts: the sensing element, the system of acquisition of signals and the mechanical system, connected to a microcomputer for acquisition of data. Introdução Uma das técnicas de avaliação clínica empregadas por profissionais da área da saúde é a dígito-pressão, a qual consiste em pressionar com a ponta dos dedos determinados pontos anatômicos. Esta técnica permite mapear áreas dolorosas, identificar pontos-gatilho, flacidez, contraturas, limitações da movimentação articular e das estruturas osteoarticulares. Estes são achados clínicos presentes no diagnóstico de disfunções como a disfunção têmporo-mandibular, lesões pós traumáticas, doenças inflamatórias (epicondilites, tendinites) e reumáticas (fibromialgia, síndrome de dor miofascial) 1-3. A técnica requer a participação do paciente que deve informar verbal ou fisicamente ao examinador que a palpação está provocando dor. Este procedimento, no entanto, não quantifica a dígito-pressão aplicada, provocando limitações como: ausência de protocolos padronizados impossibilitando discussão inter-examinadores e a subjetividade na determinação da evolução do paciente. O objetivo deste projeto é construir um protótipo de sensor resistivo com design específico e com propriedades eletro-mecânicas apropriadas para medição quantitativa da dígito-pressão. Para tanto, foi desenvolvido primeiramente um " elemento sensor " que consistiu de um compósito elastomérico condutor baseado em borracha de EPDM e aditivos de negro de fumo modificados com polímeros condutores intrínsecos (PCI). A otimização das
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