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1.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 36(6): 1048-1054, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31875382

RESUMO

Artificial prosthesis is an important tool to help amputees to gain or partially obtain abled human limb functions. Compared with traditional prosthesis which is only for decoration or merely has feedforward control channel, the perception and feedback function of prosthesis is an important guarantee for its normal use and self-safety. And this includes the information of position, force, texture, roughness, temperature and so on. This paper mainly summarizes the development and current status of artificial prostheses in the field of perception and feedback technology in recent years, which is derived from two aspects: the recognition way of perception signals and the feedback way of perception signals. Among the part of recognition way of perception signals, the current commonly adopted sensors related to perception information acquisition and their application status in prosthesis are overviewed. Additionally, from the aspects of force feedback stimulation, invasive/non-invasive electrical stimulation, and vibration stimulation, the feedback methods of perception signals are summarized and analyzed. Finally, some problems existing in the perception and feedback technology of artificial prosthesis are proposed, and their development trends are also prospected.


Assuntos
Implantação de Prótese , Amputados , Membros Artificiais , Retroalimentação Sensorial , Humanos , Desenho de Prótese
2.
PLoS Comput Biol ; 15(10): e1007371, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31671096

RESUMO

Dancing and playing music require people to coordinate actions with auditory rhythms. In laboratory perception-action coordination tasks, people are asked to synchronize taps with a metronome. When synchronizing with a metronome, people tend to anticipate stimulus onsets, tapping slightly before the stimulus. The anticipation tendency increases with longer stimulus periods of up to 3500ms, but is less pronounced in trained individuals like musicians compared to non-musicians. Furthermore, external factors influence the timing of tapping. These factors include the presence of auditory feedback from one's own taps, the presence of a partner performing coordinated joint tapping, and transmission latencies (TLs) between coordinating partners. Phenomena like the anticipation tendency can be explained by delay-coupled systems, which may be inherent to the sensorimotor system during perception-action coordination. Here we tested whether a dynamical systems model based on this hypothesis reproduces observed patterns of human synchronization. We simulated behavior with a model consisting of an oscillator receiving its own delayed activity as input. Three simulation experiments were conducted using previously-published behavioral data from 1) simple tapping, 2) two-person alternating beat-tapping, and 3) two-person alternating rhythm-clapping in the presence of a range of constant auditory TLs. In Experiment 1, our model replicated the larger anticipation observed for longer stimulus intervals and adjusting the amplitude of the delayed feedback reproduced the difference between musicians and non-musicians. In Experiment 2, by connecting two models we replicated the smaller anticipation observed in human joint tapping with bi-directional auditory feedback compared to joint tapping without feedback. In Experiment 3, we varied TLs between two models alternately receiving signals from one another. Results showed reciprocal lags at points of alternation, consistent with behavioral patterns. Overall, our model explains various anticipatory behaviors, and has potential to inform theories of adaptive human synchronization.


Assuntos
Estimulação Acústica/métodos , Percepção Auditiva/fisiologia , Percepção do Tempo/fisiologia , Ciclos de Atividade , Antecipação Psicológica/fisiologia , Ciências Biocomportamentais , Simulação por Computador , Retroalimentação , Retroalimentação Sensorial/fisiologia , Humanos , Música , Periodicidade , Desempenho Psicomotor
3.
Hum Mov Sci ; 68: 102525, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31731210

RESUMO

Prior work demonstrates that humans spontaneously synchronize their head and trunk kinematics to a broad range of driving frequencies of perceived mediolateral motion prescribed using optical flow. Using a closed-loop visuomotor error augmentation task in an immersive virtual environment, we sought to understand whether unifying visual with vestibular and somatosensory feedback is a control goal during human walking, at least in the context of head and trunk stabilization. We hypothesized that humans would minimize visual errors during walking - i.e., those between the visual perception of movement and actual movement of the trunk. We found that subjects did not minimize errors between the visual perception of movement and actual movement of the head and trunk. Rather, subjects increased mediolateral trunk range of motion in response to error-augmented optical flow with positive feedback gains. Our results are more consistent with our alternative hypothesis - that visual feedback can override other sensory modalities and independently compel adjustments in head and trunk position. Also, aftereffects following exposure to error-augmented optical flow included longer, narrower steps and reduced mediolateral postural sway, particularly in response to larger amplitude positive feedback gains. Our results allude to a recalibration of head and trunk stabilization toward more tightly regulated postural control following exposure to error-augmented visual feedback. Lasting reductions in mediolateral postural sway may have implications for using error-augmented optical flow to enhance the integrity of walking balance control through training, for example in older adults.


Assuntos
Equilíbrio Postural/fisiologia , Percepção Visual/fisiologia , Caminhada/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Fenômenos Biomecânicos , Teste de Esforço/métodos , Retroalimentação Sensorial/fisiologia , Feminino , Movimentos da Cabeça/fisiologia , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Tronco/fisiologia , Vestíbulo do Labirinto/fisiologia , Adulto Jovem
4.
PLoS Comput Biol ; 15(11): e1007463, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31756199

RESUMO

External perturbation forces may compromise standing balance. The nervous system can intervene only after a delay greater than 100 ms, during which the body falls freely. With ageing, sensorimotor delays are prolonged, posing a critical threat to balance. We study a generic model of stabilisation with neural delays to understand how the organism should adapt to challenging balance conditions. The model suggests that ankle stiffness should be increased in anticipation of perturbations, for example by muscle co-contraction, so as to slow down body fall during the neural response delay. Increased ankle muscle co-contraction is indeed observed in young adults when standing in challenging balance conditions, and in older relative to young adults during normal stance. In parallel, the analysis of the model shows that increases in either stiffness or neural delay must be coordinated with decreases in spinal sensorimotor gains, otherwise the feedback itself becomes destabilizing. Accordingly, a decrease in spinal feedback is observed in challenging conditions, and with age-related increases in neural delay. These observations have been previously interpreted as indicating an increased reliance on cortical rather than spinal control of balance, despite the fact that cortical responses have a longer latency. Our analysis challenges this interpretation by showing that these observations are consistent with a functional coadaptation of spinal feedback gains to functional changes in stiffness and neural delay.


Assuntos
Tornozelo/fisiologia , Equilíbrio Postural/fisiologia , Adaptação Fisiológica/fisiologia , Eletromiografia , Retroalimentação , Retroalimentação Sensorial/fisiologia , Humanos , Modelos Biológicos , Modelos Teóricos , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Postura/fisiologia , Posição Ortostática
5.
J Electromyogr Kinesiol ; 49: 102361, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31605889

RESUMO

We investigate whether visual feedback on the spatial distribution of upper trapezius muscle activity can prolong time to task failure of sustained shoulder abduction. Surface electromyographic signals were acquired with a 13x5 grid of high-density electromyography (HDEMG) electrodes from the right upper trapezius muscle of 12 healthy volunteers as they performed sustained isometric shoulder abduction at 20% of their maximum voluntary contraction torque (MVC) until volitional exhaustion. Data were collected in two sessions; one with HDEMG visual feedback on the spatial distribution of upper trapezius activity and one without feedback. Although the HDEMG amplitude maps could be voluntarily modified by the participants during the feedback condition (significant shift in the barycenter of activity towards the cranial direction, P = 0.038), this did not influence endurance time (total endurance time with HDEMG feedback: 149.01 ±â€¯77.07 s, no feedback 141.74 ±â€¯60.93 s, P = 0.532). Future studies should assess whether endurance performance can be enhanced by allowing changes in arm position during the task (changing fiber tension-length relationships), by providing a more individual motor strategy, and/or by manipulating the colours used for the HDEMG maps (lighter colours for higher contraction intensities).


Assuntos
Retroalimentação Sensorial , Contração Isométrica , Desempenho Psicomotor , Músculos Superficiais do Dorso/fisiologia , Adulto , Eletromiografia , Feminino , Humanos , Masculino , Movimento , Tempo de Reação , Ombro/fisiologia , Torque
6.
PLoS Biol ; 17(10): e3000469, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31613874

RESUMO

Newly learned motor skills are initially labile and then consolidated to permit retention. The circuits that enable the consolidation of motor memories remain uncertain. Most work to date has focused on primary motor cortex, and although there is ample evidence of learning-related plasticity in motor cortex, direct evidence for its involvement in memory consolidation is limited. Learning-related plasticity is also observed in somatosensory cortex, and accordingly, it may also be involved in memory consolidation. Here, by using transcranial magnetic stimulation (TMS) to block consolidation, we report the first direct evidence that plasticity in somatosensory cortex participates in the consolidation of motor memory. Participants made movements to targets while a robot applied forces to the hand to alter somatosensory feedback. Immediately following adaptation, continuous theta-burst transcranial magnetic stimulation (cTBS) was delivered to block retention; then, following a 24-hour delay, which would normally permit consolidation, we assessed whether there was an impairment. It was found that when mechanical loads were introduced gradually to engage implicit learning processes, suppression of somatosensory cortex following training almost entirely eliminated retention. In contrast, cTBS to motor cortex following learning had little effect on retention at all; retention following cTBS to motor cortex was not different than following sham TMS stimulation. We confirmed that cTBS to somatosensory cortex interfered with normal sensory function and that it blocked motor memory consolidation and not the ability to retrieve a consolidated motor memory. In conclusion, the findings are consistent with the hypothesis that in adaptation learning, somatosensory cortex rather than motor cortex is involved in the consolidation of motor memory.


Assuntos
Potencial Evocado Motor/fisiologia , Retroalimentação Sensorial/fisiologia , Consolidação da Memória/fisiologia , Memória de Longo Prazo/fisiologia , Córtex Somatossensorial/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Córtex Motor/anatomia & histologia , Córtex Motor/fisiologia , Destreza Motora/fisiologia , Plasticidade Neuronal/fisiologia , Córtex Somatossensorial/anatomia & histologia , Estimulação Magnética Transcraniana
7.
Acta otorrinolaringol. esp ; 70(5): 251-257, sept.-oct. 2019. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-186367

RESUMO

Introducción y objetivos: La inadecuada retroalimentación auditiva en los niños con hipoacusia prelocutiva altera la articulación de consonantes y vocales. El propósito de esta investigación es comparar la producción de vocales en niños hipoacúsicos hispanohablantes con implante coclear o adaptación audioprotésica con niños normooyentes por medio del análisis acústico de las frecuencias formánticas y el espacio vocal. Método: Un total de 56 niños con hipoacusia prelocutiva (25 con implante coclear y 31 con audífonos) y 47 niños normooyentes participaron en el estudio. Los 2 primeros formantes (F1 y F2) de las 5 vocales del idioma español se midieron utilizando el programa Praat. Para analizar las diferencias entre los 3 grupos se aplicó el método ANOVA de análisis de la varianza y el test de Scheffé. También se calculó el área del espacio vocal. Resultados: El valor medio del F1 en todas las vocales no mostró diferencias significativas en los 3 grupos de niños. Para las vocales /i/, /o/ y /u/ el valor medio del F2 fue significativamente diferente entre los 2 grupos de niños hipoacúsicos y el grupo de niños normooyentes. Conclusión: Ambos grupos de niños con hipoacusia prelocutiva tienden a presentar sutiles desviaciones en la articulación de las vocales que pueden ser analizadas mediante un programa de análisis acústico


Introduction and objectives: Inadequate auditory feedback in prelingually deaf children alters the articulation of consonants and vowels. The purpose of this investigation was to compare vowel production in Spanish-speaking deaf children with cochlear implantation, and with hearing-aids with normal-hearing children by means of acoustic analysis of formant frequencies and vowel space. Methods: A total of 56 prelingually deaf children (25 with cochlear implants and 31 wearing hearing-aids) and 47 normal-hearing children participated. The first 2 formants (F1 and F2) of the five Spanish vowels were measured using Praat software. One-way analysis of variance (ANOVA) and post hoc Scheffé test were applied to analyze the differences between the 3 groups. The surface area of the vowel space was also calculated. Results: The mean value of F1 in all vowels was not significantly different between the 3 groups. For vowels /i/, /o/ and /u/, the mean value of F2 was significantly different between the 2 groups of deaf children and their normal-hearing peers. Conclusion: Both prelingually hearing-impaired groups tended toward subtle deviations in the articulation of vowels that could be analyzed using an objective acoustic analysis programme


Assuntos
Humanos , Masculino , Feminino , Pré-Escolar , Criança , Transtornos da Articulação/etiologia , Implantes Cocleares , Auxiliares de Audição , Perda Auditiva/complicações , Pessoas com Deficiência Auditiva , Fonética , Transtornos da Articulação/fisiopatologia , Retroalimentação Sensorial , Perda Auditiva/fisiopatologia , Perda Auditiva/reabilitação , Acústica da Fala , Medida da Produção da Fala , Qualidade da Voz
8.
Nat Med ; 25(9): 1356-1363, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31501600

RESUMO

Conventional leg prostheses do not convey sensory information about motion or interaction with the ground to above-knee amputees, thereby reducing confidence and walking speed in the users that is associated with high mental and physical fatigue1-4. The lack of physiological feedback from the remaining extremity to the brain also contributes to the generation of phantom limb pain from the missing leg5,6. To determine whether neural sensory feedback restoration addresses these issues, we conducted a study with two transfemoral amputees, implanted with four intraneural stimulation electrodes7 in the remaining tibial nerve (ClinicalTrials.gov identifier NCT03350061). Participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. These sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. We found that walking speed and self-reported confidence increased while mental and physical fatigue decreased for both participants during neural sensory feedback compared to the no stimulation trials. Furthermore, participants exhibited reduced phantom limb pain with neural sensory feedback. The results from these proof-of-concept cases provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.


Assuntos
Amputados/reabilitação , Membros Artificiais , Joelho/fisiopatologia , Membro Fantasma/prevenção & controle , Adulto , Fenômenos Biomecânicos , Retroalimentação Sensorial , Humanos , Joelho/inervação , Masculino , Pessoa de Meia-Idade , Membro Fantasma/fisiopatologia , Velocidade de Caminhada/fisiologia
9.
Gait Posture ; 74: 135-141, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31522106

RESUMO

INTRODUCTION: The main role of the upper limb is to position the hand in order to carry out varied activities requiring coordinated multi-joint movement, which requires mobility and stability at the glenohumeral joint. This is made possible by the interaction between active and passive structures as well as the integration of information coming from multiple systems. This interaction can be compromised by factors such as muscle fatigue and lack of visual feedback, leading to decreased performance. Several studies have investigated their isolated effect without looking at their combined effect. OBJECTIVE: To measure the specific and the combined effects of shoulder muscles fatigue and of lack of visual feedback on shoulder motor control during a reaching task with the arm in an elevated position. METHODS: 60 healthy participants were randomly assigned to one of four experimental groups: 1) control with visual feedback; 2) control without visual feedback; 3) fatigue with visual feedback; 4) fatigue without visual feedback. Subjects had to perform 10 trials of a reaching task in the KINARM robotic arm. Kinematic variables of interest were time taken to complete the task, final error, initial angle of deviation and area under curve. Non-parametric ANOVAs were used. RESULTS: Analyses showed that there were statistically significant differences (p < 0,01) for the time taken to complete the task (1.15 s compared to 0.70 s), the area under the curve (0.015m2 compared to 0.009m2) and the final error (0.025 m compared to 0,011 m) between those who had visual feedback and those who did not. No statistically significant fatigue or feedback X fatigue interaction effects were found for all kinematic variables. CONCLUSION: Findings show that lack of visual feedback had an impact on the reaching task performance while fatigue did not. In addition, fatigue did not increase the effect of the lack of visual feedback.


Assuntos
Retroalimentação Sensorial/fisiologia , Movimento/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Ombro/fisiologia , Percepção Visual/fisiologia , Adulto , Análise de Variância , Fenômenos Biomecânicos , Feminino , Mãos/fisiologia , Humanos , Masculino , Amplitude de Movimento Articular , Análise e Desempenho de Tarefas , Adulto Jovem
10.
Hum Mov Sci ; 67: 102515, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31499387

RESUMO

A substantial body of research has examined the speed-accuracy tradeoff captured by Fitts' law, demonstrating increases in movement time that occur as aiming tasks are made more difficult by decreasing target width and/or increasing the distance between targets. Yet, serial aiming movements guided by internal spatial representations, rather than by visual views of targets have not been examined in this manner, and the value of confirmatory feedback via different sensory modalities within this paradigm is unknown. Here we examined goal-directed serial aiming movements (tapping back and forth between two targets), wherein targets were visually unavailable during the task. However, confirmatory feedback (auditory, haptic, visual, and bimodal combinations of each) was delivered upon each target acquisition, in a counterbalanced, within-subjects design. Each participant performed the aiming task with their pointer finger, represented within an immersive virtual environment as a 1 cm white sphere, while wearing a head-mounted display. Despite visual target occlusion, movement times increased in accordance with Fitts' law. Though Fitts' law captured performance for each of the sensory feedback conditions, the slopes differed. The effect of increasing difficulty on movement times was least influential in the haptic condition, suggesting more efficient processing of confirmatory haptic feedback during aiming movements guided by internal spatial representations.


Assuntos
Retroalimentação Sensorial/fisiologia , Metas , Desempenho Psicomotor/fisiologia , Feminino , Humanos , Masculino , Motivação , Movimento/fisiologia , Realidade Virtual , Adulto Jovem
11.
Gait Posture ; 74: 114-120, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31499405

RESUMO

PURPOSE: The aim of the study was to evaluate the effect of sensorimotor training on balance measures, and proprioception, among middle-aged and older adults with diabetic peripheral neuropathy (DPN). METHODS: A randomized controlled study with four parallel arms (two intervention groups and two control groups) was conducted at CPRS, Jamia Millia Islamia. Thirty-seven individuals were selected on the basis of inclusion and exclusion criteria. Of these, 16 middle-aged and 21 older adults were randomly allocated to intervention and control groups, respectively. Subjects in the intervention group were administered eight weeks (3days/week) of sensorimotor training, involving 10 different types of exercises, progressed from easy to hard every two weeks, along with diabetes and foot care education; subjects in control group received diabetes and foot care education only. Outcomes measures involved static and dynamic balance measures, centre of pressure (COP) range, COP sway, and proprioception, measured before and after eight weeks. RESULTS: Baseline measures showed significant age effect for timed up and go test (TUG) (p =  0.002), one leg stance (OLS) in eyes open (EO) and eyes closed (EC) (p ≤ 0.041), COP range in front (p =  0.007), back (p =  0.009) and right direction (p =  0.013), COP sway with visual feedback in front-back direction (p =  0.027), COP sway without visual feedback in left-right direction (p =  0.028), and proprioception in right direction (p =  0.026). After intervention, OLS EO and EC on both legs showed significant time effect (p ≤  0.003), group effect as well as time×group interaction (p <  0.05), and age effect and time×age interaction (p ≤  0.04). Functional reach test, TUG, COP range, COP sway, and proprioception were found with significant time effect (p <  0.03), group effect, and time×group interaction (p ≤  0.035). Age effect and time×age interaction were found to be non-significant for all COP ranges and COP sway. CONCLUSION: Sensorimotor training improved static and dynamic balance as well as proprioception measures after eight weeks of exercise intervention. Static balance showed greater improvement in the middle-aged than older aged adults, while dynamic balance and proprioception showed similar results for both.


Assuntos
Neuropatias Diabéticas/fisiopatologia , Terapia por Exercício/métodos , Transtornos Neurológicos da Marcha/fisiopatologia , Modalidades de Fisioterapia , Equilíbrio Postural/fisiologia , Propriocepção/fisiologia , Idoso , Análise de Variância , Retroalimentação Sensorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos de Tempo e Movimento
12.
Gait Posture ; 74: 76-82, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31479852

RESUMO

BACKGROUND: Ankle push-off drives forward progression during gait. Reduced peak ankle moment and peak ankle power may contribute to the increased metabolic cost of walking observed in certain clinical populations. Biofeedback is an effective gait training tool, however biofeedback targeting ankle moment has not been previously studied. RESEARCH QUESTION: Does haptic biofeedback directly targeting ankle moment enable able-bodied adults to modulate peak ankle moment during gait? METHODS: 20 able-bodied adults participated in the study. Participants completed a 90-second baseline walking trial, followed by two 2-minute trials with haptic biofeedback. Haptic biofeedback guided participants to either increase peak ankle moment (Feedback High), or decrease peak ankle moment (Feedback Low). Ten participants received haptic biofeedback alone; the other ten participants additionally received verbal suggestions of movement strategies they could adopt during the biofeedback trials. Two-way analysis of variance was used to determine the effect of walking condition and verbal instruction on key gait parameters. RESULTS: A main effect of walking condition on peak ankle moment and peak ankle power was observed (all P < 0.001). Peak ankle moment did not change from baseline during Feedback High, however peak ankle power was increased (P < 0.001). A decrease in peak ankle moment and peak ankle power was observed during Feedback Low (all P < 0.001). Verbal instruction had a significant interaction effect with walking condition in only a limited number of parameters (all P < 0.05). SIGNIFICANCE: This study demonstrates the effects of haptic biofeedback targeting peak ankle moment during gait. While this study demonstrates that able-bodied individuals have some capacity to modulate their gait pattern in response to direct biofeedback on ankle moment, further investigation is required to develop a biofeedback paradigm that can increase peak ankle moment.


Assuntos
Articulação do Tornozelo/fisiologia , Retroalimentação Sensorial/fisiologia , Marcha/fisiologia , Caminhada/fisiologia , Adulto , Análise de Variância , Feminino , Humanos , Masculino , Adulto Jovem
13.
Gait Posture ; 74: 94-101, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31494385

RESUMO

BACKGROUND: Altered knee motion is one of the most common gait deviations in pediatric populations with gait disorders. The potential for pediatric gait retraining using visual feedback based on knee kinematic patterns is under-explored. RESEARCH QUESTION: This study investigated whether pediatric participants could successfully modify knee flexion patterns in response to a visual kinematic feedback system (VKFS). METHODS: Knee flexion angles from twelve typically developing children and adolescents (6 M, 6 F; 11.9 ±â€¯2.7 years) were calculated using wearable inertial measurement units. Participants were tested while walking on a treadmill using pattern based visual feedback (FB). Four novel target patterns which amplified or attenuated swing phase peak knee flexion were tested. No feedback (NFB) tests assessed the participant's ability to independently reproduce the patterns. Mean absolute cycle error (MACE) and magnitude of peak knee flexion error (PK) were calculated during the last 10 strides of FB and NFB trials. Pre-exposure reference values (R) were also calculated. RESULTS AND SIGNIFICANCE: PK-FB was significantly smaller (p < 0.05) than PK-R for all targets. Average values for PK-NFB were higher than for PK-FB, although PK-NFB remained significantly lower than PK-R for two targets. Contrary to one of the study's hypotheses, MACE-FB and MACE-NFB were larger than MACE-R. The study provided evidence that pediatric participants were able to modify peak knee flexion during gait in the sense targeted by the VKFS. Analysis suggested that MACE increases were explained by increases in gait cycle deviation outside of the changed region.


Assuntos
Retroalimentação Sensorial , Articulação do Joelho/fisiologia , Caminhada/fisiologia , Adolescente , Fenômenos Biomecânicos , Criança , Feminino , Marcha/fisiologia , Humanos , Masculino
14.
PLoS Comput Biol ; 15(9): e1007321, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31479444

RESUMO

We present a new computational model of speech motor control: the Feedback-Aware Control of Tasks in Speech or FACTS model. FACTS employs a hierarchical state feedback control architecture to control simulated vocal tract and produce intelligible speech. The model includes higher-level control of speech tasks and lower-level control of speech articulators. The task controller is modeled as a dynamical system governing the creation of desired constrictions in the vocal tract, after Task Dynamics. Both the task and articulatory controllers rely on an internal estimate of the current state of the vocal tract to generate motor commands. This estimate is derived, based on efference copy of applied controls, from a forward model that predicts both the next vocal tract state as well as expected auditory and somatosensory feedback. A comparison between predicted feedback and actual feedback is then used to update the internal state prediction. FACTS is able to qualitatively replicate many characteristics of the human speech system: the model is robust to noise in both the sensory and motor pathways, is relatively unaffected by a loss of auditory feedback but is more significantly impacted by the loss of somatosensory feedback, and responds appropriately to externally-imposed alterations of auditory and somatosensory feedback. The model also replicates previously hypothesized trade-offs between reliance on auditory and somatosensory feedback and shows for the first time how this relationship may be mediated by acuity in each sensory domain. These results have important implications for our understanding of the speech motor control system in humans.


Assuntos
Modelos Biológicos , Destreza Motora/fisiologia , Fala/fisiologia , Biologia Computacional , Retroalimentação Sensorial/fisiologia , Humanos , Córtex Sensório-Motor/fisiologia
15.
Hum Mov Sci ; 67: 102503, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31376642

RESUMO

Previous research indicates that adding auditory effects to a (silent) action can lead to substantial efficiency gains in the performance of the action, while compromising the connection between the motor and the auditory event (e.g., by removing, or by delaying the auditory effects), leads the agent to compensate for the loss of auditory feedback by executing actions in a way which increases the probability of success or enhances feedback in other modalities, thus departing from the optimal action performance. The current study explored how this motor adaptation was affected when the quality of auditory feedback was reduced by contextual factors, while keeping the physical link between the action and auditory effect intact. In two experiments, participants elicited pure tones by pinching a force sensitive resistor (FSR). In some of the conditions action-effect contingency was reduced by intermixing externally initiated tones with the self-induced ones. Pinch-force measurements indicated that action optimization was affected by contextual factors. The influence of auditory context was the most pronounced when the discrimination of self-induced and external tones was made difficult by the similarity and temporal proximity of the self-induced and external tones. In these conditions, tone eliciting actions were more forceful in comparison to conditions in which no external tones were presented, and in comparison to conditions in which the external tones were easily distinguishable from self-induced ones. This suggests that contextual factors can induce similar motor adjustments as manipulating the physical connection between the action and its sensory consequences.


Assuntos
Adaptação Fisiológica/fisiologia , Percepção Auditiva/fisiologia , Retroalimentação Sensorial/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Feminino , Humanos , Masculino , Destreza Motora/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
16.
Gait Posture ; 73: 215-220, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31376748

RESUMO

BACKGROUND: Postural stability depends on the integration of the multisensory system to produce motor outputs. When visual and somatosensory input is reliable, this reduces reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction. Training one or more of the three sensory systems through vestibular habituation and adaptation can alter sensory weighting and change postural behavior. AIM: The purpose of this study was to assess sensory reweighting of postural control processing after combined vestibular activation with voluntary weight shift training in healthy adults. METHODS: Thirty-three healthy individuals (18-35 y.o.) were randomly assigned to one of three groups: No training (control), visual feedback weight shift training (WST) coupled with an active horizontal headshake (HS) activity to elicit a vestibular perturbation, or the same WST without HS (NoHS). Training was performed 2x/day, every other day (M, W, F), totaling six sessions. Pre- and post- assessments on the Sensory Organization Test (SOT) were performed. Separate between- and within- repeated measures ANOVAs were used to analyze the six SOT equilibrium scores, composite scores, sensory ratios and center of pressure (COP) variables by comparing baseline to post-training. Alpha level was set at p < .05. RESULTS: There was a significant group x session x condition change (p = .012) in the COP multiscale entropy (MSE) velocity sway in the HS group during SOT conditions 5 and 6. Similarly, COP medio-lateral standard deviation sway (ML Std) showed group x session x visual condition (p = .028), due to HS in condition 6 relative to other two groups. CONCLUSION: Postural training can alter sensory organization after a visual feedback-vestibular activation training protocol, suggesting a possible sensory reweighting through vestibular adaptation and/or habituation. SIGNIFICANCE: Translating these findings into a vestibular-impaired population can stimulate the design of a rehabilitation balance protocol.


Assuntos
Modalidades de Fisioterapia , Equilíbrio Postural/fisiologia , Vestíbulo do Labirinto/fisiologia , Adaptação Fisiológica , Adolescente , Adulto , Retroalimentação Sensorial/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
17.
IEEE Int Conf Rehabil Robot ; 2019: 28-33, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374602

RESUMO

Rehabilitation robotics is an emerging field in which gait training has been largely automated allowing more intensive, repetitive motions which are important for facilitating recovery. However, there is no clear evidence that robot-assisted gait training is superior to conventional therapy. A limitation of current approaches to gait therapy is that they do not consider mechanisms of inter-leg coordination and how the sensory feedback from one leg affects the motion of the other leg. Instead they impose motion on the impaired limb. Recent research suggests that utilizing the coupling between limbs in stroke rehabilitation therapies could lead to improved functional outcome. Therefore, a fundamental understanding of underlying sensorimotor mechanisms of inter-leg coordination may facilitate improved interventions in gait therapy. This paper systematically explores and analyzes a sensorimotor mechanism of inter-leg coordination that is stimulated through sudden unilateral low-stiffness perturbations to the walking surface. The potential contribution of each sensory modality to the perception and response of the perturbation will be investigated. Additionally, the neural pathway that relays the sensory signal into the motor output will be described in order to fully characterize this sensorimotor mechanism of inter-leg coordination. This work provides physiological understanding of inter-leg coordination that will benefit robot-assisted gait therapies.


Assuntos
Transtornos Neurológicos da Marcha/reabilitação , Robótica/instrumentação , Reabilitação do Acidente Vascular Cerebral/métodos , Fenômenos Biomecânicos , Retroalimentação Sensorial , Feminino , Transtornos Neurológicos da Marcha/etiologia , Humanos , Masculino , Visão Ocular/fisiologia , Caminhada/fisiologia
18.
IEEE Int Conf Rehabil Robot ; 2019: 121-126, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374617

RESUMO

Proprioception, the ability to sense body position and limb movements in space without visual feedback, is one of the key factors in controlling body movements and performing activities of daily living. However, this capability might be affected after neural injuries such as stroke. Robotic platforms can be used to monitor and promote arm movements and, therefore, can assist in developing rehabilitation protocols that aim to improve proprioception through repetitive reaching motions without vision. The objective of this paper is to investigate if a robotic training protocol improves the end-position reaching proprioceptive sense in three-dimensional (3D) space. As an initial step towards clinical application, a robotic platform was employed to train the end-position proprioceptive sense in six healthy participants. During the training phase, volunteers used their dominant hand to reach without vision to two different targets in 3D space. Positions of these targets were carefully chosen to create a hand movement pattern similar to that used when self-feeding, which is an important activity of daily living. At the end of each training trial, participants were provided with visual feedback to help them move their hands to the exact locations confirmed through haptic feedback. Their performance was evaluated before and after the training in an assessment phase during which participants were asked to move from the start position to the same two targets as well as an additional third one without any visual or haptic feedback. The results from this study show significant improvements in overall reaching accuracy and trajectory smoothness, demonstrated by 41% decrease in the average end-position error and 13% reduction in the average index of curvature after the training. This research suggests the potential of designing robotic rehabilitation protocols for improving 3D proprioception.


Assuntos
Braço/fisiologia , Modalidades de Fisioterapia/instrumentação , Propriocepção/fisiologia , Robótica/instrumentação , Atividades Cotidianas , Adulto , Desenho de Equipamento , Retroalimentação , Retroalimentação Sensorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Postura , Adulto Jovem
19.
IEEE Int Conf Rehabil Robot ; 2019: 1019-1024, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374763

RESUMO

Innovative research in the fields of prosthetic, neurorehabilitation, motor control and human physiology has been focusing on the study of proprioception, the sense through which we perceive the position and movement of our body, and great achievements have been obtained regarding its assessment and characterization. However, how proprioceptive signals are combined with other sensory modalities and processed by the central nervous system to form a conscious body image, is still unknown. Such a crucial question was addressed in this study, which involved 23 healthy subjects, by combining a robot-based proprioceptive test with a specific analysis of electroencephalographic activity (EEG) in the $\mu$ frequency band (8-12 Hz). We observed important activation in the motor area contralateral to the moving hand, and besides, a substantial bias in brain activation and proprioceptive acuity when visual feedback was provided in addition to the proprioceptive information during movement execution. In details, brain activation and proprioceptive acuity were both higher in case of movements performed with visual feedback. Remarkably, we also found a correlation between the level of activation in the brain motor area contralateral to the moving hand and the value of proprioceptive acuity.


Assuntos
Eletroencefalografia/métodos , Propriocepção/fisiologia , Robótica , Adolescente , Adulto , Encéfalo/fisiologia , Retroalimentação Sensorial/fisiologia , Feminino , Humanos , Masculino , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Adulto Jovem
20.
IEEE Int Conf Rehabil Robot ; 2019: 1127-1132, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374781

RESUMO

The use of robotic devices to provide active motor support and sensory feedback of ongoing motor intention, by means of a Brain Computer Interface (BCI), has received growing support by recent literature, with particular focus on neurorehabilitation therapies. At the same time, performance in the use of the BCI has become a more critical factor, since it directly influences congruency and consistency of the provided sensory feedback. As motor imagery is the mental simulation of a given movement without depending on residual function, training of patients in the use of motor imagery BCI can be extended beyond each rehabilitation session, and practiced by using simpler devices than rehabilitation robots available in the hospital. In this work, we investigated the use of haptic stimulation provided by vibrating electromagnetic motors to enhance BCI system training. The BCI is based on motor imagery of hand grasping and designed to operate a hand exoskeleton. We investigated whether haptic stimulation at fingerpads proves to be more effective than stimulation at wrist, already experimented in literature, due to the higher density of mechano-receptors. Our results did not show significant differences between the two body locations in BCI performance, yet a wider and more stable event-relateddesynchronization appeared for the finger-located stimulation. Future investigations will put in relation training with haptic feedback at fingerpads with BCI performance using the handexoskeleton, in grasping tasks that naturally involve haptic feedback at fingerpads.


Assuntos
Exoesqueleto Energizado , Mãos/fisiologia , Interfaces Cérebro-Computador , Retroalimentação Sensorial/fisiologia , Força da Mão/fisiologia , Humanos , Punho/fisiologia
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