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Zill SN, Dallmann CJ, Zyhowski W, Chaudhry H, Gebehart C, Szczecinski NS. Mechanosensory encoding of forces in walking uphill and downhill: force feedback can stabilize leg movements in stick insects. J Neurophysiol 2024; 131:198-215. [PMID: 38166479 DOI: 10.1152/jn.00414.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 12/28/2023] [Accepted: 12/29/2023] [Indexed: 01/04/2024] Open
Abstract
Force feedback could be valuable in adapting walking to diverse terrains, but the effects of changes in substrate inclination on discharges of sensory receptors that encode forces have rarely been examined. In insects, force feedback is provided by campaniform sensilla, mechanoreceptors that monitor forces as cuticular strains. We neurographically recorded responses of stick insect tibial campaniform sensilla to "naturalistic" forces (joint torques) that occur at the hind leg femur-tibia (FT) joint in uphill, downhill, and level walking. The FT joint torques, obtained in a previous study that used inverse dynamics to analyze data from freely moving stick insects, are quite variable during level walking (including changes in sign) but are larger in magnitude and more consistent when traversing sloped surfaces. Similar to vertebrates, insects used predominantly extension torque in propulsion on uphill slopes and flexion torques to brake forward motion when going downhill. Sensory discharges to joint torques reflected the torque direction but, unexpectedly, often occurred as multiple bursts that encoded the rate of change of positive forces (dF/dt) even when force levels were high. All discharges also showed hysteresis (history dependence), as firing substantially decreased or ceased during transient force decrements. These findings have been tested in simulation in a mathematical model of the sensilla (Szczecinski NS, Dallmann CJ, Quinn RD, Zill SN. Bioinspir Biomim 16: 065001, 2021) that accurately reproduced the biological data. Our results suggest the hypothesis that sensory feedback from the femoro-tibial joint indicating force dynamics (dF/dt) can be used to counter the instability in traversing sloped surfaces in animals and, potentially, in walking machines.NEW & NOTEWORTHY Discharges of sensory receptors (campaniform sensilla) in the hind legs of stick insects can differentially signal forces that occur in walking uphill versus walking downhill. Unexpectedly, sensory firing most closely reflects the rate of change of force (dF/dt) even when the force levels are high. These signals have been replicated in a mathematical model of the receptors and could be used to stabilize leg movements both in the animal and in a walking robot.
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Affiliation(s)
- Sasha N Zill
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, United States
| | - Chris J Dallmann
- Department of Neurobiology and Genetics, Julius-Maximilians-Universität-Würzburg, Würzburg, Germany
| | - William Zyhowski
- Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia, United States
| | - Hibba Chaudhry
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, United States
| | - Corinna Gebehart
- Champalimaud Foundation, Champalimaud Research, Lisbon, Portugal
- Department of Animal Physiology, Institute of Zoology, Biocenter Cologne, University of Cologne, Cologne, Germany
| | - Nicholas S Szczecinski
- Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia, United States
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Becerra-Yañez P, Núñez-Cortés R, López R, Ortiz M, Pérez M, Cruz-Montecinos C. Treadmill exercise post dry needling improves heel rise in patients recovering from surgical ankle fracture: A randomised controlled trial. J Bodyw Mov Ther 2023; 34:60-65. [PMID: 37301559 DOI: 10.1016/j.jbmt.2023.04.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 01/10/2023] [Accepted: 04/12/2023] [Indexed: 06/12/2023]
Abstract
INTRODUCTION Little is known about the effectiveness of the dry needling technique (DNT) plus exercise on motor function in musculoskeletal diseases. OBJECTIVE To evaluate the effects of treadmill exercise immediately after DNT on pain, range of motion (ROM) and bilateral heel rise test in patients recovering from surgical ankle fracture. METHOD A randomised, parallel-group, controlled trial was conducted on patients recovering from surgical ankle fracture. Patients received the DNT intervention for the triceps surae muscle. Then, participants were randomly assigned to the experimental (DNT plus incline treadmill for 20 min) or control group (DNT plus rest for 20 min). Baseline and immediate post-intervention assessments included: visual analogue scale (VAS), maximal ankle dorsiflexion ROM and bilateral heel rise test. RESULTS A total of 20 patients recovering from surgical ankle fracture were included. Eleven patients were assigned to the experimental group (mean age 46 ± 12.6 years, 2/9 men/women) and nine to the control group (mean age 52 ± 13.4 years, 2/7 men/women). Two-way ANOVA showed a significant time × group interaction for bilateral heel rise test (F = 5.514, p = 0.030, ηp2 = 0.235). Both groups increased the number of repetitions (p < 0.001), however, the experimental group showed a significant difference compared to control group (mean difference: 2.73 repetitions; p = 0.030). There was no time × group interaction in VAS and ROM (p > 0.05). CONCLUSION Our results indicate that treadmill exercise after dry needling improves plantar flexors motor function more than rest after dry needling in patients with surgical ankle fracture.
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Affiliation(s)
- Pablo Becerra-Yañez
- Division of Research, Devolvement and Innovation in Kinesiology, Kinesiology Unit, San José Hospital, Santiago, Chile
| | - Rodrigo Núñez-Cortés
- Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Ricardo López
- Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Morín Ortiz
- Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Martín Pérez
- Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Carlos Cruz-Montecinos
- Division of Research, Devolvement and Innovation in Kinesiology, Kinesiology Unit, San José Hospital, Santiago, Chile; Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile.
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Horn JC, Gregg RD. Nonholonomic Virtual Constraints for Control of Powered Prostheses Across Walking Speeds. IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY : A PUBLICATION OF THE IEEE CONTROL SYSTEMS SOCIETY 2022; 30:2062-2071. [PMID: 35990403 PMCID: PMC9390073 DOI: 10.1109/tcst.2021.3133823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This paper presents a method to design a nonholonomic virtual constraint (NHVC) controller that produces multiple distinct stance-phase trajectories for corresponding walking speeds. NHVCs encode velocity-dependent joint trajectories via momenta conjugate to the unactuated degree(s)-of-freedom of the system. We recently introduced a method for designing NHVCs that allow for stable bipedal robotic walking across variable terrain slopes. This work extends the notion of NHVCs for application to variable-cadence powered prostheses. Using the segmental conjugate momentum for the prosthesis, an optimization problem is used to design a single stance-phase NHVC for three distinct walking speed trajectories (slow, normal, and fast). This stance-phase controller is implemented with a holonomic swing phase controller on a powered knee-ankle prosthesis, and experiments are conducted with an able-bodied user walking in steady and non-steady velocity conditions. The control scheme is capable of representing 1) multiple, task-dependent reference trajectories, and 2) walking gait variance due to both temporal and kinematic changes in user motion.
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Affiliation(s)
- Jonathan C Horn
- Department of Mechanical Engineering and Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Robert D Gregg
- Department of Electrical Engineering and Computer Science and the Robotics Institute, University of Michigan, Ann Arbor, MI 48109 USA
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Rasul A, Lorentzen J, Frisk RF, Sinkjær T, Nielsen JB. Contribution of sensory feedback to Soleus muscle activity during voluntary contraction in humans. J Neurophysiol 2022; 127:1147-1158. [PMID: 35320034 DOI: 10.1152/jn.00430.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sensory feedback contributes to plantar flexor muscle activity during walking, but it is unknown whether this is also the case during non-locomotor movements. Here, we explored the effect of reduction of sensory feedback to ankle plantar flexors during voluntary isometric contractions. 13 adult volunteers were seated with the right leg attached to a foot plate which could be moved in dorsi- or plantarflexion direction by a computer-controlled motor. During static plantar flexion while the plantar flexors were slowly stretched, a sudden plantar flexion caused a decline in Soleus EMG at stretch reflex latency. This decline in EMG remained when transmission from dorsiflexors was blocked. It disappeared following block of transmission from plantar flexors. Imposed plantarflexion failed to produce a similar decline in EMG during static or ramp-and-hold plantar flexion in the absence of slow stretch. Instead, a decline in EMG was observed 15-20 ms later, which disappeared following block of transmission from dorsiflexors. Imposed plantarflexion in the stance phase during walking caused a decline in SOL EMG which in contrast remained following block of transmission from dorsiflexors. These findings imply that the contribution of spinal interneurons to the neural drive to muscles during gait and voluntary movement differs and supports that a locomotion specific spinal network contributes to plantar flexor muscle activity during human walking.
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Affiliation(s)
- Aqella Rasul
- Department of Neuroscience, Univ. of Copenhagen, Copenhagen, Denmark
| | - Jakob Lorentzen
- Department of Neuroscience, Univ. of Copenhagen, Copenhagen, Denmark
| | - Rasmus Feld Frisk
- Department of Neuroscience, Univ. of Copenhagen, Copenhagen, Denmark
| | - Thomas Sinkjær
- Department of Health Science and Technology. Aalborg University, Denmark
| | - Jens Bo Nielsen
- Department of Neuroscience, Univ. of Copenhagen, Copenhagen, Denmark.,Elsass Foundation, Charlottenlund, Denmark
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Abstract
When animals walk overground, mechanical stimuli activate various receptors located in muscles, joints, and skin. Afferents from these mechanoreceptors project to neuronal networks controlling locomotion in the spinal cord and brain. The dynamic interactions between the control systems at different levels of the neuraxis ensure that locomotion adjusts to its environment and meets task demands. In this article, we describe and discuss the essential contribution of somatosensory feedback to locomotion. We start with a discussion of how biomechanical properties of the body affect somatosensory feedback. We follow with the different types of mechanoreceptors and somatosensory afferents and their activity during locomotion. We then describe central projections to locomotor networks and the modulation of somatosensory feedback during locomotion and its mechanisms. We then discuss experimental approaches and animal models used to investigate the control of locomotion by somatosensory feedback before providing an overview of the different functional roles of somatosensory feedback for locomotion. Lastly, we briefly describe the role of somatosensory feedback in the recovery of locomotion after neurological injury. We highlight the fact that somatosensory feedback is an essential component of a highly integrated system for locomotor control. © 2021 American Physiological Society. Compr Physiol 11:1-71, 2021.
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Affiliation(s)
- Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Quebec, Canada
| | - Turgay Akay
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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Negotiating ground level perturbations in walking: Visual perception and expectation of curb height modulate muscle activity. J Biomech 2020; 113:110121. [PMID: 33186886 DOI: 10.1016/j.jbiomech.2020.110121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/22/2020] [Accepted: 10/29/2020] [Indexed: 11/20/2022]
Abstract
To negotiate visible and unpredictable changes in ground level, humans use different control strategies depending on the visibility. In case of fully visible perturbations, humans can anticipate the occurrence and the magnitude of the perturbation. In case of a camouflaged perturbation, they can anticipate the occurrence based on the camouflage cover but need to predict the magnitude from experience, as it is not visible. The purpose of this study was to investigate the anticipatory muscular control strategy humans employ when walking down curbs of different height and to investigate how this strategy differs if the step down is fully visible or camouflaged. The activity of five bilateral lower limb muscles (M. gastrocnemius medialis, M. soleus, M. tibialis anterior, M. biceps femoris and M. vastus medialis) of eight healthy subjects was recorded during walking down visible (0, -10 and -20 cm) and camouflaged curbs (0 and -10 cm). The results reveal that the M. gastrocnemius shows a clear anticipatory adaptation to visible curbs in the contralateral and partly also the ipsilateral leg, which further depends on the curb height. Furthermore, in case of a camouflaged perturbation, M. gastrocnemius activity of the contralateral leg shows an adaptation that indicates an average prediction of the curb height, presumably based on previous experience.
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Bertrand-Charette M, Dambreville C, Bouyer LJ, Roy JS. Systematic review of motor control and somatosensation assessment tests for the ankle. BMJ Open Sport Exerc Med 2020; 6:e000685. [PMID: 32655878 PMCID: PMC7342858 DOI: 10.1136/bmjsem-2019-000685] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2020] [Indexed: 12/26/2022] Open
Abstract
Background/Aim Ankle sprains are frequent musculoskeletal injuries that can lead to sensorimotor deficits provoking long-term instability at the ankle joint. A broad variety of clinical tests currently exist to assess sensorimotor processing, and are commonly clinically referred to as proprioceptive tests. However, there is a discrepancy in the use of the term proprioception when looking at the main outcome of these tests. As identifying specific deficits is important for motor recovery, it is critical for clinicians to select the most appropriate tests. Methods A systematic review of four databases was performed to provide an up-to-date review of the psychometric properties of available tests referred to as proprioceptive tests. Seventy-nine articles on eight ankle proprioceptive tests were included and critically appraised. Data on validity, reliability and responsiveness were extracted from the included articles and synthesised. The tests reviewed were then divided into two categories based on their main outcome: motor control or somatosensation. Results Strong evidence showed that the Star Excursion Balance Test, a motor control test, is capable of differentiating between stable and unstable ankles. Moderate evidence suggests that somatosensation tests, such as Joint Position Sense, are also valid and reliable, but their responsiveness has yet to be evaluated. Conclusions Together, these findings indicate that the Star Excursion Balance Test can be used in the clinic to assess motor control based on its excellent psychometric properties. However, as ankle stability control involves complex sensorimotor interactions, care has to be taken regarding the use of this test as a specific tool for proprioception assessment.
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Affiliation(s)
- Michaël Bertrand-Charette
- Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Center for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec City, Quebec, Canada
| | - Charline Dambreville
- Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Center for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec City, Quebec, Canada
| | - Laurent J Bouyer
- Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Center for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec City, Quebec, Canada
| | - Jean-Sébastien Roy
- Department of Rehabilitation, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Center for Interdisciplinary Research in Rehabilitation and Social Integration, Quebec City, Quebec, Canada
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Nanivadekar AC, Ayers CA, Gaunt RA, Weber DJ, Fisher LE. Selectivity of afferent microstimulation at the DRG using epineural and penetrating electrode arrays. J Neural Eng 2019; 17:016011. [PMID: 31577993 PMCID: PMC9131467 DOI: 10.1088/1741-2552/ab4a24] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE We have shown previously that microstimulation of the lumbar dorsal root ganglia (L5-L7 DRG) using penetrating microelectrodes, selectively recruits distal branches of the sciatic and femoral nerves in an acute preparation. However, a variety of challenges limit the clinical translatability of DRG microstimulation via penetrating electrodes. For clinical translation of a DRG somatosensory neural interface, electrodes placed on the epineural surface of the DRG may be a viable path forward. The goal of this study was to evaluate the recruitment properties of epineural electrodes and compare their performance with that of penetrating electrodes. Here, we compare the number of selectively recruited distal nerve branches and the threshold stimulus intensities between penetrating and epineural electrode arrays. APPROACH Antidromically propagating action potentials were recorded from multiple distal branches of the femoral and sciatic nerves in response to epineural stimulation on 11 ganglia in four cats to quantify the selectivity of DRG stimulation. Compound action potentials (CAPs) were recorded using nerve cuff electrodes implanted around up to nine distal branches of the femoral and sciatic nerve trunks. We also tested stimulation selectivity with penetrating microelectrode arrays implanted into ten ganglia in four cats. A binary search was carried out to identify the minimum stimulus intensity that evoked a response at any of the distal cuffs, as well as whether the threshold response selectively occurred in only a single distal nerve branch. MAIN RESULTS Stimulation evoked activity in just a single peripheral nerve through 67% of epineural electrodes (35/52) and through 79% of the penetrating microelectrodes (240/308). The recruitment threshold (median = 9.67 nC/phase) and dynamic range of epineural stimulation (median = 1.01 nC/phase) were significantly higher than penetrating stimulation (0.90 nC/phase and 0.36 nC/phase, respectively). However, the pattern of peripheral nerves recruited for each DRG were similar for stimulation through epineural and penetrating electrodes. SIGNIFICANCE Despite higher recruitment thresholds, epineural stimulation provides comparable selectivity and superior dynamic range to penetrating electrodes. These results suggest that it may be possible to achieve a highly selective neural interface with the DRG without penetrating the epineurium.
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Affiliation(s)
- Ameya C Nanivadekar
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, United States of America. Rehabilitation Neural Engineering Laboratories, 3520 Fifth Avenue, Suite 300, Pittsburgh, PA 15213, United States of America. Center for Neural Basis of Cognition, Pittsburgh, PA 15213, United States of America
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Naidu A, Graham SA, Brown DA. Fore-aft resistance applied at the center of mass using a novel robotic interface proportionately increases propulsive force generation in healthy nonimpaired individuals walking at a constant speed. J Neuroeng Rehabil 2019; 16:111. [PMID: 31492156 PMCID: PMC6731616 DOI: 10.1186/s12984-019-0577-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/19/2019] [Indexed: 12/24/2022] Open
Abstract
Background Past studies have utilized external interfaces like resistive bands and motor-generated pulling systems to increase limb propulsion during walking on a motorized treadmill. However, assessing changes in limb propulsion against increasing resistance demands during self-controlled walking has not been undertaken. Purpose We assessed limb propulsion against increasing fore-aft loading demands by applying graded fore-aft (FA) resistance at the center of mass during walking in a novel, intent-driven treadmill environment that allowed participants to control their walking speeds. We hypothesized that to maintain a target speed against progressively increasing resistance, participants would proportionately increase their limb propulsion without increasing vertical force production, with accompanying increases in trailing limb angle and positive joint work. Methods Seventeen healthy-nonimpaired participants (mean age 52 yrs., SD = 11) walked at a target, self-controlled speed of 1.0 m/s against 10, 15, 20, and 25% (% body weight) FA resistance levels. We primarily assessed linear slope values across FA resistance levels for mean propulsive force and impulse and vertical impulse of the dominant limb using one-sample t-tests. We further assessed changes in trailing and leading limb angles and joint work using one-way ANOVAs. Results Participants maintained their target velocity within an a priori defined acceptable range of 1.0 m/s ± 0.2. They significantly increased propulsion proportional to FA resistance (propulsive force mean slope = 2.45, SD = 0.7, t (16) =14.44, p < 0.01; and propulsive impulse mean slope = 0.7, SD = 0.25, t (16) = 11.84, p < 0.01), but had no changes in vertical impulse (mean slope = − 0.04, SD =0.17, p > 0.05) across FA resistance levels. Mean trailing limb angle increased from 24.3° at 10% resistance to 27.4° at 25% (p < 0.05); leading limb angle decreased from − 18.4° to − 12.6° (p < 0.05). We also observed increases in total positive limb work (F (1.7, 26) = 16.88, p ≤ 0.001, η2 = 0.5), primarily attributed to the hip and ankle joints. Conclusions FA resistance applied during self-driven walking resulted in increased propulsive-force output of healthy-nonimpaired individuals with accompanying biomechanical changes that facilitated greater limb propulsion. Future rehabilitation interventions for neurological populations may be able to utilize this principle to design task-specific interventions like progressive strength training and workload manipulation during aerobic training for improving walking function. Electronic supplementary material The online version of this article (10.1186/s12984-019-0577-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Avantika Naidu
- Program in Rehabilitation Sciences, Departments of Physical & Occupational Therapy, School of Health Professions, University of Alabama at Birmingham, 1716 9th Avenue South, Birmingham, AL, 35233, USA. .,Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, 300 First Avenue, Boston, MA, 02129, 1575 Cambridge St, Cambridge, MA, 02138, USA.
| | - Sarah A Graham
- University of California San Diego, School of Health Sciences, 9500 Gilman Drive, La Jolla, CA, 92093-0012, USA
| | - David A Brown
- The University of Texas Medical Branch, School of Health Professions, 301 University Blvd, Galveston, TX, 77555-0128, USA
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Steuer I, Guertin PA. Central pattern generators in the brainstem and spinal cord: an overview of basic principles, similarities and differences. Rev Neurosci 2019; 30:107-164. [PMID: 30543520 DOI: 10.1515/revneuro-2017-0102] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/30/2018] [Indexed: 12/11/2022]
Abstract
Central pattern generators (CPGs) are generally defined as networks of neurons capable of enabling the production of central commands, specifically controlling stereotyped, rhythmic motor behaviors. Several CPGs localized in brainstem and spinal cord areas have been shown to underlie the expression of complex behaviors such as deglutition, mastication, respiration, defecation, micturition, ejaculation, and locomotion. Their pivotal roles have clearly been demonstrated although their organization and cellular properties remain incompletely characterized. In recent years, insightful findings about CPGs have been made mainly because (1) several complementary animal models were developed; (2) these models enabled a wide variety of techniques to be used and, hence, a plethora of characteristics to be discovered; and (3) organizations, functions, and cell properties across all models and species studied thus far were generally found to be well-preserved phylogenetically. This article aims at providing an overview for non-experts of the most important findings made on CPGs in in vivo animal models, in vitro preparations from invertebrate and vertebrate species as well as in primates. Data about CPG functions, adaptation, organization, and cellular properties will be summarized with a special attention paid to the network for locomotion given its advanced level of characterization compared with some of the other CPGs. Similarities and differences between these networks will also be highlighted.
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Affiliation(s)
- Inge Steuer
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
| | - Pierre A Guertin
- Neuroscience Unit, Laval University Medical Center (CHUL - CHU de Québec), 2705 Laurier Blvd, Quebec City, Quebec G1V 4G2, Canada
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Laval University, Quebec City, Quebec G1V 0A6, Canada
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Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury. Exp Brain Res 2019; 237:2461-2479. [PMID: 31309252 PMCID: PMC6751142 DOI: 10.1007/s00221-019-05603-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/08/2019] [Indexed: 12/28/2022]
Abstract
In people with spasticity due to chronic incomplete spinal cord injury (SCI), it has been presumed that the abnormal stretch reflex activity impairs gait. However, locomotor stretch reflexes across all phases of walking have not been investigated in people with SCI. Thus, to understand modulation of stretch reflex excitability during spastic gait, we investigated soleus stretch reflexes across the entire gait cycle in nine neurologically normal participants and nine participants with spasticity due to chronic incomplete SCI (2.5–11 year post-injury). While the participant walked on the treadmill at his/her preferred speed, unexpected ankle dorsiflexion perturbations (6° at 250°/s) were imposed every 4–6 steps. The soleus H-reflex was also examined. In participants without SCI, spinal short-latency “M1”, spinal medium latency “M2”, and long-latency “M3” were clearly modulated throughout the step cycle; the responses were largest in the mid-stance and almost completely suppressed during the stance-swing transition and swing phases. In participants with SCI, M1 and M2 were abnormally large in the mid–late-swing phase, while M3 modulation was similar to that in participants without SCI. The H-reflex was also large in the mid–late-swing phase. Elicitation of H-reflex and stretch reflexes in the late swing often triggered clonus and affected the soleus activity in the following stance. In individuals without SCI, moderate positive correlation was found between H-reflex and stretch reflex sizes across the step cycle, whereas in participants with SCI, such correlation was weak to non-existing, suggesting that H-reflex investigation would not substitute for stretch reflex investigation in individuals after SCI.
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12
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Brain Activation During Passive and Volitional Pedaling After Stroke. Motor Control 2019; 23:52-80. [PMID: 30012052 PMCID: PMC6685765 DOI: 10.1123/mc.2017-0059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 01/06/2018] [Accepted: 02/25/2018] [Indexed: 11/18/2022]
Abstract
Background: Prior work indicates that pedaling-related brain activation is lower in people with stroke than in controls. We asked whether this observation could be explained by between-group differences in volitional motor commands and pedaling performance. Methods: Individuals with and without stroke performed passive and volitional pedaling while brain activation was recorded with functional magnetic resonance imaging. The passive condition eliminated motor commands to pedal and minimized between-group differences in pedaling performance. Volume, intensity, and laterality of brain activation were compared across conditions and groups. Results: There were no significant effects of condition and no Group × Condition interactions for any measure of brain activation. Only 53% of subjects could minimize muscle activity for passive pedaling. Conclusions: Altered motor commands and pedaling performance are unlikely to account for reduced pedaling-related brain activation poststroke. Instead, this phenomenon may be due to functional or structural brain changes. Passive pedaling can be difficult to achieve and may require inhibition of excitatory descending drive.
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Haeufle DFB, Schmortte B, Geyer H, Müller R, Schmitt S. The Benefit of Combining Neuronal Feedback and Feed-Forward Control for Robustness in Step Down Perturbations of Simulated Human Walking Depends on the Muscle Function. Front Comput Neurosci 2018; 12:80. [PMID: 30356859 PMCID: PMC6190627 DOI: 10.3389/fncom.2018.00080] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 09/10/2018] [Indexed: 11/28/2022] Open
Abstract
It is often assumed that the spinal control of human locomotion combines feed-forward central pattern generation with sensory feedback via muscle reflexes. However, the actual contribution of each component to the generation and stabilization of gait is not well understood, as direct experimental evidence for either is difficult to obtain. We here investigate the relative contribution of the two components to gait stability in a simulation model of human walking. Specifically, we hypothesize that a simple linear combination of feedback and feed-forward control at the level of the spinal cord improves the reaction to unexpected step down perturbations. In previous work, we found preliminary evidence supporting this hypothesis when studying a very reduced model of rebounding behaviors. In the present work, we investigate if the evidence extends to a more realistic model of human walking. We revisit a model that has previously been published and relies on spinal feedback control to generate walking. We extend the control of this model with a feed-forward muscle activation pattern. The feed-forward pattern is recorded from the unperturbed feedback control output. We find that the improvement in the robustness of the walking model with respect to step down perturbations depends on the ratio between the two strategies and on the muscle to which they are applied. The results suggest that combining feed-forward and feedback control is not guaranteed to improve locomotion, as the beneficial effects are dependent on the muscle and its function during walking.
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Affiliation(s)
- Daniel F B Haeufle
- Multi-Level Modeling in Motor Control and Rehabilitation Robotics, Hertie Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls Universität Tübingen, Tübingen, Germany
| | - Birgit Schmortte
- Biomechanics and Biorobotics, Stuttgart Center for Simulation Sciences (SC SimTech), University of Stuttgart, Stuttgart, Germany
| | - Hartmut Geyer
- Robotics Institute, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Roy Müller
- Institute of Sport Science, Friedrich Schiller University of Jena, Jena, Germany.,Department of Neurology and Department of Orthopedic Surgery, Klinikum Bayreuth GmbH, Bayreuth, Germany
| | - Syn Schmitt
- Biomechanics and Biorobotics, Stuttgart Center for Simulation Sciences (SC SimTech), University of Stuttgart, Stuttgart, Germany
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14
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Lower extremity joint-level responses to pelvis perturbation during human walking. Sci Rep 2018; 8:14621. [PMID: 30279499 PMCID: PMC6168500 DOI: 10.1038/s41598-018-32839-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 09/11/2018] [Indexed: 11/15/2022] Open
Abstract
The human leg joints play a major role in balance control during walking. They facilitate leg swing, and modulate the ground (re)action forces to prevent a fall. The aim of this study is to provide and explore data on perturbed human walking to gain a better understanding of balance recovery during walking through joint-level control. Healthy walking subjects randomly received anteroposterior and mediolateral pelvis perturbations at the instance of toe-off. The open-source modeling tool OpenSim was used to perform inverse kinematics and inverse dynamics analysis. We found hip joint involvement in accelerating and then halting leg swing, suggesting active preparation for foot placement. Additionally, responses in the stance leg’s ankle and hip joints contribute to balance recovery by decreasing the body’s velocity in the perturbation direction. Modulation also occurs in the plane perpendicular to the perturbation direction, to safeguard balance in both planes. Finally, the recorded muscle activity suggests both spinal and supra-spinal mediated contributions to balance recovery, scaling with perturbation magnitude and direction. The presented data provide a unique and multi-joint insight in the complexity of both frontal and sagittal plane balance control during human walking in terms of joint angles, moments, and power, as well as muscle EMG responses.
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15
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Mayer WP, Murray AJ, Brenner-Morton S, Jessell TM, Tourtellotte WG, Akay T. Role of muscle spindle feedback in regulating muscle activity strength during walking at different speed in mice. J Neurophysiol 2018; 120:2484-2497. [PMID: 30133381 DOI: 10.1152/jn.00250.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Terrestrial animals increase their walking speed by increasing the activity of the extensor muscles. However, the mechanism underlying how this speed-dependent amplitude modulation is achieved remains obscure. Previous studies have shown that group Ib afferent feedback from Golgi tendon organs that signal force is one of the major regulators of the strength of muscle activity during walking in cats and humans. In contrast, the contribution of group Ia/II afferent feedback from muscle spindle stretch receptors that signal angular displacement of leg joints is unclear. Some studies indicate that group II afferent feedback may be important for amplitude regulation in humans, but the role of muscle spindle feedback in regulation of muscle activity strength in quadrupedal animals is very poorly understood. To examine the role of feedback from muscle spindles, we combined in vivo electrophysiology and motion analysis with mouse genetics and gene delivery with adeno-associated virus. We provide evidence that proprioceptive sensory feedback from muscle spindles is important for the regulation of the muscle activity strength and speed-dependent amplitude modulation. Furthermore, our data suggest that feedback from the muscle spindles of the ankle extensor muscles, the triceps surae, is the main source for this mechanism. In contrast, muscle spindle feedback from the knee extensor muscles, the quadriceps femoris, has no influence on speed-dependent amplitude modulation. We provide evidence that proprioceptive feedback from ankle extensor muscles is critical for regulating muscle activity strength as gait speed increases. NEW & NOTEWORTHY Animals upregulate the activity of extensor muscles to increase their walking speed, but the mechanism behind this is not known. We show that this speed-dependent amplitude modulation requires proprioceptive sensory feedback from muscle spindles of ankle extensor muscle. In the absence of muscle spindle feedback, animals cannot walk at higher speeds as they can when muscle spindle feedback is present.
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Affiliation(s)
- William P Mayer
- Atlantic Mobility Action Project, Brain Repair Center, Department of Medical Neuroscience, Dalhousie University , Halifax, Nova Scotia , Canada.,Department of Morphology, Federal University of Espirito Santo , Vitoria , Brazil
| | - Andrew J Murray
- Sainsbury Wellcome Center for Neural Circuits and Behaviour, University College London , London , United Kingdom
| | - Susan Brenner-Morton
- Howard Hughes Medical Institute, Department of Neuroscience, Columbia University , New York, New York
| | - Thomas M Jessell
- Howard Hughes Medical Institute, Department of Neuroscience, Columbia University , New York, New York
| | - Warren G Tourtellotte
- Department of Pathology and Laboratory Medicine, Cedar Sinai Medical Center, West Hollywood, California
| | - Turgay Akay
- Atlantic Mobility Action Project, Brain Repair Center, Department of Medical Neuroscience, Dalhousie University , Halifax, Nova Scotia , Canada
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16
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Zill SN, Dallmann CJ, Büschges A, Chaudhry S, Schmitz J. Force dynamics and synergist muscle activation in stick insects: the effects of using joint torques as mechanical stimuli. J Neurophysiol 2018; 120:1807-1823. [PMID: 30020837 DOI: 10.1152/jn.00371.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Many sensory systems are tuned to specific parameters of behaviors and have effects that are task-specific. We have studied how force feedback contributes to activation of synergist muscles in serially homologous legs of stick insects. Forces were applied using conventional half-sine or ramp and hold functions. We also utilized waveforms of joint torques calculated from experiments in freely walking animals. In all legs, forces applied to either the tarsus (foot) or proximal leg segment (trochanter) activated synergist muscles that generate substrate grip and support, but coupling of the depressor muscle to tarsal forces was weak in the front legs. Activation of trochanteral receptors using ramp and hold functions generated positive feedback to the depressor muscle in all legs when animals were induced to seek substrate grip. However, discharges of the synergist flexor muscle showed adaptation at moderate force levels. In contrast, application of forces using torque waveforms, which do not have a static hold phase, produced sustained discharges in muscle synergies with little adaptation. Firing frequencies reflected the magnitude of ground reaction forces, were graded to changes in force amplitude, and could also be modulated by transient force perturbations added to the waveforms. Comparison of synergist activation by torques and ramp and hold functions revealed a strong influence of force dynamics (dF/d t). These studies support the idea that force receptors can act to tune muscle synergies synchronously to the range of force magnitudes and dynamics that occur in each leg according to their specific use in behavior. NEW & NOTEWORTHY The effects of force receptors (campaniform sensilla) on leg muscles and synergies were characterized in stick insects using both ramp and hold functions and waveforms of joint torques calculated by inverse dynamics. Motor responses were sustained and showed reduced adaptation to the more "natural" and nonlinear torque stimuli. Calculation of the first derivative (dF/d t) of the torque waveforms demonstrated that this difference was correlated with the dynamic sensitivities of the system.
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Affiliation(s)
- Sasha N Zill
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Chris J Dallmann
- Department of Biological Cybernetics, Bielefeld University , Bielefeld , Germany
| | - Ansgar Büschges
- Department of Animal Physiology, Institute of Zoology, Biocenter, University of Cologne , Cologne , Germany
| | - Sumaiya Chaudhry
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
| | - Josef Schmitz
- Department of Biological Cybernetics, Bielefeld University , Bielefeld , Germany
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17
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Quintero D, Villarreal DJ, Lambert DJ, Kapp S, Gregg RD. Continuous-Phase Control of a Powered Knee-Ankle Prosthesis: Amputee Experiments Across Speeds and Inclines. IEEE T ROBOT 2018; 34:686-701. [PMID: 30008623 PMCID: PMC6042879 DOI: 10.1109/tro.2018.2794536] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Control systems for powered prosthetic legs typically divide the gait cycle into several periods with distinct controllers, resulting in dozens of control parameters that must be tuned across users and activities. To address this challenge, this paper presents a control approach that unifies the gait cycle of a powered knee-ankle prosthesis using a continuous, user-synchronized sense of phase. Virtual constraints characterize the desired periodic joint trajectories as functions of a phase variable across the entire stride. The phase variable is computed from residual thigh motion, giving the amputee control over the timing of the prosthetic joint patterns. This continuous sense of phase enabled three transfemoral amputee subjects to walk at speeds from 0.67 to 1.21 m/s and slopes from -2.5 to +9.0 deg. Virtual constraints based on task-specific kinematics facilitated normative adjustments in joint work across walking speeds. A fixed set of control gains generalized across these activities and users, which minimized the configuration time of the prosthesis.
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Affiliation(s)
- David Quintero
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080 USA
- Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080 USA
| | - Dario J Villarreal
- Department of Electrical Engineering, Southern Methodist University, Dallas, TX 75275 USA
| | - Daniel J Lambert
- Department of Electrical and Computer Engineering, University of Texas at Dallas, Richardson, TX 75080 USA
| | - Susan Kapp
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA 98104 USA
| | - Robert D Gregg
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080 USA
- Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080 USA
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18
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Lorentzen J, Willerslev-Olsen M, Hüche Larsen H, Svane C, Forman C, Frisk R, Farmer SF, Kersting U, Nielsen JB. Feedforward neural control of toe walking in humans. J Physiol 2018; 596:2159-2172. [PMID: 29572934 DOI: 10.1113/jp275539] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 03/12/2018] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Activation of ankle muscles at ground contact during toe walking is unaltered when sensory feedback is blocked or the ground is suddenly dropped. Responses in the soleus muscle to transcranial magnetic stimulation, but not peripheral nerve stimulation, are facilitated at ground contact during toe walking. We argue that toe walking is supported by feedforward control at ground contact. ABSTRACT Toe walking requires careful control of the ankle muscles in order to absorb the impact of ground contact and maintain a stable position of the joint. The present study aimed to clarify the peripheral and central neural mechanisms involved. Fifteen healthy adults walked on a treadmill (3.0 km h-1 ). Tibialis anterior (TA) and soleus (Sol) EMG, knee and ankle joint angles, and gastrocnemius-soleus muscle fascicle lengths were recorded. Peripheral and central contributions to the EMG activity were assessed by afferent blockade, H-reflex testing, transcranial magnetic brain stimulation (TMS) and sudden unloading of the planter flexor muscle-tendon complex. Sol EMG activity started prior to ground contact and remained high throughout stance. TA EMG activity, which is normally seen around ground contact during heel strike walking, was absent. Although stretch of the Achilles tendon-muscle complex was observed after ground contact, this was not associated with lengthening of the ankle plantar flexor muscle fascicles. Sol EMG around ground contact was not affected by ischaemic blockade of large-diameter sensory afferents, or the sudden removal of ground support shortly after toe contact. Soleus motor-evoked potentials elicited by TMS were facilitated immediately after ground contact, whereas Sol H-reflexes were not. These findings indicate that at the crucial time of ankle stabilization following ground contact, toe walking is governed by centrally mediated motor drive rather than sensory driven reflex mechanisms. These findings have implications for our understanding of the control of human gait during voluntary toe walking.
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Affiliation(s)
- Jakob Lorentzen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Maria Willerslev-Olsen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | | | - Christian Svane
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Christian Forman
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Frisk
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Simon Francis Farmer
- Sobell Department of Motor Neuroscience & Movement Disorders, Institute of Neurology, University College London & Department of Clinical Neurology, National Hospital for Neurology and Neurosurgery, London, UK
| | - Uwe Kersting
- Department of sensory-motor interaction, Aalborg university, Aalborg, Denmark
| | - Jens Bo Nielsen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
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19
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Nichols TR. Distributed force feedback in the spinal cord and the regulation of limb mechanics. J Neurophysiol 2018; 119:1186-1200. [PMID: 29212914 PMCID: PMC5899305 DOI: 10.1152/jn.00216.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/03/2023] Open
Abstract
This review is an update on the role of force feedback from Golgi tendon organs in the regulation of limb mechanics during voluntary movement. Current ideas about the role of force feedback are based on modular circuits linking idealized systems of agonists, synergists, and antagonistic muscles. In contrast, force feedback is widely distributed across the muscles of a limb and cannot be understood based on these circuit motifs. Similarly, muscle architecture cannot be understood in terms of idealized systems, since muscles cross multiple joints and axes of rotation and further influence remote joints through inertial coupling. It is hypothesized that distributed force feedback better represents the complex mechanical interactions of muscles, including the stresses in the musculoskeletal network born by muscle articulations, myofascial force transmission, and inertial coupling. Together with the strains of muscle fascicles measured by length feedback from muscle spindle receptors, this integrated proprioceptive feedback represents the mechanical state of the musculoskeletal system. Within the spinal cord, force feedback has excitatory and inhibitory components that coexist in various combinations based on motor task and integrated with length feedback at the premotoneuronal and motoneuronal levels. It is concluded that, in agreement with other investigators, autogenic, excitatory force feedback contributes to propulsion and weight support. It is further concluded that coexistent inhibitory force feedback, together with length feedback, functions to manage interjoint coordination and the mechanical properties of the limb in the face of destabilizing inertial forces and positive force feedback, as required by the accelerations and changing directions of both predator and prey.
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Affiliation(s)
- T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
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20
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Schumacher C, Seyfarth A. Sensor-Motor Maps for Describing Linear Reflex Composition in Hopping. Front Comput Neurosci 2017; 11:108. [PMID: 29230172 PMCID: PMC5707192 DOI: 10.3389/fncom.2017.00108] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 11/13/2017] [Indexed: 11/13/2022] Open
Abstract
In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB), velocity (VFB) and force feedback (FFB) pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort). Therefore, we explore the space describing the blending of the monosynaptic reflex pathway gains. We call this reflex parameter space a sensor-motor map. The sensor-motor maps are used to visualize the functional contribution of sensory pathways in multisensory integration. We further evaluate the robustness of these sensor-motor maps to changes in tendon elasticity, body mass, segment length and ground compliance. The model predicted that different reflex pathway compositions selectively optimize specific hopping characteristics (e.g., performance and efficiency). Both FFB and LFB were pathways that enable hopping. FFB resulted in the largest hopping heights, LFB enhanced hopping efficiency and VFB had the ability to disable hopping. For the tested case, the topology of the sensor-motor maps as well as the location of functionally optimal compositions were invariant to changes in system designs (tendon elasticity, body mass, segment length) or environmental parameters (ground compliance). Our results indicate that different feedback pathway compositions may serve different functional roles. The topology of the sensor-motor map was predicted to be robust against changes in the mechanical system design indicating that the reflex system can use different morphological designs, which does not apply for most robotic systems (for which the control often follows a specific design). Consequently, variations in body mechanics are permitted with consistent compositions of sensory feedback pathways. Given the variability in human body morphology, such variations are highly relevant for human motor control.
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Affiliation(s)
- Christian Schumacher
- Lauflabor Locomotion Laboratory, Centre for Cognitive Science, Institute of Sport Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - André Seyfarth
- Lauflabor Locomotion Laboratory, Centre for Cognitive Science, Institute of Sport Science, Technische Universität Darmstadt, Darmstadt, Germany
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21
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Frisk RF, Jensen P, Kirk H, Bouyer LJ, Lorentzen J, Nielsen JB. Contribution of sensory feedback to plantar flexor muscle activation during push-off in adults with cerebral palsy. J Neurophysiol 2017; 118:3165-3174. [PMID: 28904105 DOI: 10.1152/jn.00508.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/07/2017] [Accepted: 09/07/2017] [Indexed: 12/25/2022] Open
Abstract
Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturbations at the ankle, thereby removing sensory feedback naturally activated during push-off. Reduction of electromyographic (EMG) activity in the soleus muscle caused by unloads was compared and related to kinematics and ankle joint stiffness measurements. Similar measures were obtained after 6 wk of gait training. We found that sensory contribution to soleus EMG activation was reduced in CP adults compared with uninjured adults. The lowest contribution of sensory feedback was found in participants with lowest maximal gait speed. This was related to increased ankle plantar flexor stiffness. Six weeks of gait training did not alter the contribution of sensory feedback. We conclude that exaggerated sensory activity is unlikely to contribute to impaired gait in CP adults, because sensory contribution to muscle activity during gait was reduced compared with in uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait so that a larger part of plantar flexor muscle activity must be generated by descending motor commands.NEW & NOTEWORTHY Findings suggest that adults with cerebral palsy have less contribution of sensory feedback to ongoing soleus muscle activation during push-off than uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait, and/or sensory feedback is less integrated with central motor commands in the activation of spinal motor neurons. Consequently, muscle activation must to a larger extent rely on descending drive, which is already decreased because of the cerebral lesion.
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Affiliation(s)
- Rasmus F Frisk
- Center of Neuroscience, University of Copenhagen, Copenhagen, Denmark; .,University College Zealand, Roskilde, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Peter Jensen
- Center of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Kirk
- Center of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Laurent J Bouyer
- CIRRIS-Department of Rehabilitation, Université Laval, Quebec City, Canada; and
| | - Jakob Lorentzen
- Center of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Jens B Nielsen
- Center of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Elsass Institute, Charlottenlund, Denmark
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22
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Geertsen SS, Willerslev-Olsen M, Lorentzen J, Nielsen JB. Development and aging of human spinal cord circuitries. J Neurophysiol 2017; 118:1133-1140. [PMID: 28566459 DOI: 10.1152/jn.00103.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/25/2017] [Accepted: 05/25/2017] [Indexed: 01/25/2023] Open
Abstract
The neural motor circuitries in the spinal cord receive information from our senses and the rest of the nervous system and translate it into purposeful movements, which allow us to interact with the rest of the world. In this review, we discuss how these circuitries are established during early development and the extent to which they are shaped according to the demands of the body that they control and the environment with which the body has to interact. We also discuss how aging processes and physiological changes in our body are reflected in adaptations of activity in the spinal cord motor circuitries. The complex, multifaceted connectivity of the spinal cord motor circuitries allows them to generate vastly different movements and to adapt their activity to meet new challenges imposed by bodily changes or a changing environment. There are thus plenty of possibilities for adaptive changes in the spinal motor circuitries both early and late in life.
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Affiliation(s)
- Svend Sparre Geertsen
- Neural Control of Movement Research Group, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen N, Denmark.,Department of Nutrition, Exercise, and Sports, University of Copenhagen, Copenhagen N, Denmark; and
| | - Maria Willerslev-Olsen
- Neural Control of Movement Research Group, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen N, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Jakob Lorentzen
- Neural Control of Movement Research Group, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen N, Denmark.,Elsass Institute, Charlottenlund, Denmark
| | - Jens Bo Nielsen
- Neural Control of Movement Research Group, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen N, Denmark; .,Elsass Institute, Charlottenlund, Denmark
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23
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Horslen BC, Inglis JT, Blouin JS, Carpenter MG. Both standing and postural threat decrease Achilles' tendon reflex inhibition from tendon electrical stimulation. J Physiol 2017; 595:4493-4506. [PMID: 28326567 DOI: 10.1113/jp273935] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/15/2017] [Indexed: 02/03/2023] Open
Abstract
KEY POINTS Golgi tendon organs (GTOs) and associated Ib reflexes contribute to standing balance, but the potential impacts of threats to standing balance on Ib reflexes are unknown. Tendon electrical stimulation to the Achilles' tendon was used to probe changes in Ib inhibition in medial gastrocnemius with postural orientation (lying prone vs. upright standing; experiment 1) and height-induced postural threat (standing at low and high surface heights; experiment 2). Ib inhibition was reduced while participants stood upright, compared to lying prone (42.2%); and further reduced when standing in the high, compared to low, threat condition (32.4%). These experiments will impact future research because they demonstrate that tendon electrical stimulation can be used to probe Ib reflexes in muscles engaged in standing balance. These results provide novel evidence that human short-latency GTO-Ib reflexes are dependent upon both task, as evidenced by changes with postural orientation, and context, such as height-induced postural threat during standing. ABSTRACT Golgi tendon organ Ib reflexes are thought to contribute to standing balance control, but it is unknown if they are modulated when people are exposed to a postural threat. We used a novel application of tendon electrical stimulation (TStim) to elicit Ib inhibitory reflexes in the medial gastrocnemius, while actively engaged in upright standing balance, to examine (a) how Ib reflexes to TStim are influenced by upright stance, and (b) the effects of height-induced postural threat on Ib reflexes during standing. TStim evoked short-latency (<47 ms) inhibition apparent in trigger-averaged rectified EMG, which was quantified in terms of area, duration and mean amplitude of inhibition. In order to validate the use of TStim in a standing model, TStim-Ib inhibition was compared from conditions where participants were lying prone vs. standing upright. TStim evoked Ib inhibition in both conditions; however, significant reductions in Ib inhibition area (42.2%) and duration (32.9%) were observed during stance. Postural threat, manipulated by having participants stand at LOW (0.8 m high, 0.6 m from edge) and HIGH (3.2 m, at edge) elevated surfaces, significantly reduced Ib inhibition area (32.4%), duration (16.4%) and amplitude (24.8%) in the HIGH, compared to LOW, threat condition. These results demonstrate TStim is a viable technique for investigating Ib reflexes in standing, and confirm Ib reflexes are modulated with postural orientation. The novel observation of reduced Ib inhibition with elevated postural threat reveals that human Ib reflexes are context dependent, and the human Ib reflex pathways are modulated by threat or emotional processing centres of the CNS.
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Affiliation(s)
- Brian C Horslen
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.,The Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
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24
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Kannape OA, Herr HM. Volitional control of ankle plantar flexion in a powered transtibial prosthesis during stair-ambulation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2014:1662-5. [PMID: 25570293 DOI: 10.1109/embc.2014.6943925] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Although great advances have been made in the design and control of lower extremity prostheses, walking on different terrains, such as ramps or stairs, and transitioning between these terrains remains a major challenge for the field. In order to generalize biomimetic behaviour of active lower-limb prostheses top-down volitional control is required but has until recently been deemed unfeasible due to the difficulties involved in acquiring an adequate electromyographic (EMG) signal. In this study, we hypothesize that a transtibial amputee can extend the functionality of a hybrid controller, designed for level ground walking, to stair ascent and descent by volitionally modulating powered plantar-flexion of the prosthesis. We here present data illustrating that the participant is able to reproduce ankle push-off behaviour of the intrinsic controller during stair ascent as well as prevent inadvertent push-off during stair descent. Our findings suggest that EMG signal from the residual limb muscles can be used to transition between level-ground walking and stair ascent/descent within a single step and significantly improve prosthesis performance during stair-ambulation.
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25
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Lyle MA, Prilutsky BI, Gregor RJ, Abelew TA, Nichols TR. Self-reinnervated muscles lose autogenic length feedback, but intermuscular feedback can recover functional connectivity. J Neurophysiol 2016; 116:1055-67. [PMID: 27306676 DOI: 10.1152/jn.00335.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/09/2016] [Indexed: 12/11/2022] Open
Abstract
In this study, we sought to identify sensory circuitry responsible for motor deficits or compensatory adaptations after peripheral nerve cut and repair. Self-reinnervation of the ankle extensor muscles abolishes the stretch reflex and increases ankle yielding during downslope walking, but it remains unknown whether this finding generalizes to other muscle groups and whether muscles become completely deafferented. In decerebrate cats at least 19 wk after nerve cut and repair, we examined the influence of quadriceps (Q) muscles' self-reinnervation on autogenic length feedback, as well as intermuscular length and force feedback, among the primary extensor muscles in the cat hindlimb. Effects of gastrocnemius and soleus self-reinnervation on intermuscular circuitry were also evaluated. We found that autogenic length feedback was lost after Q self-reinnervation, indicating that loss of the stretch reflex appears to be a generalizable consequence of muscle self-reinnervation. However, intermuscular force and length feedback, evoked from self-reinnervated muscles, was preserved in most of the interactions evaluated with similar relative inhibitory or excitatory magnitudes. These data indicate that intermuscular spinal reflex circuitry has the ability to regain functional connectivity, but the restoration is not absolute. Explanations for the recovery of intermuscular feedback are discussed, based on identified mechanisms responsible for lost autogenic length feedback. Functional implications, due to permanent loss of autogenic length feedback and potential for compensatory adaptations from preserved intermuscular feedback, are discussed.
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Affiliation(s)
- Mark A Lyle
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia;
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Robert J Gregor
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia; Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California; and
| | - Thomas A Abelew
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia; Department of Cell Biology, Emory University, Atlanta, Georgia
| | - T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
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Abstract
Human studies in the past three decades have provided us with an emerging understanding of how cortical and spinal networks collaborate to ensure the vast repertoire of human behaviors. Humans have direct cortical connections to spinal motoneurons, which bypass spinal interneurons and exert a direct (willful) muscle control with the aid of a context-dependent integration of somatosensory and visual information at cortical level. However, spinal networks also play an important role. Sensory feedback through spinal circuitries is integrated with central motor commands and contributes importantly to the muscle activity underlying voluntary movements. Regulation of spinal interneurons is used to switch between motor states such as locomotion (reciprocal innervation) and stance (coactivation pattern). Cortical regulation of presynaptic inhibition of sensory afferents may focus the central motor command by opening or closing sensory feedback pathways. In the future, human studies of spinal motor control, in close collaboration with animal studies on the molecular biology of the spinal cord, will continue to document the neural basis for human behavior.
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Affiliation(s)
- Jens Bo Nielsen
- Department of Neuroscience and Pharmacology and Department of Nutrition, Exercise and Sports, University of Copenhagen, DK-2200 Copenhagen N, Denmark;
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Silva A, Sousa ASP, Silva C, Tavares JMRS, Santos R, Sousa F. Ankle antagonist coactivation in the double-support phase of walking: Stroke vs. healthy subjects. Somatosens Mot Res 2015; 32:153-7. [PMID: 26290312 DOI: 10.3109/08990220.2015.1012492] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
INTRODUCTION Lesions in ipsilateral systems related to postural control in the ipsilesional side may justify the lower performance of stroke subjects during walking. PURPOSE To analyze bilateral ankle antagonist coactivation during double support in stroke subjects. METHODS Sixteen (8 females; 8 males) subjects with a first isquemic stroke and 22 controls (12 females; 10 males) participated in this study. The double-support phase was assessed through ground reaction forces and the electromyography of ankle muscles was assessed in both limbs. RESULTS The ipsilesional limb presented statistically significant differences from the control when assuming specific roles during double support. The tibialis anterior and soleus pair was the one in which this atypical behavior was more pronounced. CONCLUSION The ipsilesional limb presents a dysfunctional behavior when a higher postural control activity was demanded.
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Affiliation(s)
- Augusta Silva
- a Escola Superior de Tecnologia da Saúde do Instituto Politécnico do Porto by Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudos de Movimento e Atividade Humana , Vila Nova de Gaia , Portugal
| | - Andreia S P Sousa
- a Escola Superior de Tecnologia da Saúde do Instituto Politécnico do Porto by Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudos de Movimento e Atividade Humana , Vila Nova de Gaia , Portugal
| | - Cláudia Silva
- a Escola Superior de Tecnologia da Saúde do Instituto Politécnico do Porto by Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudos de Movimento e Atividade Humana , Vila Nova de Gaia , Portugal
| | - João Manuel R S Tavares
- b Instituto de Engenharia Mecânica e Gestão Industrial, Departamento de Engenharia Mecânica, Faculdade de Engenharia, Universidade do Porto , Porto , Portugal
| | - Rubim Santos
- c Escola Superior da Tecnologia de Saúde do Instituto Politécnico do Porto, Área Científica de Física, Centro de Estudos de Movimento e Atividade Humana , Vila Nova de Gaia , Portugal , and
| | - Filipa Sousa
- d Laboratório de Biomecânica do Porto, Faculdade de Desporto , Universidade do Porto , Porto , Portugal
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Prochazka A. Sensory control of normal movement and of movement aided by neural prostheses. J Anat 2015; 227:167-77. [PMID: 26047134 PMCID: PMC4523319 DOI: 10.1111/joa.12311] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2015] [Indexed: 11/27/2022] Open
Abstract
Signals from sensory receptors in muscles and skin enter the central nervous system (CNS), where they contribute to kinaesthesia and the generation of motor commands. Many lines of evidence indicate that sensory input from skin receptors, muscle spindles and Golgi tendon organs play the predominant role in this regard. Yet in spite of over 100 years of research on this topic, some quite fundamental questions remain unresolved. How does the CNS choose to use the ability to control muscle spindle sensitivity during voluntary movements? Do spinal reflexes contribute usefully to load compensation, given that the feedback gain must be quite low to avoid instability? To what extent do signals from skin stretch receptors contribute? This article provides a brief review of various theories, past and present, that address these questions. To what extent has the knowledge gained resulted in clinical applications? Muscles paralyzed as a result of spinal cord injury or stroke can be activated by electrical stimulation delivered by neuroprostheses. In practice, at most two or three sensors can be deployed on the human body, providing only a small fraction of the information supplied by the tens of thousands of sensory receptors in animals. Most of the neuroprostheses developed so far do not provide continuous feedback control. Instead, they switch from one state to another when signals from their one or two sensors meet pre-set thresholds (finite state control). The inherent springiness of electrically activated muscle provides a crucial form of feedback control that helps smooth the resulting movements. In spite of the dissimilarities, parallels can be found between feedback control in neuroprostheses and in animals and this can provide surprising insights in both directions.
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Affiliation(s)
- Arthur Prochazka
- Neuroscience and Mental Health Institute, University of AlbertaEdmonton, AB, Canada
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Buschmann T, Ewald A, von Twickel A, Büschges A. Controlling legs for locomotion-insights from robotics and neurobiology. BIOINSPIRATION & BIOMIMETICS 2015; 10:041001. [PMID: 26119450 DOI: 10.1088/1748-3190/10/4/041001] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Walking is the most common terrestrial form of locomotion in animals. Its great versatility and flexibility has led to many attempts at building walking machines with similar capabilities. The control of walking is an active research area both in neurobiology and robotics, with a large and growing body of work. This paper gives an overview of the current knowledge on the control of legged locomotion in animals and machines and attempts to give walking control researchers from biology and robotics an overview of the current knowledge in both fields. We try to summarize the knowledge on the neurobiological basis of walking control in animals, emphasizing common principles seen in different species. In a section on walking robots, we review common approaches to walking controller design with a slight emphasis on biped walking control. We show where parallels between robotic and neurobiological walking controllers exist and how robotics and biology may benefit from each other. Finally, we discuss where research in the two fields diverges and suggest ways to bridge these gaps.
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Affiliation(s)
- Thomas Buschmann
- Technische Universität München, Institute of Applied Mechanics, Boltzmannstrasse 15, D-85747 Garching, Germany
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Mugge W, Schouten AC, van Hilten JJ, van der Helm FCT. Impaired Inhibitory Force Feedback in Fixed Dystonia. IEEE Trans Neural Syst Rehabil Eng 2015; 24:475-84. [PMID: 25955788 DOI: 10.1109/tnsre.2015.2422892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Complex regional pain syndrome (CRPS) is a multifactorial disorder associated with an aberrant host response to tissue injury. About 25% of CRPS patients suffer poorly understood involuntary sustained muscle contractions associated with dysfunctional reflexes that result in abnormal postures (fixed dystonia). A recent modeling study simulated fixed dystonia (FD) caused by aberrant force feedback. The current study aims to validate this hypothesis by experimentally recording the modulation of reflexive force feedback in patients with FD. CRPS patients with and without FD, patients with FD but without CRPS, as well as healthy controls participated in the experiment. Three task instructions and three perturbation characteristics were used to evoke a wide range of responses to force perturbations. During position tasks ("maintain posture"), healthy subjects as well as patients resisted the perturbations, becoming more stiff than when being relaxed (i.e., the relax task). Healthy subjects and CRPS patients without FD were both more compliant during force tasks ("maintain force") than during relax tasks, meaning they actively gave way to the imposed forces. Remarkably, the patients with FD failed to do so. A neuromuscular model was fitted to the experimental data to separate the distinct contributions of position, velocity and force feedback, as well as co-contraction to the motor behavior. The neuromuscular modeling indicated that inhibitory force feedback is deregulated in patients with FD, for both CRPS and non-CRPS patients. From previously published simulation results and the present experimental study, it is concluded that aberrant force feedback plays a role in fixed dystonia.
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31
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Sousa ASP, Tavares JMRS. Interlimb Coordination During Step-to-Step Transition and Gait Performance. J Mot Behav 2015; 47:563-74. [PMID: 25893693 DOI: 10.1080/00222895.2015.1023391] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Most energy spent in walking is due to step-to-step transitions. During this phase, the interlimb coordination assumes a crucial role to meet the demands of postural and movement control. The authors review studies that have been carried out regarding the interlimb coordination during gait, as well as the basic biomechanical and neurophysiological principles of interlimb coordination. The knowledge gathered from these studies is useful for understanding step-to-step transition during gait from a motor control perspective and for interpreting walking impairments and inefficiency related to pathologies, such as stroke. This review shows that unimpaired walking is characterized by a consistent and reciprocal interlimb influence that is supported by biomechanical models, and spinal and supraspinal mechanisms. This interlimb coordination is perturbed in subjects with stroke.
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Affiliation(s)
- Andreia S P Sousa
- a Escola Superior de Tecnologia da Saúde do Porto, Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudos de Movimento e Atividade Humana , Portugal
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Pfeifer S, Riener R, Vallery H. Knee stiffness estimation in physiological gait. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:1607-10. [PMID: 25570280 DOI: 10.1109/embc.2014.6943912] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During physiological gait, humans continuously modulate their knee stiffness, depending on the demands of the activity and the terrain. A similar functionality could be provided by modern actuators in transfemoral prosthesis. However, quantitative data on how knee stiffness is modulated during physiological gait is still missing. This is likely due to the experimental difficulties associated with identifying knee stiffness by applying perturbations during gait. It is our goal to quantify such stiffness modulation during gait without the need to apply perturbations. Therefore, we have recently presented an approach to quantify knee stiffness from kinematic, kinetic and electromyographic (EMG) measurements, and have validated it in isometric conditions. The goal of this paper is to extend this approach to non-isometric conditions by combining inverse dynamics and EMG measurements, and to quantify physiological stiffness modulation in the example of level-ground walking. We show that stiffness varies substantially throughout a gait cycle, with a stiffness of around 100 Nm/rad during swing phase, and a peak of 450 Nm/rad in stance phase. These quantitative results may be beneficial for design and control of transfemoral prostheses and orthoses that aim to restore physiological function.
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Barthélemy D, Willerslev-Olsen M, Lundell H, Biering-Sørensen F, Nielsen JB. Assessment of transmission in specific descending pathways in relation to gait and balance following spinal cord injury. PROGRESS IN BRAIN RESEARCH 2015; 218:79-101. [DOI: 10.1016/bs.pbr.2014.12.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Müller R, Häufle DFB, Blickhan R. Preparing the leg for ground contact in running: the contribution of feed-forward and visual feedback. ACTA ACUST UNITED AC 2014; 218:451-7. [PMID: 25524978 DOI: 10.1242/jeb.113688] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
While running on uneven ground, humans are able to negotiate visible but also camouflaged changes in ground level. Previous studies have shown that the leg kinematics before touch down change with ground level. The present study experimentally investigated the contributions of visual perception (visual feedback), proprioceptive feedback and feed-forward patterns to the muscle activity responsible for these adaptations. The activity of three bilateral lower limb muscles (m. gastrocnemius medialis, m. tibialis anterior and m. vastus medialis) of nine healthy subjects was recorded during running across visible (drop of 0, -5 and -10 cm) and camouflaged changes in ground level (drop of 0 and -10 cm). The results reveal that at touchdown with longer flight time, m. tibialis anterior activation decreases and m. vastus medialis activation increases purely by feed-forward driven (flight time-dependent) muscle activation patterns, while m. gastrocnemius medialis activation increase is additionally influenced by visual feedback. Thus, feed-forward driven muscle activation patterns are sufficient to explain the experimentally observed adjustments of the leg at touchdown.
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Affiliation(s)
- Roy Müller
- Motionscience, Institute of Sport Sciences, Friedrich Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
| | | | - Reinhard Blickhan
- Motionscience, Institute of Sport Sciences, Friedrich Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
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35
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Layne CS, Chelette AM, Pourmoghaddam A. Impact of altered lower limb proprioception produced by tendon vibration on adaptation to split-belt treadmill walking. Somatosens Mot Res 2014; 32:31-8. [PMID: 25162146 DOI: 10.3109/08990220.2014.949007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
It has been proposed that proprioceptive input is essential to the development of a locomotor body schema that is used to guide the assembly of successful walking. Proprioceptive information is used to signal the need for, and promotion of, locomotor adaptation in response to environmental or internal modifications. The purpose of this investigation was to determine if tendon vibration applied to either the hamstrings or quadriceps of participants experiencing split-belt treadmill walking modified lower limb kinematics during the early adaptation period. Modifications in the adaptive process in response to vibration would suggest that the sensory-motor system had been unsuccessful in down weighting the disruptive proprioceptive input resulting from vibration. Ten participants experienced split-belt walking, with and without vibration, while gait kinematics were obtained with a 12-camera collection system. Bilateral hip, knee, and ankle joint angles were calculated and the first five strides after the split were averaged for each subject to create joint angle waveforms for each of the assessed joints, for each experimental condition. The intralimb variables of stride length, percent stance time, and relative timing between various combinations of peak joint angles were assessed using repeated measures MANOVA. Results indicate that vibration had very little impact on the split-belt walking adaptive process, although quadriceps vibration did significantly reduce percent stance time by 1.78% relative to the no vibration condition. The data suggest that the perceptual-motor system was able to down weight the disrupted proprioceptive input such that the locomotor body schema was able to effectively manage the lower limb patterns of motion necessary to adapt to the changing belt speed. Complementary explanations for the current findings are also discussed.
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Affiliation(s)
- Charles S Layne
- Department of Health and Human Performance, University of Houston , Houston, Texas , USA
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36
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Fey NP, Simon AM, Young AJ, Hargrove LJ. Controlling Knee Swing Initiation and Ankle Plantarflexion With an Active Prosthesis on Level and Inclined Surfaces at Variable Walking Speeds. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2014; 2:2100412. [PMID: 27170878 PMCID: PMC4861549 DOI: 10.1109/jtehm.2014.2343228] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 02/06/2014] [Accepted: 07/20/2014] [Indexed: 11/10/2022]
Abstract
Improving lower-limb prostheses is important to enhance the mobility of amputees. The purpose of this paper is to introduce an impedance-based control strategy (consisting of four novel algorithms) for an active knee and ankle prosthesis and test its generalizability across multiple walking speeds, walking surfaces, and users. The four algorithms increased ankle stiffness throughout stance, decreased knee stiffness during terminal stance, as well as provided powered ankle plantarflexion and knee swing initiation through modifications of equilibrium positions of the ankle and knee, respectively. Seven amputees (knee disarticulation and transfemoral levels) walked at slow, comfortable, and hurried speeds on level and inclined (10°) surfaces. The prosthesis was tuned at their comfortable level ground walking speed. We further quantified trends in prosthetic knee and ankle kinematics, and kinetics across conditions. Subjects modulated their walking speed by ±25% (average) from their comfortable speeds. As speed increased, increasing ankle angles and velocities as well as stance phase ankle power and plantarflexion torque were observed. At slow and comfortable speeds, plantarflexion torque was increased on the incline. At slow and comfortable speeds, stance phase positive knee power was increased and knee torque more flexor on the incline. As speed increased, knee torque became less flexor on the incline. These algorithms were shown to generalize well across speed, produce gait mechanics that compare favorably with non-amputee data, and display evidence of scalable device function. They have the potential to reduce the challenge of clinically configuring such devices and increase their viability during daily use.
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Marques HG, Bharadwaj A, Iida F. From spontaneous motor activity to coordinated behaviour: a developmental model. PLoS Comput Biol 2014; 10:e1003653. [PMID: 25057775 PMCID: PMC4109855 DOI: 10.1371/journal.pcbi.1003653] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 04/18/2014] [Indexed: 01/09/2023] Open
Abstract
In mammals, the developmental path that links the primary behaviours observed during foetal stages to the full fledged behaviours observed in adults is still beyond our understanding. Often theories of motor control try to deal with the process of incremental learning in an abstract and modular way without establishing any correspondence with the mammalian developmental stages. In this paper, we propose a computational model that links three distinct behaviours which appear at three different stages of development. In order of appearance, these behaviours are: spontaneous motor activity (SMA), reflexes, and coordinated behaviours, such as locomotion. The goal of our model is to address in silico four hypotheses that are currently hard to verify in vivo: First, the hypothesis that spinal reflex circuits can be self-organized from the sensor and motor activity induced by SMA. Second, the hypothesis that supraspinal systems can modulate reflex circuits to achieve coordinated behaviour. Third, the hypothesis that, since SMA is observed in an organism throughout its entire lifetime, it provides a mechanism suitable to maintain the reflex circuits aligned with the musculoskeletal system, and thus adapt to changes in body morphology. And fourth, the hypothesis that by changing the modulation of the reflex circuits over time, one can switch between different coordinated behaviours. Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways. Hopping is used as a case study of coordinated behaviour. Our results show that reflex circuits can be self-organized from SMA, and that, once these circuits are in place, they can be modulated to achieve coordinated behaviour. In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.
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Affiliation(s)
| | - Arjun Bharadwaj
- Dept. of Mechanical and Process Engineering, ETH, Zurich, Switzerland
| | - Fumiya Iida
- Dept. of Mechanical and Process Engineering, ETH, Zurich, Switzerland
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38
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Blanchette AK, Noël M, Richards CL, Nadeau S, Bouyer LJ. Modifications in ankle dorsiflexor activation by applying a torque perturbation during walking in persons post-stroke: a case series. J Neuroeng Rehabil 2014; 11:98. [PMID: 24912626 PMCID: PMC4063428 DOI: 10.1186/1743-0003-11-98] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/02/2014] [Indexed: 11/18/2022] Open
Abstract
Background Results obtained in a previous study (Gait Posture 34:358–363, 2011) have shown that, in non-disabled participants, a specific increase in ankle dorsiflexor (Tibialis anterior [TA]) activation can be induced by walking with a torque perturbation that plantarflexes the ankle during the swing phase. After perturbation removal, the increased TA activation persisted temporarily and was associated with a more dorsiflexed ankle during swing. The objective of the present case-series study was to verify if these results can be reproduced in persons post-stroke. Methods Six participants who sustained a stroke walked on a treadmill before, during and after exposure to a torque perturbation applied at the ankle by a robotized ankle-foot orthosis. Spatiotemporal gait parameters, ankle and knee kinematics, and the electromyographic activity of TA and Soleus were recorded. Mean amplitude of the TA burst located around toe off and peak ankle dorsiflexion angle during swing were compared across the 3 walking periods for each participant. Results At the end of the walking period with the perturbation, TA mean amplitude was significantly increased in 4 of the 6 participants. Among these 4 participants, modifications in TA activation persisted after perturbation removal in 3 of them, and led to a statistically significant increase in peak dorsiflexion during swing. Clinical implications This approach may be helpful to evaluate the residual adaptive capacity in the ankle dorsiflexors after a stroke and guide decision-making for the selection of optimal rehabilitation interventions. Future work will investigate the clinical impact of a multiple-session gait training based on this approach in persons presenting a reduced ankle dorsiflexion during the swing phase of walking.
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Affiliation(s)
| | | | | | | | - Laurent J Bouyer
- Multidisciplinary Team in Locomotor Rehabilitation, Canadian Institutes of Health Research, Quebec, Canada.
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Thompson AK, Wolpaw JR. Restoring walking after spinal cord injury: operant conditioning of spinal reflexes can help. Neuroscientist 2014; 21:203-15. [PMID: 24636954 DOI: 10.1177/1073858414527541] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy. Abnormal spinal reflex activity often contributes to these problems. Operant conditioning of spinal reflexes, which can target plasticity to specific reflex pathways, can enhance recovery. In rats in which a right lateral column lesion had weakened right stance and produced an asymmetrical gait, up-conditioning of the right soleus H-reflex, which increased muscle spindle afferent excitation of soleus, strengthened right stance and eliminated the asymmetry. In people with hyperreflexia due to incomplete SCI, down-conditioning of the soleus H-reflex improved walking speed and symmetry. Furthermore, modulation of electromyographic activity during walking improved bilaterally, indicating that a protocol that targets plasticity to a specific pathway can trigger widespread plasticity that improves recovery far beyond that attributable to the change in the targeted pathway. These improvements were apparent to people in their daily lives. They reported walking faster and farther, and noted less spasticity and better balance. Operant conditioning protocols could be developed to modify other spinal reflexes or corticospinal connections; and could be combined with other therapies to enhance recovery in people with SCI or other neuromuscular disorders.
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Affiliation(s)
- Aiko K Thompson
- Helen Hayes Hospital, New York State Department of Health, West Haverstraw, NY, USA Wadsworth Center, New York State Department of Health, Albany, NY, USA Department of Neurology, Neurological Institute, Columbia University, New York, NY, USA Department of Biomedical Sciences, State University of New York, Albany, NY, USA
| | - Jonathan R Wolpaw
- Helen Hayes Hospital, New York State Department of Health, West Haverstraw, NY, USA Wadsworth Center, New York State Department of Health, Albany, NY, USA Department of Neurology, Neurological Institute, Columbia University, New York, NY, USA Department of Biomedical Sciences, State University of New York, Albany, NY, USA
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Wellinghoff MA, Bunchman AM, Dean JC. Gradual mechanics-dependent adaptation of medial gastrocnemius activity during human walking. J Neurophysiol 2014; 111:1120-31. [PMID: 24335207 PMCID: PMC3949234 DOI: 10.1152/jn.00251.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 12/08/2013] [Indexed: 01/13/2023] Open
Abstract
While performing a simple bouncing task, humans modify their preferred movement period and pattern of plantarflexor activity in response to changes in system mechanics. Over time, the preferred movement pattern gradually adapts toward the resonant frequency. The purpose of the present experiments was to determine whether humans undergo a similar process of gradually adapting their stride period and plantarflexor activity after a change in mechanical demand while walking. Participants walked on a treadmill while we measured stride period and plantarflexor activity (medial gastrocnemius and soleus). Plantarflexor activity during stance was divided into a storage phase (30-65% stance) and a return phase (65-100% stance) based on when the Achilles tendon has previously been shown to store and return mechanical energy. Participants walked either on constant inclines (0%, 1%, 5%, 9%) or on a variable incline (0-1%) for which they were unaware of the incline changes. For variable-incline trials, participants walked under both single-task and dual-task conditions in order to vary the cognitive load. Both stride period and plantarflexor activity increased at steeper inclines. During single-task walking, small changes in incline were followed by gradual adaptation of storage-phase medial gastrocnemius activity. However, this adaptation was not present during dual-task walking, indicating some level of cognitive involvement. The observed adaptation may be the result of using afferent feedback in order to optimize the contractile conditions of the plantarflexors during the stance phase. Such adaptation could serve to improve metabolic economy but may be limited in clinical populations with disrupted proprioception.
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Affiliation(s)
- Molly A Wellinghoff
- Division of Physical Therapy, College of Health Professions, Medical University of South Carolina, Charleston, South Carolina; and
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Chen Y, Chen L, Liu R, Wang Y, Chen XY, Wolpaw JR. Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury. J Neurophysiol 2013; 111:1249-58. [PMID: 24371288 DOI: 10.1152/jn.00756.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a "negotiated equilibrium" that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery.
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Affiliation(s)
- Yi Chen
- Wadsworth Center, New York State Department of Health, Albany, New York
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Abstract
Animal movement is immensely varied, from the simplest reflexive responses to the most complex, dexterous voluntary tasks. Here, we focus on the control of movement in mammals, including humans. First, the sensory inputs most closely implicated in controlling movement are reviewed, with a focus on somatosensory receptors. The response properties of the large muscle receptors are examined in detail. The role of sensory input in the control of movement is then discussed, with an emphasis on the control of locomotion. The interaction between central pattern generators and sensory input, in particular in relation to stretch reflexes, timing, and pattern forming neuronal networks is examined. It is proposed that neural signals related to bodily velocity form the basic descending command that controls locomotion through specific and well-characterized relationships between muscle activation, step cycle phase durations, and biomechanical outcomes. Sensory input is crucial in modulating both the timing and pattern forming parts of this mechanism.
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Affiliation(s)
- Arthur Prochazka
- Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada
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Hof AL, Duysens J. Responses of human hip abductor muscles to lateral balance perturbations during walking. Exp Brain Res 2013; 230:301-10. [PMID: 23934442 DOI: 10.1007/s00221-013-3655-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 07/19/2013] [Indexed: 10/26/2022]
Abstract
Lateral stability during gait is of utmost importance to maintain balance. This was studied on human subjects walking on a treadmill who were given 100-ms perturbations of known magnitude and timing with respect to the gait cycle by means of a computer-controlled pneumatic device. This method has the advantage that the same perturbations can be given at different phases of the stride cycle, thereby allowing an analysis of the phase dependency of the responses in the primary muscles involved. After an inward push, e.g., a push toward the left during right stance, the left foot in the step to follow is placed more to the left (outward strategy). The hypothesis was that this movement is caused by automatic unvoluntary muscle activity. This turned out to be the case: the abduction movement follows EMG responses in the left abductor muscle, gluteus medius, in response to the push. Two responses, with latencies of 100 and 170 ms, and a late reaction >270 ms can be discerned. All three responses are phase dependent; they show facilitation in swing and no response in stance, in contrast to the normal walking activity (background). This independence of the background activity suggests a premotoneuronal gating of these responses, reminiscent of phase-dependent modulation of electrically elicited reflexes. It is concluded that facilitating pathways are opened independent of normal background activation to enable appropriate actions to restore balance after a mediolateral perturbation.
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Affiliation(s)
- A L Hof
- Center for Human Movement Sciences, University of Groningen, PO Box 196, 9700 AD, Groningen, The Netherlands,
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Mugge W, Abbink DA, Schouten AC, van der Helm FCT, Arendzen JH, Meskers CGM. Force control in the absence of visual and tactile feedback. Exp Brain Res 2012; 224:635-45. [PMID: 23223780 DOI: 10.1007/s00221-012-3341-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 11/06/2012] [Indexed: 10/27/2022]
Abstract
Motor control tasks like stance or object handling require sensory feedback from proprioception, vision and touch. The distinction between tactile and proprioceptive sensors is not frequently made in dynamic motor control tasks, and if so, mostly based on signal latency. We previously found that force control tasks entail more compliant behavior than a passive, relaxed condition and by neuromuscular modeling we were able to attribute this to adaptations in proprioceptive force feedback from Golgi tendon organs. This required the assumption that both tactile and visual feedback are too slow to explain the measured adaptations in face of unpredictable force perturbations. Although this assumption was shown to hold using model simulations, so far no experimental data is available to validate it. Here we applied a systematic approach using continuous perturbations and engineering analyses to provide experimental evidence for the hypothesis that motor control adaptation in force control tasks can be achieved using proprioceptive feedback only. Varying task instruction resulted in substantial adaptations in neuromuscular behavior, which persisted after eliminating visual and/or tactile feedback by a nerve block of the nervus plantaris medialis. It is concluded that proprioception adapts dynamic human ankle motor control even in the absence of visual and tactile feedback.
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Affiliation(s)
- Winfred Mugge
- Department of BioMechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands.
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Sousa ASP, Silva A, Tavares JMRS. Biomechanical and neurophysiological mechanisms related to postural control and efficiency of movement: a review. Somatosens Mot Res 2012; 29:131-43. [PMID: 23094940 DOI: 10.3109/08990220.2012.725680] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Understanding postural control requires considering various mechanisms underlying a person's ability to stand, to walk, and to interact with the environment safely and efficiently. The purpose of this paper is to summarize the functional relation between biomechanical and neurophysiological perspectives related to postural control in both standing and walking based on movement efficiency. Evidence related to the biomechanical and neurophysiological mechanisms is explored as well as the role of proprioceptive input on postural and movement control.
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Affiliation(s)
- Andreia S P Sousa
- Escola Superior da Tecnologia de Saúde do Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudos de Movimento e Actividade Humana, Vila Nova de Gaia, Portugal
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Pang MY, Mak MK. Influence of contraction type, speed, and joint angle on ankle muscle weakness in Parkinson's disease: implications for rehabilitation. Arch Phys Med Rehabil 2012; 93:2352-9. [PMID: 22705465 DOI: 10.1016/j.apmr.2012.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 04/18/2012] [Accepted: 06/04/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE To compare the ankle muscle strength and torque-angle relationship between individuals with Parkinson's disease (PD) and participants without impairments. DESIGN Cross-sectional, exploratory study. SETTING Motor control laboratory in a university. PARTICIPANTS Convenience sample of community-dwelling individuals with PD (n=59) recruited from a PD self-help group and age-matched participants without impairments (n=37) recruited from community older adult centers. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURE Peak torque and angle-torque profile during concentric and eccentric contraction of ankle dorsiflexors and plantarflexors at 2 different angular speeds (45 and 90°/s). RESULTS The PD group displayed lower muscle peak torque values than participants without impairments in all test conditions. Generally, concentric strength was more compromised, with a greater between-group difference (Cohen d=1.29-1.60) than eccentric strength (Cohen d=.81-1.37). Significant group by angular speed interaction was observed in ankle plantarflexion concentric peak torque (P<.001), indicating that muscle weakness was more pronounced when the angular speed was increased. The group by joint angle interaction in concentric contraction of ankle plantarflexors at 90°/s was also significant (P<.001), revealing that the between-group difference in torque values became increasingly more pronounced when the joint was moving toward the end range of the ankle plantarflexion. This exaggerated ankle plantarflexor muscle weakness at the end range was significantly correlated with clinical balance measures (P<.05). CONCLUSIONS Muscle weakness in PD is influenced by contraction type, angular speed, and joint range. Exaggerated weakness is found in concentric contraction of ankle plantarflexors, particularly when the angular speed is high and the muscle is in shortened lengths.
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Affiliation(s)
- Marco Y Pang
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong.
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Sousa ASP, Santos R, Oliveira FPM, Carvalho P, Tavares JMRS. Analysis of ground reaction force and electromyographic activity of the gastrocnemius muscle during double support. Proc Inst Mech Eng H 2012; 226:397-405. [DOI: 10.1177/0954411912439671] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mechanisms associated with energy expenditure during gait have been extensively researched and studied. According to the double-inverted pendulum model energy expenditure is higher during double support, as lower limbs need to work to redirect the centre of mass velocity. This study looks into how the ground reaction force of one limb affects the muscle activity required by the medial gastrocnemius of the contralateral limb during step-to-step transition. Thirty-five subjects were monitored as to the medial gastrocnemius electromyographic activity of one limb and the ground reaction force of the contralateral limb during double support. After determination of the Pearson correlation coefficient (r), a moderate correlation was observed between the medial gastrocnemius electromyographic activity of the dominant leg and the vertical (Fz) and anteroposterior (Fy) components of ground reaction force of the non-dominant leg (r = 0.797, p < 0.0001; r = –0.807, p < 0.0001). A weak and moderate correlation was observed between the medial gastrocnemius electromyographic activity of the non-dominant leg and the Fz and Fy of the dominant leg, respectively (r = 0.442, p = 0.018; r = –0.684 p < 0.0001). The results obtained suggest that during double support, ground reaction force is associated with the electromyographic activity of the contralateral medial gastrocnemius and that there is an increased dependence between the ground reaction force of the non-dominant leg and the electromyographic activity of the dominant medial gastrocnemius.
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Affiliation(s)
- Andreia SP Sousa
- Área Científica de Fisioterapia, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
| | - Rubim Santos
- Departamento de Física, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Portugal
| | - Francisco PM Oliveira
- Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
| | - Paulo Carvalho
- Departamento de Fisioterapia, Centro de Estudos de Movimento e Actividade Humana, Escola Superior de Tecnologia da Saúde do Porto, Portugal
| | - João Manuel RS Tavares
- Instituto de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia, Universidade do Porto, Portugal
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Hellekes K, Blincow E, Hoffmann J, Büschges A. Control of reflex reversal in stick insect walking: effects of intersegmental signals, changes in direction, and optomotor-induced turning. J Neurophysiol 2012; 107:239-49. [DOI: 10.1152/jn.00718.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In many animals, the effects of sensory feedback on motor output change during locomotion. These changes can occur as reflex reversals in which sense organs that activate muscles to counter perturbations in posture control instead reinforce movements in walking. The mechanisms underlying these changes are only partially understood. As such, it is unclear whether reflex reversals are modulated when locomotion is adapted, such as during changes in walking direction or in turning movements. We investigated these questions in the stick insect Carausius morosus, where sensory signals from the femoral chordotonal organ are known to produce resistance reflexes at rest but assistive movements during walking. We studied how intersegmental signals from neighboring legs affect the generation of reflex reversals in a semi-intact preparation that allows free leg movement during walking. We found that reflex reversal was enhanced by stepping activity of the ipsilateral neighboring rostral leg, whereas stepping of contralateral legs had no effect. Furthermore, we found that the occurrence of reflex reversals was task-specific: in the front legs of animals with five legs walking, reflex reversal was generated only during forward and not backward walking. Similarly, during optomotor-induced curved walking, reflex reversal occurred only in the middle leg on the inside of the turn and not in the contralateral leg on the outside of the turn. Thus our results show for the first time that the nervous system modulates reflexes in individual legs in the adaptation of walking to specific tasks.
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Affiliation(s)
- Katja Hellekes
- Department of Animal Physiology, Zoological Institute, Biocenter Cologne, University of Cologne, Cologne, Germany
| | - Eric Blincow
- Department of Animal Physiology, Zoological Institute, Biocenter Cologne, University of Cologne, Cologne, Germany
| | - Julia Hoffmann
- Department of Animal Physiology, Zoological Institute, Biocenter Cologne, University of Cologne, Cologne, Germany
| | - Ansgar Büschges
- Department of Animal Physiology, Zoological Institute, Biocenter Cologne, University of Cologne, Cologne, Germany
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Modeling movement disorders—CRPS-related dystonia explained by abnormal proprioceptive reflexes. J Biomech 2012; 45:90-8. [DOI: 10.1016/j.jbiomech.2011.09.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 08/17/2011] [Accepted: 09/28/2011] [Indexed: 11/21/2022]
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50
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Markowitz J, Krishnaswamy P, Eilenberg MF, Endo K, Barnhart C, Herr H. Speed adaptation in a powered transtibial prosthesis controlled with a neuromuscular model. Philos Trans R Soc Lond B Biol Sci 2011; 366:1621-31. [PMID: 21502131 DOI: 10.1098/rstb.2010.0347] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Control schemes for powered ankle-foot prostheses would benefit greatly from a means to make them inherently adaptive to different walking speeds. Towards this goal, one may attempt to emulate the intact human ankle, as it is capable of seamless adaptation. Human locomotion is governed by the interplay among legged dynamics, morphology and neural control including spinal reflexes. It has been suggested that reflexes contribute to the changes in ankle joint dynamics that correspond to walking at different speeds. Here, we use a data-driven muscle-tendon model that produces estimates of the activation, force, length and velocity of the major muscles spanning the ankle to derive local feedback loops that may be critical in the control of those muscles during walking. This purely reflexive approach ignores sources of non-reflexive neural drive and does not necessarily reflect the biological control scheme, yet can still closely reproduce the muscle dynamics estimated from biological data. The resulting neuromuscular model was applied to control a powered ankle-foot prosthesis and tested by an amputee walking at three speeds. The controller produced speed-adaptive behaviour; net ankle work increased with walking speed, highlighting the benefits of applying neuromuscular principles in the control of adaptive prosthetic limbs.
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Affiliation(s)
- Jared Markowitz
- Biomechatronics Group, Massachusetts Institute of Technology, 75 Amherst Street, Cambridge, MA 02139, USA
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