1
|
Hüche Larsen H, Justiniano MD, Frisk RF, Lundbye-Jensen J, Farmer SF, Nielsen JB. Task difficulty of visually guided gait modifications involves differences in central drive to spinal motor neurons. J Neurophysiol 2024; 132:1126-1141. [PMID: 39196679 DOI: 10.1152/jn.00466.2023] [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: 12/17/2023] [Revised: 08/16/2024] [Accepted: 08/21/2024] [Indexed: 08/30/2024] Open
Abstract
Walking in natural environments requires visually guided modifications, which can be more challenging when involving sideways steps rather than longer steps. This exploratory study investigated whether these two types of modifications involve different changes in the central drive to spinal motor neurons of leg muscles. Fifteen adults [age: 36 ± 6 (SD) years] walked on a treadmill (4 km/h) while observing a screen displaying the real-time position of their toes. At the beginning of the swing phase, a visual target appeared in front (forward) or medial-lateral (sideways) of the ground contact in random step cycles (approximately every third step). We measured three-dimensional kinematics and electromyographic activity from leg muscles bilaterally. Intermuscular coherence was calculated in the alpha (5-15 Hz), beta (15-30 Hz), and gamma bands (30-45 Hz) approximately 230 ms before and after ground contact in control and target steps. Results showed that adjustments toward sideways targets were associated with significantly higher error, lower foot lift, and higher cocontraction between antagonist ankle muscles. Movements toward sideways targets were associated with larger beta-band soleus (SOL): medial gastrocnemius (MG) coherence and a more narrow and larger peak of synchronization in the cumulant density before ground contact. In contrast, movements toward forward targets showed no significant differences in coherence or synchronization compared with control steps. Larger SOL:MG beta-band coherence and short-term synchronization were observed during sideways, but not forward, gait modifications. This suggests that visually guided gait modifications may involve differences in the central drive to spinal ankle motor neurons dependent on the level of task difficulty.NEW & NOTEWORTHY This exploratory study suggests a specific and temporally restricted increase of central (likely corticospinal) drive to ankle muscles in relation to visually guided gait modifications. The findings indicate that a high level of visual attention to control the position of the ankle joint precisely before ground contact may involve increased central drive to ankle muscles. These findings are important for understanding the neural mechanisms underlying visually guided gait and may help develop rehabilitation interventions.
Collapse
Affiliation(s)
- Helle Hüche Larsen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
- Elsass Foundation, Charlottenlund, Denmark
| | | | - Rasmus Feld Frisk
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
- Elsass Foundation, Charlottenlund, Denmark
| | - Jesper Lundbye-Jensen
- Movement and Neuroscience, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Simon Francis Farmer
- Department of Clinical and Movement Neuroscience, Institute of Neurology, University College London, London, United Kingdom
- Department of Clinical Neurology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
| | - Jens Bo Nielsen
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
- Elsass Foundation, Charlottenlund, Denmark
| |
Collapse
|
2
|
da Silva Costa AA, Moraes R, den Otter R, Gennaro F, Bakker L, Rocha Dos Santos PC, Hortobágyi T. Corticomuscular and intermuscular coherence as a function of age and walking balance difficulty. Neurobiol Aging 2024; 141:85-101. [PMID: 38850592 DOI: 10.1016/j.neurobiolaging.2024.05.004] [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: 09/25/2023] [Revised: 04/12/2024] [Accepted: 05/08/2024] [Indexed: 06/10/2024]
Abstract
We determined beta-band intermuscular (IMC) and corticomuscular coherence (CMC) as a function of age and walking balance difficulty. Younger (n=14, 23y) and older individuals (n=19, 71y) walked 13 m overground, on a 6-cm-wide ribbon overground, and on a 6-cm-wide (5-cm-high) beam. Walking distance as a proxy for walking balance and speed were computed. CMC was estimated between electroencephalographic signal at Cz electrode and surface electromyographic signals of seven leg muscles, while IMC was calculated in four pairs of leg muscles, during stance and swing gait phases. With increasing difficulty, walking balance decreased in old individuals and speed decreased gradually independent of age. Beam walking increased IMC, while age increased IMC in proximal muscle pairs, and decreased IMC in distal muscle pairs. Age and difficulty increased CMC independent of gait phases. Concluding, CMC and IMC increased with walking balance difficulty and age, except for distal muscle pairs, which had lower IMC with age. These findings suggest an age-related increase in corticospinal involvement in the neural control of walking balance. DATA AVAILABILITY: The datasets used in this study are available from the corresponding author upon reasonable request.
Collapse
Affiliation(s)
- Andréia Abud da Silva Costa
- Ribeirão Preto Medical School, Graduate Program in Rehabilitation and Functional Performance, University of São Paulo, Brazil; Biomechanics and Motor Control Lab, School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Brazil; Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands.
| | - Renato Moraes
- Ribeirão Preto Medical School, Graduate Program in Rehabilitation and Functional Performance, University of São Paulo, Brazil; Biomechanics and Motor Control Lab, School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, Brazil
| | - Rob den Otter
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Federico Gennaro
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Lisanne Bakker
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Paulo Cezar Rocha Dos Santos
- Department of Computer Science & Applied Mathematics, Weizmann Institute of Science, Israel; The Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Israel; IDOR/Pioneer Science Initiative, Rio de Janeiro, RJ, Brazil
| | - Tibor Hortobágyi
- Department of Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands; Department of Kinesiology, Hungarian University of Sports Science, Budapest 1123, Hungary; Department of Sport Biology, Institute of Sport Sciences and Physical Education, University of Pécs, Pécs, Hungary
| |
Collapse
|
3
|
Roeder L, Breakspear M, Kerr GK, Boonstra TW. Dynamics of brain-muscle networks reveal effects of age and somatosensory function on gait. iScience 2024; 27:109162. [PMID: 38414847 PMCID: PMC10897916 DOI: 10.1016/j.isci.2024.109162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/16/2023] [Accepted: 02/05/2024] [Indexed: 02/29/2024] Open
Abstract
Walking is a complex motor activity that requires coordinated interactions between the sensory and motor systems. We used mobile EEG and EMG to investigate the brain-muscle networks involved in gait control during overground walking in young people, older people, and individuals with Parkinson's disease. Dynamic interactions between the sensorimotor cortices and eight leg muscles within a gait cycle were assessed using multivariate analysis. We identified three distinct brain-muscle networks during a gait cycle. These networks include a bilateral network, a left-lateralized network activated during the left swing phase, and a right-lateralized network active during the right swing. The trajectories of these networks are contracted in older adults, indicating a reduction in neuromuscular connectivity with age. Individuals with the impaired tactile sensitivity of the foot showed a selective enhancement of the bilateral network, possibly reflecting a compensation strategy to maintain gait stability. These findings provide a parsimonious description of interindividual differences in neuromuscular connectivity during gait.
Collapse
Affiliation(s)
- Luisa Roeder
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
- School of Information Systems, Faculty of Science, Queensland University of Technology, Brisbane, QLD, Australia
- Chair of Human Movement Science, Department of Sport and Health Sciences, Technical University of Munich, Munich, Germany
| | - Michael Breakspear
- College of Engineering Science and Environment, College of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia
| | - Graham K Kerr
- School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
| | - Tjeerd W Boonstra
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands
| |
Collapse
|
4
|
Zipser-Mohammadzada F, Scheffers MF, Conway BA, Halliday DM, Zipser CM, Curt A, Schubert M. Intramuscular coherence enables robust assessment of modulated supra-spinal input in human gait: an inter-dependence study of visual task and walking speed. Exp Brain Res 2023; 241:1675-1689. [PMID: 37199775 DOI: 10.1007/s00221-023-06635-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 05/11/2023] [Indexed: 05/19/2023]
Abstract
Intramuscular high-frequency coherence is increased during visually guided treadmill walking as a consequence of increased supra-spinal input. The influence of walking speed on intramuscular coherence and its inter-trial reproducibility need to be established before adoption as a functional gait assessment tool in clinical settings. Here, fifteen healthy controls performed a normal and a target walking task on a treadmill at various speeds (0.3 m/s, 0.5 m/s, 0.9 m/s, and preferred) during two sessions. Intramuscular coherence was calculated between two surface EMG recordings sites of the Tibialis anterior muscle during the swing phase of walking. The results were averaged across low-frequency (5-14 Hz) and high-frequency (15-55 Hz) bands. The effect of speed, task, and time on mean coherence was assessed using three-way repeated measures ANOVA. Reliability and agreement were calculated with the intra-class correlation coefficient and Bland-Altman method, respectively. Intramuscular coherence during target walking was significantly higher than during normal walking across all walking speeds in the high-frequency band as obtained by the three-way repeated measures ANOVA. Interaction effects between task and speed were found for the low- and high-frequency bands, suggesting that task-dependent differences increase at higher walking speeds. Reliability of intramuscular coherence was moderate to excellent for most normal and target walking tasks in all frequency bands. This study confirms previous reports of increased intramuscular coherence during target walking, while providing first evidence for reproducibility and robustness of this measure as a requirement to investigate supra-spinal input.Trial registration Registry number/ClinicalTrials.gov Identifier: NCT03343132, date of registration 2017/11/17.
Collapse
Affiliation(s)
| | - Marjelle Fredie Scheffers
- Department of Neurophysiology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland
- Faculty of Medicine, Utrecht University, Utrecht, The Netherlands
| | - Bernard A Conway
- Biomedical Engineering, University of Strathclyde, Glasgow, G4 0NW, UK
| | - David M Halliday
- School of Physics, Engineering and Technology, University of York, York, YO10 5DD, UK
- York Biomedical Research Institute, University of York, York, UK
| | - Carl Moritz Zipser
- Department of Neurophysiology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland
| | - Armin Curt
- Department of Neurophysiology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland
| | - Martin Schubert
- Department of Neurophysiology, Spinal Cord Injury Center, Balgrist University Hospital, Zurich, Switzerland
| |
Collapse
|
5
|
Yamanaka E, Horiuchi Y, Nojima I. EMG-EMG coherence during voluntary control of human standing tasks: a systematic scoping review. Front Neurosci 2023; 17:1145751. [PMID: 37250422 PMCID: PMC10215561 DOI: 10.3389/fnins.2023.1145751] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
Background Intra- or inter-muscular (EMG-EMG) coherence is a simple and non-invasive method for estimating central nervous system control during human standing tasks. Although this research area has developed, no systematic literature review has been conducted. Objectives We aimed to map the current literature on EMG-EMG coherence during various standing tasks to identify the research gaps and summarize previous studies comparing EMG-EMG coherence between healthy young and elderly adults. Methods Electronic databases (PubMed, Cochrane Library, and CINAHL) were searched for articles published from inception to December 2021. We incorporated studies that analyzed EMG-EMG coherence of the postural muscles in various standing tasks. Results Finally, 25 articles fulfilled the inclusion criteria and involved 509 participants. Most participants were healthy young adults, while only one study included participants with medical conditions. There was some evidence that EMG-EMG coherence could identify differences in standing control between healthy young and elderly adults, although the methodology was highly heterogeneous. Conclusion The present review indicates that EMG-EMG coherence may help elucidate changes in standing control with age. In future studies, this method should be used in participants with central nervous system disorders to understand better the characteristics of standing balance disabilities.
Collapse
Affiliation(s)
- Eiji Yamanaka
- Division of Physical Therapy, Shinshu University School of Health Sciences, Nagano, Japan
- Department of Rehabilitation Medicine, Tokyo Bay Rehabilitation Hospital, Chiba, Japan
| | - Yuki Horiuchi
- Division of Physical Therapy, Shinshu University School of Health Sciences, Nagano, Japan
| | - Ippei Nojima
- Division of Physical Therapy, Shinshu University School of Health Sciences, Nagano, Japan
| |
Collapse
|
6
|
Estimation of Time-Frequency Muscle Synergy in Wrist Movements. ENTROPY 2022; 24:e24050707. [PMID: 35626589 PMCID: PMC9140749 DOI: 10.3390/e24050707] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/09/2022] [Accepted: 04/25/2022] [Indexed: 02/05/2023]
Abstract
Muscle synergy analysis is a kind of modularized decomposition of muscles during exercise controlled by the central nervous system (CNS). It can not only extract the synergistic muscles in exercise, but also obtain the activation states of muscles to reflect the coordination and control relationship between muscles. However, previous studies have mainly focused on the time-domain synergy without considering the frequency-specific characteristics within synergy structures. Therefore, this study proposes a novel method, named time-frequency non-negative matrix factorization (TF-NMF), to explore the time-varying regularity of muscle synergy characteristics of multi-channel surface electromyogram (sEMG) signals at different frequency bands. In this method, the wavelet packet transform (WPT) is used to transform the time-scale signals into time-frequency dimension. Then, the NMF method is calculated in each time-frequency window to extract the synergy modules. Finally, this method is used to analyze the sEMG signals recorded from 8 muscles during the conversion between wrist flexion (WF stage) and wrist extension (WE stage) movements in 12 healthy people. The experimental results show that the number of synergy modules in wrist flexion transmission to wrist extension (Motion Conversion, MC stage) is more than that in the WF stage and WE stage. Furthermore, the number of flexor and extensor muscle synergies in the frequency band of 0–125 Hz during the MC stage is more than that in the frequency band of 125–250 Hz. Further analysis shows that the flexion muscle synergies mostly exist in the frequency band of 140.625–156.25 Hz during the WF stage, and the extension muscle synergies appear in the frequency band of 125–156.25 Hz during the WE stage. These results can help to better understand the time-frequency features of muscle synergy, and expand study perspective related to motor control in nervous system.
Collapse
|
7
|
Zaback M, Adkin AL, Chua R, Timothy Inglis J, Carpenter MG. Facilitation and habituation of cortical and subcortical control of standing balance following repeated exposure to a height-related postural threat. Neuroscience 2022; 487:8-25. [DOI: 10.1016/j.neuroscience.2022.01.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 12/23/2021] [Accepted: 01/17/2022] [Indexed: 01/21/2023]
|
8
|
Tian N, Chen Y, Sun W, Liu H, Wang X, Yan T, Song R. Investigating the Stroke- and Aging-Related Changes in Global and Instantaneous Intermuscular Coupling Using Cross-Fuzzy Entropy. IEEE Trans Neural Syst Rehabil Eng 2021; 29:1573-1582. [PMID: 34329167 DOI: 10.1109/tnsre.2021.3101615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Intermuscular coupling is essential in the coordination of agonist and antagonist muscles. However, its dynamic characteristics are not fully understood, especially the alterations of intermuscular coupling induced by stroke and aging. This study aimed to investigate the aging- and stroke-related changes in the global and instantaneous intermuscular coupling between agonist and antagonist muscles. In the experiment, 8 patients after stroke, 18 healthy young subjects and 10 healthy middle-aged subjects were recruited and instructed to finish the elbow flexion and extension tasks. Cross-fuzzy entropy (C-FuzzyEn) and instantaneous C-FuzzyEn ( [Formula: see text]-FuzzyEn) based on a sliding window were used to analyze the global and instantaneous intermuscular coupling, respectively. Instantaneous FuzzyEn ( i -FuzzyEn) based on a sliding window was also applied to investigate the dynamic complexity of the EMG segment. Pearson correlation analysis revealed that i -FuzzyEn values were negatively correlated with [Formula: see text]-FuzzyEn values in most cases, which implied that there was a positive correlation between EMG complexity and intermuscular coupling. The C-FuzzyEn values between agonist and antagonist muscles increased significantly in both tasks of the patients after stroke than those of the healthy subjects (p < 0.05), which might be due to the decrease in intermuscular coupling induced by the damage of the corticospinal pathways after stroke. The combined application of C-FuzzyEn, [Formula: see text]-FuzzyEn and i -FuzzyEn provides a more comprehensive understanding of the global and instantaneous intermuscular coupling.
Collapse
|
9
|
Weersink JB, de Jong BM, Halliday DM, Maurits NM. Intermuscular coherence analysis in older adults reveals that gait-related arm swing drives lower limb muscles via subcortical and cortical pathways. J Physiol 2021; 599:2283-2298. [PMID: 33687081 PMCID: PMC8252748 DOI: 10.1113/jp281094] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/26/2021] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Gait-related arm swing in humans supports efficient lower limb muscle activation, indicating a neural coupling between the upper and lower limbs during gait. Intermuscular coherence analyses of gait-related electromyography from upper and lower limbs in 20 healthy participants identified significant coherence in alpha and beta/gamma bands indicating that upper and lower limbs share common subcortical and cortical drivers that coordinate the rhythmic four-limb gait pattern. Additional directed connectivity analyses revealed that upper limb muscles drive and shape lower limb muscle activity during gait via subcortical and cortical pathways and to a lesser extent vice versa. The results provide a neural underpinning that arm swing may serve as an effective rehabilitation therapy concerning impaired gait in neurological diseases. ABSTRACT Human gait benefits from arm swing, as it enhances efficient lower limb muscle activation in healthy participants as well as patients suffering from neurological impairment. The underlying neuronal mechanisms of such coupling between upper and lower limbs remain poorly understood. The aim of the present study was to examine this coupling by intermuscular coherence analysis during gait. Additionally, directed connectivity analysis of this coupling enabled assessment of whether gait-related arm swing indeed drives lower limb muscles. To that end, electromyography recordings were obtained from four lower limb muscles and two upper limb muscles bilaterally, during gait, of 20 healthy participants (mean (SD) age 67 (6.8) years). Intermuscular coherence analysis revealed functional coupling between upper and lower limb muscles in the alpha and beta/gamma band during muscle specific periods of the gait cycle. These effects in the alpha and beta/gamma bands indicate involvement of subcortical and cortical sources, respectively, that commonly drive the rhythmic four-limb gait pattern in an efficiently coordinated fashion. Directed connectivity analysis revealed that upper limb muscles drive and shape lower limb muscle activity during gait via subcortical and cortical pathways and to a lesser extent vice versa. This indicates that gait-related arm swing reflects the recruitment of neuronal support for optimizing the cyclic movement pattern of the lower limbs. These findings thus provide a neural underpinning for arm swing to potentially serve as an effective rehabilitation therapy concerning impaired gait in neurological diseases.
Collapse
Affiliation(s)
- Joyce B Weersink
- Department of Neurology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, POB 30.001, Groningen, The Netherlands
| | - Bauke M de Jong
- Department of Neurology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, POB 30.001, Groningen, The Netherlands
| | - David M Halliday
- Department of Electronic Engineering & York Biomedical Research Institute, University of York, York, YO10 5DD, UK
| | - Natasha M Maurits
- Department of Neurology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, POB 30.001, Groningen, The Netherlands
| |
Collapse
|
10
|
Watanabe T, Nojima I, Mima T, Sugiura H, Kirimoto H. Magnification of visual feedback modulates corticomuscular and intermuscular coherences differently in young and elderly adults. Neuroimage 2020; 220:117089. [DOI: 10.1016/j.neuroimage.2020.117089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/05/2020] [Accepted: 06/21/2020] [Indexed: 10/24/2022] Open
|
11
|
Kenville R, Maudrich T, Vidaurre C, Maudrich D, Villringer A, Ragert P, Nikulin VV. Intermuscular coherence between homologous muscles during dynamic and static movement periods of bipedal squatting. J Neurophysiol 2020; 124:1045-1055. [PMID: 32816612 PMCID: PMC7742219 DOI: 10.1152/jn.00231.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Coordination of functionally coupled muscles is a key aspect of movement execution. Demands on coordinative control increase with the number of involved muscles and joints, as well as with differing movement periods within a given motor sequence. While previous research has provided evidence concerning inter- and intramuscular synchrony in isolated movements, compound movements remain largely unexplored. With this study, we aimed to uncover neural mechanisms of bilateral coordination through intermuscular coherence (IMC) analyses between principal homologous muscles during bipedal squatting (BpS) at multiple frequency bands (alpha, beta, and gamma). For this purpose, participants performed bipedal squats without additional load, which were divided into three distinct movement periods (eccentric, isometric, and concentric). Surface electromyography (EMG) was recorded from four homologous muscle pairs representing prime movers during bipedal squatting. We provide novel evidence that IMC magnitudes differ between movement periods in beta and gamma bands, as well as between homologous muscle pairs across all frequency bands. IMC was greater in the muscle pairs involved in postural and bipedal stability compared with those involved in muscular force during BpS. Furthermore, beta and gamma IMC magnitudes were highest during eccentric movement periods, whereas we did not find movement-related modulations for alpha IMC magnitudes. This finding thus indicates increased integration of afferent information during eccentric movement periods. Collectively, our results shed light on intermuscular synchronization during bipedal squatting, as we provide evidence that central nervous processing of bilateral intermuscular functioning is achieved through task-dependent modulations of common neural input to homologous muscles. NEW & NOTEWORTHY It is largely unexplored how the central nervous system achieves coordination of homologous muscles of the upper and lower body within a compound whole body movement, and to what extent this neural drive is modulated between different movement periods and muscles. Using intermuscular coherence analysis, we show that homologous muscle functions are mediated through common oscillatory input that extends over alpha, beta, and gamma frequencies with different synchronization patterns at different movement periods.
Collapse
Affiliation(s)
- Rouven Kenville
- Institute for General Kinesiology and Exercise Science, Faculty of Sports Science, University of Leipzig, Leipzig, Germany.,Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany
| | - Tom Maudrich
- Institute for General Kinesiology and Exercise Science, Faculty of Sports Science, University of Leipzig, Leipzig, Germany.,Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany
| | - Carmen Vidaurre
- Department of Statistics, Informatics and Mathematics, Public University of Navarre, Pamplona, Spain.,Machine Learning Group, Faculty of EE and Computer Science, TU Berlin, Berlin, Germany
| | - Dennis Maudrich
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany
| | - Arno Villringer
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany.,MindBrainBody Institute at Berlin School of Mind and Brain, Charité-Universitätsmedizin Berlin and Humboldt-Universität zu Berlin, Germany.,Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany
| | - Patrick Ragert
- Institute for General Kinesiology and Exercise Science, Faculty of Sports Science, University of Leipzig, Leipzig, Germany.,Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany
| | - Vadim V Nikulin
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neurology, Leipzig, Germany.,Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow, Russian Federation.,Neurophysics Group, Department of Neurology, Charité-University Medicine Berlin, Campus Benjamin Franklin, Berlin, Germany
| |
Collapse
|
12
|
Usler ER, Wei X, Simione M, Richburg B, Stipancic KL, Green JR. Modulation of Intermuscular Beta Coherence in Different Rhythmic Mandibular Behaviors. Front Hum Neurosci 2020; 14:302. [PMID: 32848676 PMCID: PMC7406789 DOI: 10.3389/fnhum.2020.00302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 07/08/2020] [Indexed: 11/23/2022] Open
Abstract
Introduction Jaw movement during chewing and speech is facilitated by neural activation patterns for opening and closing movements of the mandible. This study investigated anatomic- and task-dependent differences in intermuscular coherence (IMC) and their association with the parameters of jaw muscle activity using surface electromyography (sEMG). Methods We recorded sEMG activation from bilateral and ipsilateral jaw-closing muscle pairs during non-nutritive and nutritive chewing, and during a syllable repetition task. IMC and cross-correlational analyses between bilateral and ipsilateral muscle pairs were performed. Results Intermuscular coherence in the beta band was statistically significant between agonist jaw-closing muscle pairs, with beta IMC weaker for rapid syllable repetition compared to chewing tasks. Cross-correlational analysis of muscle co-activation, as well as sEMG burst amplitude, was positively associated with beta IMC strength. Discussion Beta IMC was influenced heavily by task-dependent behavioral goals and physiologic demands, which was interpreted as evidence of shared neural drive among jaw-closing muscles.
Collapse
Affiliation(s)
- Evan R. Usler
- Department of Communication Sciences and Disorders, College of Health Sciences, University of Delaware, Newark, DE, United States
- *Correspondence: Evan R. Usler,
| | - Xiaomei Wei
- Department of Rehabilitation Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Meg Simione
- Department of Pediatrics, Massachusetts General Hospital, Boston, MA, United States
| | - Brian Richburg
- Speech and Feeding Disorders Laboratory, MGH Institute of Health Professions, Boston, MA, United States
| | - Kaila L. Stipancic
- Speech and Feeding Disorders Laboratory, MGH Institute of Health Professions, Boston, MA, United States
| | - Jordan R. Green
- Speech and Feeding Disorders Laboratory, MGH Institute of Health Professions, Boston, MA, United States
| |
Collapse
|
13
|
Kerkman JN, Bekius A, Boonstra TW, Daffertshofer A, Dominici N. Muscle Synergies and Coherence Networks Reflect Different Modes of Coordination During Walking. Front Physiol 2020; 11:751. [PMID: 32792967 PMCID: PMC7394052 DOI: 10.3389/fphys.2020.00751] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/10/2020] [Indexed: 11/13/2022] Open
Abstract
When walking speed is increased, the frequency ratio between the arm and leg swing switches spontaneously from 2:1 to 1:1. We examined whether these switches are accompanied by changes in functional connectivity between multiple muscles. Subjects walked on a treadmill with their arms swinging along their body while kinematics and surface electromyography (EMG) of 26 bilateral muscles across the body were recorded. Walking speed was varied from very slow to normal. We decomposed EMG envelopes and intermuscular coherence spectra using non-negative matrix factorization (NMF), and the resulting modes were combined into multiplex networks and analyzed for their community structure. We found five relevant muscle synergies that significantly differed in activation patterns between 1:1 and 2:1 arm-leg coordination and the transition period between them. The corresponding multiplex network contained a single module indicating pronounced muscle co-activation patterns across the whole body during a gait cycle. NMF of the coherence spectra distinguished three EMG frequency bands: 4-8, 8-22, and 22-60 Hz. The community structure of the multiplex network revealed four modules, which clustered functional and anatomical linked muscles across modes of coordination. Intermuscular coherence at 4-22 Hz between upper and lower body and within the legs was particularly pronounced for 1:1 arm-leg coordination and was diminished when switching between modes of coordination. These findings suggest that the stability of arm-leg coordination is associated with modulations in long-distant neuromuscular connectivity.
Collapse
Affiliation(s)
- Jennifer N. Kerkman
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences & Institute for Brain and Behavior Amsterdam, Vrije Universiteit, Amsterdam, Netherlands
| | - Annike Bekius
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences & Institute for Brain and Behavior Amsterdam, Vrije Universiteit, Amsterdam, Netherlands
| | - Tjeerd W. Boonstra
- Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
- Neuroscience Research Australia, Randwick, NSW, Australia
| | - Andreas Daffertshofer
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences & Institute for Brain and Behavior Amsterdam, Vrije Universiteit, Amsterdam, Netherlands
| | - Nadia Dominici
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences & Institute for Brain and Behavior Amsterdam, Vrije Universiteit, Amsterdam, Netherlands
| |
Collapse
|
14
|
Degani AM, Leonard CT, Danna-Dos-Santos A. The effects of aging on the distribution and strength of correlated neural inputs to postural muscles during unperturbed bipedal stance. Exp Brain Res 2020; 238:1537-1553. [PMID: 32451586 DOI: 10.1007/s00221-020-05837-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/15/2020] [Indexed: 11/24/2022]
Abstract
The present study investigated the effects of aging on the distribution of common descending neural drives to main postural muscles acting on the ankle, knee, hip, and lower trunk. The presence, distribution, and strength of these drives were assessed using intermuscular coherence estimations at a low-frequency band (0-55 Hz). Ten healthy older adults (68.7 ± 3.5 years) with no recent history of falls and ten healthy younger adults (26.8 ± 2.7 years) performed bipedal stances with eyes either opened or closed. Electromyographic (EMG) signals of six postural muscles were recorded. Estimations of intermuscular coherence were obtained from fifteen muscle pairs and four muscle groups. In general, single-pair and pooled coherence analyzes revealed significant levels of signal synchronization within 1-10 Hz. Significant common drives to anterior, posterior, and antagonist muscle groups were observed for both cohorts of participants. However, older participants showed significantly stronger EMG-EMG synchronization in the frequency domain compared to younger participants. It seems that age-related sarcopenia, visual-vestibular-proprioceptive decline, cortical activation increase, presynaptic inhibition modulation decrease, and co-contraction increase had a major impact on strengthening the common drives to the aforementioned muscle groups. Differently from young adults, the absence of visual inputs did not reduce the magnitude of signal synchronization in older adults. These results suggest that the aging central nervous system seems to organize similar arrangements of common drives to postural antagonist muscles at different joints, and to postural muscles pushing the body either forward or backward when visual information is not available.
Collapse
Affiliation(s)
- Adriana M Degani
- Department of Physical Therapy, Western Michigan University, 1903 West Michigan Ave, Kalamazoo, MI, 49008-5383, USA. .,Unified Clinics, Western Michigan University, 1000 Oakland Dr, Kalamazoo, MI, 49008-5383, USA.
| | - Charles T Leonard
- School of Physical Therapy and Rehabilitation Science, University of Montana, Missoula, MT, 59812-4680, USA
| | - Alessander Danna-Dos-Santos
- Department of Physical Therapy, Western Michigan University, 1903 West Michigan Ave, Kalamazoo, MI, 49008-5383, USA
| |
Collapse
|
15
|
Corticomuscular control of walking in older people and people with Parkinson's disease. Sci Rep 2020; 10:2980. [PMID: 32076045 PMCID: PMC7031238 DOI: 10.1038/s41598-020-59810-w] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 01/30/2020] [Indexed: 12/29/2022] Open
Abstract
Changes in human gait resulting from ageing or neurodegenerative diseases are multifactorial. Here we assess the effects of age and Parkinson’s disease (PD) on corticospinal activity recorded during treadmill and overground walking. Electroencephalography (EEG) from 10 electrodes and electromyography (EMG) from bilateral tibialis anterior muscles were acquired from 22 healthy young, 24 healthy older and 20 adults with PD. Event-related power, corticomuscular coherence (CMC) and inter-trial coherence were assessed for EEG from bilateral sensorimotor cortices and EMG during the double-support phase of the gait cycle. CMC and EMG power at low beta frequencies (13–21 Hz) was significantly decreased in older and PD participants compared to young people, but there was no difference between older and PD groups. Older and PD participants spent shorter time in the swing phase than young individuals. These findings indicate age-related changes in the temporal coordination of gait. The decrease in low-beta CMC suggests reduced cortical input to spinal motor neurons in older people during the double-support phase. We also observed multiple changes in electrophysiological measures at low-gamma frequencies during treadmill compared to overground walking, indicating task-dependent differences in corticospinal locomotor control. These findings may be affected by artefacts and should be interpreted with caution.
Collapse
|
16
|
Palacios-García I, Parada FJ. Measuring the Brain-Gut Axis in Psychological Sciences: A Necessary Challenge. Front Integr Neurosci 2020; 13:73. [PMID: 31998086 PMCID: PMC6962305 DOI: 10.3389/fnint.2019.00073] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/09/2019] [Indexed: 12/18/2022] Open
Affiliation(s)
- Ismael Palacios-García
- Laboratorio de Psicofisiología, Escuela de Psicología, Pontificia Universidad Católica de Chile, Santiago, Chile
- Laboratorio de Neurociencia Cognitiva y Social, Facultad de Psicología, Universidad Diego Portales, Santiago, Chile
| | - Francisco J. Parada
- Laboratorio de Neurociencia Cognitiva y Social, Facultad de Psicología, Universidad Diego Portales, Santiago, Chile
| |
Collapse
|
17
|
Hu G, Yang W, Chen X, Qi W, Li X, Du Y, Xie P. Estimation of Time-Varying Coherence Amongst Synergistic Muscles During Wrist Movements. Front Neurosci 2018; 12:537. [PMID: 30131672 PMCID: PMC6090894 DOI: 10.3389/fnins.2018.00537] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 07/17/2018] [Indexed: 12/11/2022] Open
Abstract
The central nervous system (CNS) controls the limb movement by modulating multiple skeletal muscles with synergistic modules and neural oscillations with different frequencies between the activated muscles. Several researchers have found intermuscular coherence existing within the synergistic muscle pairs, and pointed out that the intermuscular synchronization existed when functional forces were generated. However, few studies involved the time-varying characteristics of the intermuscular coherence in each synergy module though all activated muscles keep in a dynamic and varying process. Therefore, this study aims to explore the time-varying coherence amongst synergistic muscles during movements based on the combination of the non-negative matrix factorization (NMF) method and the time-frequency coherence (TFC) method. We applied these methods into the electromyogram (EMG) signals recorded from eight muscles involved in the sequence of the wrist movements [wrist flexion (WF), wrist flexion transmission to wrist extension (MC) and wrist extension (WE)] in 12 healthy people. The results showed three synergistic flexor pairs (FCR-PL, FCR-FDS, and PL-FDS) in the WF stage and three extensor pairs (ECU-ECR, ECU-B, and ECR-B) in both MC and WE stages. Further analysis showed intermuscular coherence between each pairwise synergistic muscles. The intermuscular coherence between the flexor muscle pairs was mainly observed in the beta band (15-35 Hz) during the WF stage, and that amongst the extensor muscle pairs was also observed in the beta band during the WE stage. However, the intermuscular coherence between the extensor muscle pairs mainly on gamma band during the MC stage. Additionally, compared to the flexor muscle pairs, the intermuscular coherence of the extensor muscle pairs were lower in the WF stage, and higher in both MC and WE stages. These results demonstrated the time-varying mechanisms of the synergistic modulation and synchronous oscillation in motor-control system. This study contributes to expanded researches for motor control.
Collapse
Affiliation(s)
- Guiting Hu
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Wenjuan Yang
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Xiaoling Chen
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Wenjing Qi
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Xinxin Li
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Yihao Du
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| | - Ping Xie
- Key Lab of Measurement Technology and Instrumentation of Hebei Province, Institute of Electric Engineering, Yanshan University, Qinhuangdao, China
| |
Collapse
|
18
|
Aguiar SA, Baker SN, Gant K, Bohorquez J, Thomas CK. Spasms after spinal cord injury show low-frequency intermuscular coherence. J Neurophysiol 2018; 120:1765-1771. [PMID: 30067124 PMCID: PMC6230810 DOI: 10.1152/jn.00112.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intermuscular coherence allows the investigation of common input to muscle groups. Although beta-band (15–30 Hz) intermuscular coherence is well understood as originating from the cortex, the source of intermuscular coherence at lower frequencies is still unclear. We used a wearable device that recorded electromyographic (EMG) signals during a 24-h period in four lower limb muscles of seven spinal cord injury patients (American Spinal Cord Injury Association impairment scale: A, 6 subjects; B, 1 subject) while they went about their normal daily life activities. We detected natural spasms occurring during these long-lasting recordings and calculated intermuscular coherence between all six possible combinations of muscle pairs. There was significant intermuscular coherence at low frequencies, between 2 and 13 Hz. The most likely source for this was the spinal cord and its peripheral feedback loops, because the spinal lesions in these patients had interrupted connections to supraspinal structures. This is the first report to demonstrate that the spinal cord is capable of producing low-frequency intermuscular coherence with severely reduced or abolished descending drive. NEW & NOTEWORTHY This is the first report to demonstrate that intermuscular coherence between lower limb muscles at low frequencies can be produced by the spinal cord with severely reduced or abolished descending drive.
Collapse
Affiliation(s)
- Stefane A Aguiar
- Institute of Neuroscience, Newcastle University , Newcastle Upon Tyne , United Kingdom
| | - Stuart N Baker
- Institute of Neuroscience, Newcastle University , Newcastle Upon Tyne , United Kingdom
| | - Katie Gant
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine , Miami, Florida
| | - Jorge Bohorquez
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine , Miami, Florida.,Department of Biomedical Engineering, University of Miami Miller School of Medicine , Miami, Florida
| | - Christine K Thomas
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine , Miami, Florida.,Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida.,Department of Physiology and Biophysics, University of Miami Miller School of Medicine , Miami, Florida
| |
Collapse
|
19
|
Roeder L, Boonstra TW, Smith SS, Kerr GK. Dynamics of corticospinal motor control during overground and treadmill walking in humans. J Neurophysiol 2018; 120:1017-1031. [PMID: 29847229 DOI: 10.1152/jn.00613.2017] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increasing evidence suggests cortical involvement in the control of human gait. However, the nature of corticospinal interactions remains poorly understood. We performed time-frequency analysis of electrophysiological activity acquired during treadmill and overground walking in 22 healthy, young adults. Participants walked at their preferred speed (4.2, SD 0.4 km/h), which was matched across both gait conditions. Event-related power, corticomuscular coherence (CMC), and intertrial coherence (ITC) were assessed for EEG from bilateral sensorimotor cortices and EMG from the bilateral tibialis anterior (TA) muscles. Cortical power, CMC, and ITC at theta, alpha, beta, and gamma frequencies (4-45 Hz) increased during the double support phase of the gait cycle for both overground and treadmill walking. High beta (21-30 Hz) CMC and ITC of EMG was significantly increased during overground compared with treadmill walking, as well as EEG power in theta band (4-7 Hz). The phase spectra revealed positive time lags at alpha, beta, and gamma frequencies, indicating that the EEG response preceded the EMG response. The parallel increases in power, CMC, and ITC during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. The evoked responses are not consistent with the idea of synchronization of ongoing corticospinal oscillations but instead suggest coordinated cortical and spinal inputs during the double support phase. Frequency-band dependent differences in power, CMC, and ITC between overground and treadmill walking suggest differing neural control for the two gait modalities, emphasizing the task-dependent nature of neural processes during human walking. NEW & NOTEWORTHY We investigated cortical and spinal activity during overground and treadmill walking in healthy adults. Parallel increases in power, corticomuscular coherence, and intertrial coherence during double support suggest evoked responses at spinal and cortical populations rather than a modulation of ongoing corticospinal oscillatory interactions. These findings identify neurophysiological mechanisms that are important for understanding cortical control of human gait in health and disease.
Collapse
Affiliation(s)
- Luisa Roeder
- Movement Neuroscience Group, Institute of Health and Biomedical Innovation, Queensland University of Technology , Brisbane , Australia.,School of Exercise and Nutrition Sciences, Queensland University of Technology , Brisbane , Australia
| | - Tjeerd W Boonstra
- Black Dog Institute, University of New South Wales , Sydney , Australia.,Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, Brisbane , Australia
| | - Simon S Smith
- Institute of Social Science Research, University of Queensland , Brisbane , Australia
| | - Graham K Kerr
- Movement Neuroscience Group, Institute of Health and Biomedical Innovation, Queensland University of Technology , Brisbane , Australia.,School of Exercise and Nutrition Sciences, Queensland University of Technology , Brisbane , Australia
| |
Collapse
|
20
|
Nojima I, Watanabe T, Saito K, Tanabe S, Kanazawa H. Modulation of EMG-EMG Coherence in a Choice Stepping Task. Front Hum Neurosci 2018; 12:50. [PMID: 29487515 PMCID: PMC5816746 DOI: 10.3389/fnhum.2018.00050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/30/2018] [Indexed: 12/11/2022] Open
Abstract
The voluntary step execution task is a popular measure for identifying fall risks among elderly individuals in the community setting because most falls have been reported to occur during movement. However, the neurophysiological functions during this movement are not entirely understood. Here, we used electromyography (EMG) to explore the relationship between EMG-EMG coherence, which reflects common oscillatory drive to motoneurons, and motor performance associated with stepping tasks: simple reaction time (SRT) and choice reaction time (CRT) tasks. Ten healthy elderly adults participated in the study. Participants took a single step forward in response to a visual imperative stimulus. EMG-EMG coherence was analyzed for 1000 ms before the presentation of the stimulus (stationary standing position) from proximal and distal tibialis anterior (TA) and soleus (SOL) muscles. The main result showed that all paired EMG-EMG coherences in the alpha and beta frequency bands were greater in the SRT than the CRT task. This finding suggests that the common oscillatory drive to the motoneurons during the SRT task occurred prior to taking a step, whereas the lower value of corticospinal activity during the CRT task prior to taking a step may indicate an involvement of inhibitory activity, which is consistent with observations from our previous study (Watanabe et al., 2016). Furthermore, the beta band coherence in intramuscular TA tended to positively correlate with the number of performance errors that are associated with fall risks in the CRT task, suggesting that a reduction in the inhibitory activity may result in a decrease of stepping performance. These findings could advance the understanding of the neurophysiological features of postural adjustments in elderly individuals.
Collapse
Affiliation(s)
- Ippei Nojima
- Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tatsunori Watanabe
- Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kotaro Saito
- Department of Physical Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shigeo Tanabe
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Hoshinori Kanazawa
- Japan Society for the Promotion of Science, Tokyo, Japan.,Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
21
|
The use of intermuscular coherence analysis as a novel approach to detect age-related changes on postural muscle synergy. Neurosci Lett 2017; 656:108-113. [PMID: 28732761 DOI: 10.1016/j.neulet.2017.07.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/11/2017] [Accepted: 07/17/2017] [Indexed: 11/22/2022]
Abstract
The overall goal of this study was to investigate potential adaptations brought about by the natural processes of aging on the coordination of postural muscles. Considering the progressive and non-homogeneous deterioration of sensorimotor and neuromuscular systems as the individual grows older, it was hypothesized that aging is associated with a reorganization of synergistic mechanisms controlling postural muscles. Therefore, the presence, distribution, and strength of correlated neural inputs to three posterior postural muscles were measured by intermuscular coherence estimations at a low frequency band (0-55Hz). Nine healthy young adults and thirteen healthy older adults performed ten trials of a perturbed task: bipedal stance while holding a five kg load for fifteen seconds. Estimates of intermuscular coherence for each pair of electromyographic signals (soleus and biceps femoris, soleus and erector spinae, and biceps femoris and erector spinae) were computed. Results revealed significantly stronger levels of synchronization of posterior muscles within 0-10Hz in seniors compared to young adults. In addition, seniors presented similar spectra of intermuscular coherence within 0-55Hz for all three muscle pairs analyzed. These findings provide valuable information regarding compensatory mechanisms adopted by older adults to control balance. The age-related reorganization of neural drive controlling posterior postural muscles revealing a stronger synchronization within 0-10Hz might be related to the faster body sway and muscle co-activation patterns usually observed in this population. Finally, this study supports the use of Intermuscular Coherence Analysis as a sensitive method to detect age-related changes in multi-muscle control.
Collapse
|
22
|
Effect of training status on beta-range corticomuscular coherence in agonist vs. antagonist muscles during isometric knee contractions. Exp Brain Res 2017; 235:3023-3031. [DOI: 10.1007/s00221-017-5035-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 07/15/2017] [Indexed: 10/19/2022]
|
23
|
Laine CM, Valero-Cuevas FJ. Intermuscular coherence reflects functional coordination. J Neurophysiol 2017; 118:1775-1783. [PMID: 28659460 DOI: 10.1152/jn.00204.2017] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
Coherence analysis has the ability to identify the presence of common descending drive shared by motor unit pools and reveals its spectral properties. However, the link between spectral properties of shared neural drive and functional interactions among muscles remains unclear. We assessed shared neural drive between muscles of the thumb and index finger while participants executed two mechanically distinct precision pinch tasks, each requiring distinct functional coordination among muscles. We found that shared neural drive was systematically reduced or enhanced at specific frequencies of interest (~10 and ~40 Hz). While amplitude correlations between surface EMG signals also exhibited changes across tasks, only their coherence has strong physiological underpinnings indicative of neural binding. Our results support the use of intermuscular coherence as a tool to detect when coactivated muscles are members of a functional group or synergy of neural origin. Furthermore, our results demonstrate the advantages of considering neural binding at 10, ~20, and >30 Hz, as indicators of task-dependent neural coordination strategies.NEW & NOTEWORTHY It is often unclear whether correlated activity among muscles reflects their neural binding or simply reflects the constraints defining the task. Using the fact that high-frequency coherence between EMG signals (>6 Hz) is thought to reflect shared neural drive, we demonstrate that coherence analysis can reveal the neural origin of distinct muscle coordination patterns required by different tasks.
Collapse
Affiliation(s)
- Christopher M Laine
- Brain-Body Dynamics Laboratory, Department of Biomedical Engineering, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California
| | - Francisco J Valero-Cuevas
- Brain-Body Dynamics Laboratory, Department of Biomedical Engineering, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California
| |
Collapse
|
24
|
Frère J. Spectral properties of multiple myoelectric signals: New insights into the neural origin of muscle synergies. Neuroscience 2017; 355:22-35. [PMID: 28483469 DOI: 10.1016/j.neuroscience.2017.04.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 04/07/2017] [Accepted: 04/26/2017] [Indexed: 01/24/2023]
Abstract
It is still unclear if muscle synergies reflect neural strategies or mirror the underlying mechanical constraints. Therefore, this study aimed to verify the consistency of muscle groupings between the synergies based on the linear envelope (LE) of muscle activities and those incorporating the time-frequency (TF) features of the electromyographic (EMG) signals. Twelve healthy participants performed six 20-m walking trials at a comfort and fast self-selected speed, while the activity of eleven lower limb muscles was recorded by means of surface EMG. Wavelet-transformed EMG was used to obtain the TF pattern and muscle synergies were extracted by non-negative matrix factorization. When five muscle synergies were extracted, both methods defined similar muscle groupings whatever the walking speed. When accounting the reconstruction level of the initial dataset, a new TF synergy emerged. This new synergy dissociated the activity of the rectus femoris from those of the vastii muscles (synergy #1) and from the one of the tensor fascia latae (synergy #5). Overall, extracting TF muscle synergies supports the neural origin of muscle synergies and provides an opportunity to distinguish between prescriptive and descriptive muscle synergies.
Collapse
Affiliation(s)
- Julien Frère
- University of Lorraine, Laboratory "Development, Adaption and Disability" (EA 3450), Faculty of Sports Sciences, 30 rue du Jardin Botanique, CS 30156, F-54603 Villers-lès-Nancy, France.
| |
Collapse
|
25
|
Reyes A, Laine CM, Kutch JJ, Valero-Cuevas FJ. Beta Band Corticomuscular Drive Reflects Muscle Coordination Strategies. Front Comput Neurosci 2017; 11:17. [PMID: 28420975 PMCID: PMC5378725 DOI: 10.3389/fncom.2017.00017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/10/2017] [Indexed: 12/11/2022] Open
Abstract
During force production, hand muscle activity is known to be coherent with activity in primary motor cortex, specifically in the beta-band (15–30 Hz) frequency range. It is not clear, however, if this coherence reflects the control strategy selected by the nervous system for a given task, or if it instead reflects an intrinsic property of cortico-spinal communication. Here, we measured corticomuscular and intermuscular coherence between muscles of index finger and thumb while a two-finger pinch grip of identical net force was applied to objects which were either stable (allowing synergistic activation of finger muscles) or unstable (requiring individuated finger control). We found that beta-band corticomuscular coherence with the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles, as well as their beta-band coherence with each other, was significantly reduced when individuated control of the thumb and index finger was required. We interpret these findings to show that beta-band coherence is reflective of a synergistic control strategy in which the cortex binds task-related motor neurons into functional units.
Collapse
Affiliation(s)
- Alexander Reyes
- Brain-Body Dynamics Lab, Department of Biomedical Engineering, University of Southern CaliforniaLos Angeles, CA, USA
| | - Christopher M Laine
- Brain-Body Dynamics Lab, Department of Biomedical Engineering, University of Southern CaliforniaLos Angeles, CA, USA
| | - Jason J Kutch
- Applied Mathematical Physiology Lab, Division of Biokinesiology and Physical Therapy, University of Southern CaliforniaLos Angeles, CA, USA
| | - Francisco J Valero-Cuevas
- Brain-Body Dynamics Lab, Department of Biomedical Engineering, University of Southern CaliforniaLos Angeles, CA, USA
| |
Collapse
|
26
|
de Vries IEJ, Daffertshofer A, Stegeman DF, Boonstra TW. Functional connectivity in the neuromuscular system underlying bimanual coordination. J Neurophysiol 2016; 116:2576-2585. [PMID: 27628205 DOI: 10.1152/jn.00460.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/09/2016] [Indexed: 11/22/2022] Open
Abstract
Neural synchrony has been suggested as a mechanism for integrating distributed sensorimotor systems involved in coordinated movement. To test the role of corticomuscular and intermuscular coherence in bimanual coordination, we experimentally manipulated the degree of coordination between hand muscles by varying the sensitivity of the visual feedback to differences in bilateral force. In 16 healthy participants, cortical activity was measured using EEG and muscle activity of the flexor pollicis brevis of both hands using high-density electromyography (HDsEMG). Using the uncontrolled manifold framework, coordination between bilateral forces was quantified by the synergy index RV in the time and frequency domain. Functional connectivity was assessed using corticomuscular coherence between muscle activity and cortical source activity and intermuscular coherence between bilateral EMG activity. The synergy index increased in the high coordination condition. RV was higher in the high coordination condition in frequencies between 0 and 0.5 Hz; for the 0.5- to 2-Hz frequency band, this pattern was inverted. Corticomuscular coherence in the beta band (16-30 Hz) was maximal in the contralateral motor cortex and was reduced in the high coordination condition. In contrast, intermuscular coherence was observed at 5-12 Hz and increased with bimanual coordination. Within-subject comparisons revealed a negative correlation between RV and corticomuscular coherence and a positive correlation between RV and intermuscular coherence. Our findings suggest two distinct neural pathways: 1) corticomuscular coherence reflects direct corticospinal projections involved in controlling individual muscles; and 2) intermuscular coherence reflects diverging pathways involved in the coordination of multiple muscles.
Collapse
Affiliation(s)
- Ingmar E J de Vries
- Faculty of Behavioural and Movement Sciences, VU University, Amsterdam, The Netherlands
| | - Andreas Daffertshofer
- Faculty of Behavioural and Movement Sciences, VU University, Amsterdam, The Netherlands
| | - Dick F Stegeman
- Faculty of Behavioural and Movement Sciences, VU University, Amsterdam, The Netherlands.,Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen, The Netherlands
| | - Tjeerd W Boonstra
- Faculty of Behavioural and Movement Sciences, VU University, Amsterdam, The Netherlands; .,Black Dog Institute, University of New South Wales, Sydney, Australia; and.,Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| |
Collapse
|
27
|
Boonstra TW, Danna-Dos-Santos A, Xie HB, Roerdink M, Stins JF, Breakspear M. Muscle networks: Connectivity analysis of EMG activity during postural control. Sci Rep 2015; 5:17830. [PMID: 26634293 PMCID: PMC4669476 DOI: 10.1038/srep17830] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 11/06/2015] [Indexed: 01/08/2023] Open
Abstract
Understanding the mechanisms that reduce the many degrees of freedom in the musculoskeletal system remains an outstanding challenge. Muscle synergies reduce the dimensionality and hence simplify the control problem. How this is achieved is not yet known. Here we use network theory to assess the coordination between multiple muscles and to elucidate the neural implementation of muscle synergies. We performed connectivity analysis of surface EMG from ten leg muscles to extract the muscle networks while human participants were standing upright in four different conditions. We observed widespread connectivity between muscles at multiple distinct frequency bands. The network topology differed significantly between frequencies and between conditions. These findings demonstrate how muscle networks can be used to investigate the neural circuitry of motor coordination. The presence of disparate muscle networks across frequencies suggests that the neuromuscular system is organized into a multiplex network allowing for parallel and hierarchical control structures.
Collapse
Affiliation(s)
- Tjeerd W Boonstra
- MOVE Research Institute Amsterdam, VU University, Amsterdam, The Netherlands.,Black Dog Institute, University of New South Wales, Sydney, Australia
| | | | - Hong-Bo Xie
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, Australia
| | - Melvyn Roerdink
- MOVE Research Institute Amsterdam, VU University, Amsterdam, The Netherlands
| | - John F Stins
- MOVE Research Institute Amsterdam, VU University, Amsterdam, The Netherlands
| | - Michael Breakspear
- Black Dog Institute, University of New South Wales, Sydney, Australia.,QIMR Berghofer Medical Research Institute, Brisbane, Australia
| |
Collapse
|
28
|
Task-Dependent Intermuscular Motor Unit Synchronization between Medial and Lateral Vastii Muscles during Dynamic and Isometric Squats. PLoS One 2015; 10:e0142048. [PMID: 26529604 PMCID: PMC4631473 DOI: 10.1371/journal.pone.0142048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/17/2015] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Motor unit activity is coordinated between many synergistic muscle pairs but the functional role of this coordination for the motor output is unclear. The purpose of this study was to investigate the short-term modality of coordinated motor unit activity-the synchronized discharge of individual motor units across muscles within time intervals of 5ms-for the Vastus Medialis (VM) and Lateralis (VL). Furthermore, we studied the task-dependency of intermuscular motor unit synchronization between VM and VL during static and dynamic squatting tasks to provide insight into its functional role. METHODS Sixteen healthy male and female participants completed four tasks: Bipedal squats, single-leg squats, an isometric squat, and single-leg balance. Monopolar surface electromyography (EMG) was used to record motor unit activity of VM and VL. For each task, intermuscular motor unit synchronization was determined using a coherence analysis between the raw EMG signals of VM and VL and compared to a reference coherence calculated from two desynchronized EMG signals. The time shift between VM and VL EMG signals was estimated according to the slope of the coherence phase angle spectrum. RESULTS For all tasks, except for singe-leg balance, coherence between 15-80Hz significantly exceeded the reference. The corresponding time shift between VM and VL was estimated as 4ms. Coherence between 30-60Hz was highest for the bipedal squat, followed by the single-leg squat and the isometric squat. CONCLUSION There is substantial short-term motor unit synchronization between VM and VL. Intermuscular motor unit synchronization is enhanced for contractions during dynamic activities, possibly to facilitate a more accurate control of the joint torque, and reduced during single-leg tasks that require balance control and thus, a more independent muscle function. It is proposed that the central nervous system scales the degree of intermuscular motor unit synchronization according to the requirements of the movement task at hand.
Collapse
|
29
|
Kline JC, De Luca CJ. Synchronization of motor unit firings: an epiphenomenon of firing rate characteristics not common inputs. J Neurophysiol 2015; 115:178-92. [PMID: 26490288 DOI: 10.1152/jn.00452.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 10/16/2015] [Indexed: 01/21/2023] Open
Abstract
Synchronous motor unit firing instances have been attributed to anatomical inputs shared by motoneurons. Yet, there is a lack of empirical evidence confirming the notion that common inputs elicit synchronization under voluntary conditions. We tested this notion by measuring synchronization between motor unit action potential trains (MUAPTs) as their firing rates progressed within a contraction from a relatively low force level to a higher one. On average, the degree of synchronization decreased as the force increased. The common input notion provides no empirically supported explanation for the observed synchronization behavior. Therefore, we investigated a more probable explanation for synchronization. Our data set of 17,546 paired MUAPTs revealed that the degree of synchronization varies as a function of two characteristics of the motor unit firing rate: the similarity and the slope as a function of force. Both are measures of the excitation of the motoneurons. As the force generated by the muscle increases, the firing rate slope decreases, and the synchronization correspondingly decreases. Different muscles have motor units with different firing rate characteristics and display different amounts of synchronization. Although this association is not proof of causality, it consistently explains our observations and strongly suggests further investigation. So viewed, synchronization is likely an epiphenomenon, subject to countless unknown neural interactions. As such, synchronous firing instances may not be the product of a specific design and may not serve a specific physiological purpose. Our explanation for synchronization has the advantage of being supported by empirical evidence, whereas the common input does not.
Collapse
Affiliation(s)
- Joshua C Kline
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts; and Delsys Incorporated, Natick, Massachusetts
| | - Carlo J De Luca
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts; and Delsys Incorporated, Natick, Massachusetts
| |
Collapse
|
30
|
De Marchis C, Severini G, Castronovo AM, Schmid M, Conforto S. Intermuscular coherence contributions in synergistic muscles during pedaling. Exp Brain Res 2015; 233:1907-19. [DOI: 10.1007/s00221-015-4262-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/18/2015] [Indexed: 01/01/2023]
|
31
|
Danna-Dos-Santos A, Degani AM, Boonstra TW, Mochizuki L, Harney AM, Schmeckpeper MM, Tabor LC, Leonard CT. The influence of visual information on multi-muscle control during quiet stance: a spectral analysis approach. Exp Brain Res 2014; 233:657-69. [DOI: 10.1007/s00221-014-4145-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 11/07/2014] [Indexed: 10/24/2022]
|
32
|
Steeg CVD, Daffertshofer A, Stegeman DF, Boonstra TW. High-density surface electromyography improves the identification of oscillatory synaptic inputs to motoneurons. J Appl Physiol (1985) 2014; 116:1263-71. [PMID: 24651985 DOI: 10.1152/japplphysiol.01092.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many studies have addressed corticomuscular coherence (CMC), but broad applications are limited by low coherence values and the variability across subjects and recordings. Here, we investigated how the use of high-density surface electromyography (HDsEMG) can improve the detection of CMC. Sixteen healthy subjects performed isometric contractions at six low-force levels using a pinch-grip, while HDsEMG of the adductor pollicis transversus and flexor and abductor pollicis brevis and whole-head magnetoencephalography were recorded. Different configurations were constructed from the HDsEMG grid, such as a bipolar and Laplacian montage, as well as a montage based on principal component analysis (PCA). CMC was estimated for each configuration, and the strength of coherence was compared across configurations. As expected, performance of the precision-grip task resulted in significant CMC in the β-frequency band (16-26 Hz). Compared with a bipolar EMG montage, all multichannel configurations obtained from the HDsEMG grid revealed a significant increase in CMC. The configuration, based on PCA, showed the largest (37%) increase. HDsEMG did not reduce the between-subject variability; rather, many configurations showed an increased coefficient of variation. Increased CMC presumably reflects the ability of HDsEMG to counteract inherent EMG signal factors-such as amplitude cancellation-which impact the detection of oscillatory inputs. In contrast, the between-subject variability of CMC most likely has a cortical origin.
Collapse
Affiliation(s)
- Chiel van de Steeg
- MOVE Research Institute, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | | | - Dick F Stegeman
- MOVE Research Institute, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; Donders Institute for Brain, Cognition and Behavior, Radboud University, Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Tjeerd W Boonstra
- MOVE Research Institute, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands; School of Psychiatry, University of New South Wales, Sydney, Australia; and Black Dog Institute, Sydney, Australia
| |
Collapse
|
33
|
Boonstra TW. The potential of corticomuscular and intermuscular coherence for research on human motor control. Front Hum Neurosci 2013; 7:855. [PMID: 24339813 PMCID: PMC3857603 DOI: 10.3389/fnhum.2013.00855] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 11/22/2013] [Indexed: 11/27/2022] Open
Affiliation(s)
- Tjeerd W Boonstra
- School of Psychiatry, University of New South Wales Sydney, NSW, Australia ; Black Dog Institute Sydney, NSW, Australia ; MOVE Research Institute, VU University Amsterdam, Netherlands
| |
Collapse
|
34
|
Multi-muscle control during bipedal stance: an EMG–EMG analysis approach. Exp Brain Res 2013; 232:75-87. [DOI: 10.1007/s00221-013-3721-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 09/20/2013] [Indexed: 10/26/2022]
|
35
|
Birznieks I, Boonstra TW, Macefield VG. Modulation of human muscle spindle discharge by arterial pulsations--functional effects and consequences. PLoS One 2012; 7:e35091. [PMID: 22529975 PMCID: PMC3328488 DOI: 10.1371/journal.pone.0035091] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 03/13/2012] [Indexed: 11/18/2022] Open
Abstract
Arterial pulsations are known to modulate muscle spindle firing; however, the physiological significance of such synchronised modulation has not been investigated. Unitary recordings were made from 75 human muscle spindle afferents innervating the pretibial muscles. The modulation of muscle spindle discharge by arterial pulsations was evaluated by R-wave triggered averaging and power spectral analysis. We describe various effects arterial pulsations may have on muscle spindle afferent discharge. Afferents could be "driven" by arterial pulsations, e.g., showing no other spontaneous activity than spikes generated with cardiac rhythmicity. Among afferents showing ongoing discharge that was not primarily related to cardiac rhythmicity we illustrate several mechanisms by which individual spikes may become phase-locked. However, in the majority of afferents the discharge rate was modulated by the pulse wave without spikes being phase locked. Then we assessed whether these influences changed in two physiological conditions in which a sustained increase in muscle sympathetic nerve activity was observed without activation of fusimotor neurones: a maximal inspiratory breath-hold, which causes a fall in systolic pressure, and acute muscle pain, which causes an increase in systolic pressure. The majority of primary muscle spindle afferents displayed pulse-wave modulation, but neither apnoea nor pain had any significant effect on the strength of this modulation, suggesting that the physiological noise injected by the arterial pulsations is robust and relatively insensitive to fluctuations in blood pressure. Within the afferent population there was a similar number of muscle spindles that were inhibited and that were excited by the arterial pulse wave, indicating that after signal integration at the population level, arterial pulsations of opposite polarity would cancel each other out. We speculate that with close-to-threshold stimuli the arterial pulsations may serve as an endogenous noise source that may synchronise the sporadic discharge within the afferent population and thus facilitate the detection of weak stimuli.
Collapse
Affiliation(s)
- Ingvars Birznieks
- School of Science and Health, University of Western Sydney, Sydney, New South Wales, Australia.
| | | | | |
Collapse
|
36
|
Chvatal SA, Torres-Oviedo G, Safavynia SA, Ting LH. Common muscle synergies for control of center of mass and force in nonstepping and stepping postural behaviors. J Neurophysiol 2011; 106:999-1015. [PMID: 21653725 DOI: 10.1152/jn.00549.2010] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We investigated muscle activity, ground reaction forces, and center of mass (CoM) acceleration in two different postural behaviors for standing balance control in humans to determine whether common neural mechanisms are used in different postural tasks. We compared nonstepping responses, where the base of support is stationary and balance is recovered by returning CoM back to its initial position, with stepping responses, where the base of support is enlarged and balance is recovered by pushing the CoM away from the initial position. In response to perturbations of the same direction, these two postural behaviors resulted in different muscle activity and ground reaction forces. We hypothesized that a common pool of muscle synergies producing consistent task-level biomechanical functions is used to generate different postural behaviors. Two sets of support-surface translations in 12 horizontal-plane directions were presented, first to evoke stepping responses and then to evoke nonstepping responses. Electromyographs in 16 lower back and leg muscles of the stance leg were measured. Initially (∼100-ms latency), electromyographs, CoM acceleration, and forces were similar in nonstepping and stepping responses, but these diverged in later time periods (∼200 ms), when stepping occurred. We identified muscle synergies using non-negative matrix factorization and functional muscle synergies that quantified correlations between muscle synergy recruitment levels and biomechanical outputs. Functional muscle synergies that produce forces to restore CoM position in nonstepping responses were also used to displace the CoM during stepping responses. These results suggest that muscle synergies represent common neural mechanisms for CoM movement control under different dynamic conditions: stepping and nonstepping postural responses.
Collapse
Affiliation(s)
- Stacie A Chvatal
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech and Emory University, Atlanta, GA 30322-0535, USA
| | | | | | | |
Collapse
|