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Pan Z, Liu L, Sun Y, Ma Y. A Study of the Effects of Motor Experience on Neuromuscular Control Strategies During Sprint Starts. Motor Control 2024; 28:362-376. [PMID: 38710481 DOI: 10.1123/mc.2023-0149] [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: 12/17/2023] [Revised: 03/12/2024] [Accepted: 03/19/2024] [Indexed: 05/08/2024]
Abstract
Much of the current research on sprint start has attempted to analyze the biomechanical characteristics of elite athletes to provide guidance on the training of sprint technique, with less attention paid to the effects of motor experience gained from long-term training on neuromuscular control characteristics. The present study attempted to investigate the effect of motor experience on the modular organization of the neuromuscular system during starting, based on he clarification of the characteristics of muscle synergies during starting. It was found that exercise experience did not promote an increase in the number of synergies but rather a more focused timing of the activation of each synergy, allowing athletes to quickly complete the postural transition from crouching to running during the starting.
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Affiliation(s)
- Zhengye Pan
- College of Physical Education and Sports, Beijing Normal University, Beijing, China
| | - Lushuai Liu
- College of Physical Education and Sports, Beijing Normal University, Beijing, China
| | - Yuan Sun
- College of Physical Education and Sports, Beijing Normal University, Beijing, China
| | - Yunchao Ma
- College of Physical Education and Sports, Beijing Normal University, Beijing, China
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2
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Barliya A, Krausz N, Naaman H, Chiovetto E, Giese M, Flash T. Human arm redundancy: a new approach for the inverse kinematics problem. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231036. [PMID: 38420627 PMCID: PMC10898979 DOI: 10.1098/rsos.231036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/02/2024] [Indexed: 03/02/2024]
Abstract
The inverse kinematics (IK) problem addresses how both humans and robotic systems coordinate movement to resolve redundancy, as in the case of arm reaching where more degrees of freedom are available at the joint versus hand level. This work focuses on which coordinate frames best represent human movements, enabling the motor system to solve the IK problem in the presence of kinematic redundancies. We used a multi-dimensional sparse source separation method to derive sets of basis (or source) functions for both the task and joint spaces, with joint space represented by either absolute or anatomical joint angles. We assessed the similarities between joint and task sources in each of these joint representations, finding that the time-dependent profiles of the absolute reference frame's sources show greater similarity to corresponding sources in the task space. This result was found to be statistically significant. Our analysis suggests that the nervous system represents multi-joint arm movements using a limited number of basis functions, allowing for simple transformations between task and joint spaces. Additionally, joint space seems to be represented in an absolute reference frame to simplify the IK transformations, given redundancies. Further studies will assess this finding's generalizability and implications for neural control of movement.
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Affiliation(s)
- Avi Barliya
- Motor Control for Humans and Robotic Systems Laboratory, Weizmann Institute of Science, Rehovot, Central, Israel
| | - Nili Krausz
- Motor Control for Humans and Robotic Systems Laboratory, Weizmann Institute of Science, Rehovot, Central, Israel
- Neurobotics and Bionic Limbs (eNaBLe) Laboratory, Technion—Israel Institute of Technology, Haifa, Haifa, Israel
| | - Hila Naaman
- Motor Control for Humans and Robotic Systems Laboratory, Weizmann Institute of Science, Rehovot, Central, Israel
| | - Enrico Chiovetto
- Section Theoretical Sensomotorics, HIH/CIN, University Clinic of Tübingen, Tubingen, Baden-Württemberg, Germany
| | - Martin Giese
- Section Theoretical Sensomotorics, HIH/CIN, University Clinic of Tübingen, Tubingen, Baden-Württemberg, Germany
| | - Tamar Flash
- Motor Control for Humans and Robotic Systems Laboratory, Weizmann Institute of Science, Rehovot, Central, Israel
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3
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Leh A, Endres D, Hegele M. A primitive-based representation of dance: modulations by experience and perceptual validity. J Neurophysiol 2023; 130:1214-1225. [PMID: 37820011 DOI: 10.1152/jn.00161.2023] [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: 05/03/2023] [Revised: 10/05/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
The generation of complex movements such as dance might be possible due to the utilization of movement building blocks, i.e., movement primitives. However, it is largely unexplored how the temporal structure of a movement sequence and the recruitment of these primitives change with experience. Therefore, we obtained a representation of primitives with the temporal movement primitive model from the motion capture data of dancers with varying experiences, both for improvised and choreographed movements (elements from contemporary/modern/jazz) with different qualitative expressions. We analyzed differences between movement conditions regarding the number of temporal segments and the number of primitives, as well as their association with dance experience. Especially for the choreography with a neutral expression, the results indicate a negative association between experience and the number of segments and a positive association between experience and the number of primitives. The variation in the recruitment of these primitives suggests an increased consistency of modular control with experience, particularly for improvised dance. A prerequisite for the meaningful interpretation of these results regarding human movement production is that the model can generate perceptually valid dance movements. This was confirmed in a subsequent experiment, although the validity was slightly impaired for improvised movements. Overall, the results of the choreographed movement sequences suggest that experience is associated with an increase in motor repertoire that might facilitate fewer and longer temporal segments.NEW & NOTEWORTHY This study demonstrates that a temporal movement primitive model, trained with movements performed by dancers with different levels of experience, is able to generate natural-looking dance movements. The results suggest that motor experience in dance is associated not only with fewer temporal segments but also with an increase in the number of underlying movement building blocks. The recruitment of these primitives, which might be used to simplify movement production, additionally seems to become more consistent with experience.
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Affiliation(s)
- Amalaswintha Leh
- Neuromotor Behavior Laboratory, Department of Psychology and Sport Science, Justus Liebig University, Giessen, Germany
| | - Dominik Endres
- Theoretical Cognitive Science, Department of Psychology, Philipps-University Marburg, Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Giessen, Germany
| | - Mathias Hegele
- Neuromotor Behavior Laboratory, Department of Psychology and Sport Science, Justus Liebig University, Giessen, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Giessen, Germany
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4
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Flash T, Zullo L. Biomechanics, motor control and dynamic models of the soft limbs of the octopus and other cephalopods. J Exp Biol 2023; 226:307147. [PMID: 37083140 DOI: 10.1242/jeb.245295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Muscular hydrostats are organs composed entirely of packed arrays of incompressible muscles and lacking any skeletal support. Found in both vertebrates and invertebrates, they are of great interest for comparative biomechanics from engineering and evolutionary perspectives. The arms of cephalopods (e.g. octopus and squid) are particularly interesting muscular hydrostats because of their flexibility and ability to generate complex behaviors exploiting elaborate nervous systems. Several lines of evidence from octopus studies point to the use of both brain and arm-embedded motor control strategies that have evolved to simplify the complexities associated with the control of flexible and hyper-redundant limbs and bodies. Here, we review earlier and more recent experimental studies on octopus arm biomechanics and neural motor control. We review several dynamic models used to predict the kinematic characteristics of several basic motion primitives, noting the shortcomings of the current models in accounting for behavioral observations. We also discuss the significance of impedance (stiffness and viscosity) in controlling the octopus's motor behavior. These factors are considered in light of several new models of muscle biomechanics that could be used in future research to gain a better understanding of motor control in the octopus. There is also a need for updated models that encompass stiffness and viscosity for designing and controlling soft robotic arms. The field of soft robotics has boomed over the past 15 years and would benefit significantly from further progress in biomechanical and motor control studies on octopus and other muscular hydrostats.
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Affiliation(s)
- Tamar Flash
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Letizia Zullo
- Bioinspired Soft Robotics & Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
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5
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Chiovetto E, Salatiello A, d'Avella A, Giese MA. Toward a unifying framework for the modeling and identification of motor primitives. Front Comput Neurosci 2022; 16:926345. [PMID: 36172054 PMCID: PMC9510628 DOI: 10.3389/fncom.2022.926345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
A large body of evidence suggests that human and animal movements, despite their apparent complexity and flexibility, are remarkably structured. Quantitative analyses of various classes of motor behaviors consistently identify spatial and temporal features that are invariant across movements. Such invariant features have been observed at different levels of organization in the motor system, including the electromyographic, kinematic, and kinetic levels, and are thought to reflect fixed modules-named motor primitives-that the brain uses to simplify the construction of movement. However, motor primitives across space, time, and organization levels are often described with ad-hoc mathematical models that tend to be domain-specific. This, in turn, generates the need to use model-specific algorithms for the identification of both the motor primitives and additional model parameters. The lack of a comprehensive framework complicates the comparison and interpretation of the results obtained across different domains and studies. In this work, we take the first steps toward addressing these issues, by introducing a unifying framework for the modeling and identification of qualitatively different classes of motor primitives. Specifically, we show that a single model, the anechoic mixture model, subsumes many popular classes of motor primitive models. Moreover, we exploit the flexibility of the anechoic mixture model to develop a new class of identification algorithms based on the Fourier-based Anechoic Demixing Algorithm (FADA). We validate our framework by identifying eight qualitatively different classes of motor primitives from both simulated and experimental data. We show that, compared to established model-specific algorithms for the identification of motor primitives, our flexible framework reaches overall comparable and sometimes superior reconstruction performance. The identification framework is publicly released as a MATLAB toolbox (FADA-T, https://tinyurl.com/compsens) to facilitate the identification and comparison of different motor primitive models.
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Affiliation(s)
- Enrico Chiovetto
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience, Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
| | - Alessandro Salatiello
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience, Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
| | - Andrea d'Avella
- Laboratory of Neuromotor Physiology, IRCCS Fondazione Santa Lucia, Rome, Italy
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Martin A. Giese
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience, Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
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6
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Zhvansky DS, Sylos-Labini F, Dewolf A, Cappellini G, d’Avella A, Lacquaniti F, Ivanenko Y. Evaluation of Spatiotemporal Patterns of the Spinal Muscle Coordination Output during Walking in the Exoskeleton. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22155708. [PMID: 35957264 PMCID: PMC9370895 DOI: 10.3390/s22155708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 07/21/2022] [Accepted: 07/26/2022] [Indexed: 06/01/2023]
Abstract
Recent advances in the performance and evaluation of walking in exoskeletons use various assessments based on kinematic/kinetic measurements. While such variables provide general characteristics of gait performance, only limited conclusions can be made about the neural control strategies. Moreover, some kinematic or kinetic parameters are a consequence of the control implemented on the exoskeleton. Therefore, standard indicators based on kinematic variables have limitations and need to be complemented by performance measures of muscle coordination and control strategy. Knowledge about what happens at the spinal cord output level might also be critical for rehabilitation since an abnormal spatiotemporal integration of activity in specific spinal segments may result in a risk for abnormalities in gait recovery. Here we present the PEPATO software, which is a benchmarking solution to assess changes in the spinal locomotor output during walking in the exoskeleton with respect to reference data on normal walking. In particular, functional and structural changes at the spinal cord level can be mapped into muscle synergies and spinal maps of motoneuron activity. A user-friendly software interface guides the user through several data processing steps leading to a set of performance indicators as output. We present an example of the usage of this software for evaluating walking in an unloading exoskeleton that allows a person to step in simulated reduced (the Moon's) gravity. By analyzing the EMG activity from lower limb muscles, the algorithms detected several performance indicators demonstrating differential adaptation (shifts in the center of activity, prolonged activation) of specific muscle activation modules and spinal motor pools and increased coactivation of lumbar and sacral segments. The software is integrated at EUROBENCH facilities to benchmark the performance of walking in the exoskeleton from the point of view of changes in the spinal locomotor output.
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Affiliation(s)
- Dmitry S. Zhvansky
- Institute for Information Transmission Problems, Russian Academy of Sciences, 127994 Moscow, Russia;
| | - Francesca Sylos-Labini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Arthur Dewolf
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Andrea d’Avella
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, 98100 Messina, Italy
| | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
- Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179 Rome, Italy; (F.S.-L.); (A.D.); (G.C.); (A.d.); (F.L.)
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7
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Tricomi E, Lotti N, Missiroli F, Zhang X, Xiloyannis M, Muller T, Crea S, Papp E, Krzywinski J, Vitiello N, Masia L. Underactuated Soft Hip Exosuit Based on Adaptive Oscillators to Assist Human Locomotion. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2021.3136240] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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8
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Cutler HR, Hodson-Tole E. The repeatability of neuromuscular activation strategies recorded in recreationally active individuals during cycling. Eur J Appl Physiol 2022; 122:1045-1057. [PMID: 35166903 PMCID: PMC8927038 DOI: 10.1007/s00421-022-04899-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 01/21/2022] [Indexed: 11/29/2022]
Abstract
Purpose The human neuro-motor system can select different intermuscular coordination patterns to complete any given task, such as pedalling a bicycle. This study assessed whether intermuscular coordination patterns are used consistently across visit days and cadence conditions in recreationally active individuals. Methods Seven participants completed a cycling exercise protocol across 2 days, consisting of pedalling at 150 Watts at cadences of 60, 80 and 100 rpm. Whilst cycling, surface electromyography was continuously recorded from ten leg muscles. For each participant, muscle coordination patterns were established using principal component (PC) analysis and the amount that each pattern was used was quantified by the PC loading scores. A sample entropy derived measure of the persistence of the loading scores across consecutive pedal cycles, entropic half-life (EnHL), was calculated. The median loading scores and EnHLs of the first three PCs were then compared across cadence conditions and visit days. Results No significant differences were found in the median loading scores across cadence conditions or visits, nor were there any significant differences in the EnHLs across visits. However, the EnHLs were significantly longer when participants were cycling at 60 rpm compared to 100 rpm. Conclusion These findings are based on a small sample size, but do suggest that, within individual participants, a consistent neuromuscular control strategy is used during cycling on different days. However, the underlying structure of muscle coordination is more persistent when pedalling at slower cadences with large differences between individuals.
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Affiliation(s)
- Hannah R Cutler
- Musculoskeletal Science and Sports Medicine Research Centre, Dpt. Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Emma Hodson-Tole
- Musculoskeletal Science and Sports Medicine Research Centre, Dpt. Life Sciences, Manchester Metropolitan University, Manchester, UK. .,Manchester Metropolitan University Institute of Sport, Manchester, UK.
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9
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Abstract
Memory recollections and voluntary actions are often perceived as spontaneously generated irrespective of external stimuli. Although products of our neurons, they are only rarely accessible in humans at the neuronal level. Here I review insights gleaned from unique neurosurgical opportunities to record and stimulate single-neuron activity in people who can declare their thoughts, memories and wishes. I discuss evidence that the subjective experience of human recollection and that of voluntary action arise from the activity of two internal neuronal generators, the former from medial temporal lobe reactivation and the latter from frontoparietal preactivation. I characterize properties of these generators and their interaction, enabling flexible recruitment of memory-based choices for action as well as recruitment of action-based plans for the representation of conceptual knowledge in memories. Both internal generators operate on surprisingly explicit but different neuronal codes, which appear to arise with distinct single-neuron activity, often observed before participants' reports of conscious awareness. I discuss prediction of behaviour based on these codes, and the potential for their modulation. The prospects of editing human memories and volitions by enhancement, inception or deletion of specific, selected content raise therapeutic possibilities and ethical concerns.
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10
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Divjak M, Sedej G, Murks N, Gerževič M, Marusic U, Pišot R, Šimunič B, Holobar A. Inter-Person Differences in Isometric Coactivations of Triceps Surae and Tibialis Anterior Decrease in Young, but Not in Older Adults After 14 Days of Bed Rest. Front Physiol 2022; 12:809243. [PMID: 35153817 PMCID: PMC8832055 DOI: 10.3389/fphys.2021.809243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
We examined activation patterns of the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), soleus (SO), and tibialis anterior (TA) muscles in eight older (58.4 ± 3.3 years) and seven young (23.1 ± 2.9 years) participants, before and after 14 days of horizontal bed rest. Visual feedback on the exerted muscle torque was provided to the participants. The discharge patterns of individual motor units (MUs) were studied in three repetitions of isometric plantar flexion at 30 and 60% of Maximum Voluntary Contraction (MVC), before, and 1 day after the 14-day bed rest, respectively. In the GL and GM muscles, the older participants demonstrated higher MU discharge rates than the young, regardless of the contraction level, both before and after the bed rest. In the TA and SO muscles, the differences between the older and young participants were less consistent. Detailed analysis revealed person-specific changes in the MU discharge rates after the bed rest. To quantify the coactivation patterns we calculated the correlation coefficients between the cumulative spike trains of identified MUs from each muscle, and measured the root mean square difference of the correlation coefficients between the trials of the same session (intra-session variability) and between different sessions (inter-session variability) in each participant (intra-person comparison) and across participants (inter-person comparison). In the intra-person comparison, the inter-session variability was higher than the intra-session variability, either before or after the bed rest. At 60% MVC torque, the young demonstrated higher inter-person variability of coactivation than the older participants, but this variability decreased significantly after the bed rest. In older participants, inter-person variability was consistently lower at 60% than at 30% MVC torque. In young participants, inter-person variability became lower at 60% than at 30% MVC torque only after the bed rest. Precaution is required when analyzing the MU discharge and coactivation patterns, as individual persons demonstrate individual adaptations to aging or bed rest.
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Affiliation(s)
- Matjaž Divjak
- System Software Laboratory, Institute of Computer Science, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Gašper Sedej
- System Software Laboratory, Institute of Computer Science, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Nina Murks
- System Software Laboratory, Institute of Computer Science, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Mitja Gerževič
- Science and Research Centre Koper, Institute for Kinesiology Research, Koper, Slovenia
- Department of Health Sciences, Alma Mater Europaea – ECM, Maribor, Slovenia
| | - Uros Marusic
- Science and Research Centre Koper, Institute for Kinesiology Research, Koper, Slovenia
- Department of Health Sciences, Alma Mater Europaea – ECM, Maribor, Slovenia
| | - Rado Pišot
- Science and Research Centre Koper, Institute for Kinesiology Research, Koper, Slovenia
| | - Boštjan Šimunič
- Science and Research Centre Koper, Institute for Kinesiology Research, Koper, Slovenia
| | - Aleš Holobar
- System Software Laboratory, Institute of Computer Science, Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
- *Correspondence: Aleš Holobar,
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11
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Bernier PM, Mathew J, Danion FR. Composition and decomposition of visuomotor maps during manual tracking. J Neurophysiol 2021; 126:1685-1697. [PMID: 34614368 DOI: 10.1152/jn.00058.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adapting hand movements to changes in our body or the environment is essential for skilled motor behavior, as is the ability to flexibly combine experience gathered in separate contexts. However, it has been shown that when adapting hand movements to two different visuomotor perturbations in succession, interference effects can occur. Here, we investigate whether these interference effects compromise our ability to adapt to the superposition of the two perturbations. Participants tracked with a joystick, a visual target that followed a smooth but an unpredictable trajectory. Four separate groups of participants (total n = 83) completed one block of 50 trials under each of three mappings: one in which the cursor was rotated by 90° (ROTATION), one in which the cursor mimicked the behavior of a mass-spring system (SPRING), and one in which the SPRING and ROTATION mappings were superimposed (SPROT). The order of the blocks differed across groups. Although interference effects were found when switching between SPRING and ROTATION, participants who performed these blocks first performed better in SPROT than participants who had no prior experience with SPRING and ROTATION (i.e., composition). Moreover, participants who started with SPROT exhibited better performance under SPRING and ROTATION than participants who had no prior experience with each of these mappings (i.e., decomposition). Additional analyses confirmed that these effects resulted from components of learning that were specific to the rotational and spring perturbations. These results show that interference effects do not preclude the ability to compose/decompose various forms of visuomotor adaptation.NEW & NOTEWORTHY The ability to compose/decompose task representations is critical for both cognitive and behavioral flexibility. Here, we show that this ability extends to two forms of visuomotor adaptation in which humans have to perform visually guided hand movements. Despite the presence of interference effects when switching between visuomotor maps, we show that participants are able to flexibly compose or decompose knowledge acquired in previous sessions. These results further demonstrate the flexibility of sensorimotor adaptation in humans.
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Affiliation(s)
- Pierre-Michel Bernier
- Département de Kinanthropologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - James Mathew
- Institut Neurosci Timone, Aix Marseille Univ, CNRS, INT, Marseille, France.,Institute of Neuroscience, Institute of Communication & Information Technologies, Electronics & Applied Mathematics, Université Catholique de Louvain, Louvain-la-neuve, Belgium
| | - Frederic R Danion
- Institut Neurosci Timone, Aix Marseille Univ, CNRS, INT, Marseille, France.,Center for Research on Cognition and Learning (CERCA) UMR 7295, University of Poitiers, CNRS, Poitiers, France
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12
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Hong YNG, Ballekere AN, Fregly BJ, Roh J. Are muscle synergies useful for stroke rehabilitation? CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021. [DOI: 10.1016/j.cobme.2021.100315] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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13
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Tanzarella S, Muceli S, Santello M, Farina D. Synergistic Organization of Neural Inputs from Spinal Motor Neurons to Extrinsic and Intrinsic Hand Muscles. J Neurosci 2021; 41:6878-6891. [PMID: 34210782 PMCID: PMC8360692 DOI: 10.1523/jneurosci.0419-21.2021] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 11/21/2022] Open
Abstract
Our current understanding of synergistic muscle control is based on the analysis of muscle activities. Modules (synergies) in muscle coordination are extracted from electromyographic (EMG) signal envelopes. Each envelope indirectly reflects the neural drive received by a muscle; therefore, it carries information on the overall activity of the innervating motor neurons. However, it is not known whether the output of spinal motor neurons, whose number is orders of magnitude greater than the muscles they innervate, is organized in a low-dimensional fashion when performing complex tasks. Here, we hypothesized that motor neuron activities exhibit a synergistic organization in complex tasks and therefore that the common input to motor neurons results in a large dimensionality reduction in motor neuron outputs. To test this hypothesis, we factorized the output spike trains of motor neurons innervating 14 intrinsic and extrinsic hand muscles and analyzed the dimensionality of control when healthy individuals exerted isometric forces using seven grip types. We identified four motor neuron synergies, accounting for >70% of the variance of the activity of 54.1 ± 12.9 motor neurons, and we identified four functionally similar muscle synergies. However, motor neuron synergies better discriminated individual finger forces than muscle synergies and were more consistent with the expected role of muscles actuating each finger. Moreover, in a few cases, motor neurons innervating the same muscle were active in separate synergies. Our findings suggest a highly divergent net neural inputs to spinal motor neurons from spinal and supraspinal structures, contributing to the dimensionality reduction captured by muscle synergies.SIGNIFICANCE STATEMENT We addressed whether the output of spinal motor neurons innervating multiple hand muscles could be accounted for by a modular organization, i.e., synergies, previously described to account for the coordination of multiple muscles. We found that motor neuron synergies presented similar dimensionality (implying a >10-fold reduction in dimensionality) and structure as muscle synergies. Nonetheless, the synergistic behavior of subsets of motor neurons within a muscle was also observed. These results advance our understanding of how neuromuscular control arises from mapping descending inputs to muscle activation signals. We provide, for the first time, insights into the organization of neural inputs to spinal motor neurons which, to date, has been inferred through analysis of muscle synergies.
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Affiliation(s)
- Simone Tanzarella
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Silvia Muceli
- Division of Signal Processing and Biomedical Engineering, Department of Electrical Engineering, Chalmers University of Technology, Gothenburg 412 96, Sweden
| | - Marco Santello
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287-9709
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
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14
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Huang B, Xiong C, Chen W, Liang J, Sun BY, Gong X. Common kinematic synergies of various human locomotor behaviours. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210161. [PMID: 33996133 PMCID: PMC8059590 DOI: 10.1098/rsos.210161] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
Humans show a variety of locomotor behaviours in daily living, varying in locomotor modes and interaction styles with the external environment. However, how this excellent motor ability is formed, whether there are some invariants underlying various locomotor behaviours and simplifying their generation, and what factors contribute to the invariants remain unclear. Here, we find three common kinematic synergies that form the six joint motions of one lower limb during walking, running, hopping and sitting-down-standing-up (movement variance accounted for greater than 90%), through identifying the coordination characteristics of 36 lower limb motor tasks in diverse environments. This finding supports the notion that humans simplify the generation of various motor behaviours through re-using several basic motor modules, rather than developing entirely new modules for each behaviour. Moreover, a potential link is also found between these synergies and the unique biomechanical characteristics of the human musculoskeletal system (muscular-articular connective architecture and bone shape), and the patterns of inter-joint coordination are consistent with the energy-saving mechanism in locomotion by using biarticular muscles as efficient mechanical energy transducers between joints. Altogether, our work helps understand the formation mechanisms of human locomotion from a holistic viewpoint and evokes inspirations for the development of artificial limbs imitating human motor ability.
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Affiliation(s)
- Bo Huang
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Caihua Xiong
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Wenbin Chen
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Jiejunyi Liang
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Bai-Yang Sun
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
| | - Xuan Gong
- Institute of Robotics Research (IR2), State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, People's Republic of China
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15
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Cheung VCK, Seki K. Approaches to revealing the neural basis of muscle synergies: a review and a critique. J Neurophysiol 2021; 125:1580-1597. [PMID: 33729869 DOI: 10.1152/jn.00625.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The central nervous system (CNS) may produce coordinated motor outputs via the combination of motor modules representable as muscle synergies. Identification of muscle synergies has hitherto relied on applying factorization algorithms to multimuscle electromyographic data (EMGs) recorded during motor behaviors. Recent studies have attempted to validate the neural basis of the muscle synergies identified by independently retrieving the muscle synergies through CNS manipulations and analytic techniques such as spike-triggered averaging of EMGs. Experimental data have demonstrated the pivotal role of the spinal premotor interneurons in the synergies' organization and the presence of motor cortical loci whose stimulations offer access to the synergies, but whether the motor cortex is also involved in organizing the synergies has remained unsettled. We argue that one difficulty inherent in current approaches to probing the synergies' neural basis is that the EMG generative model based on linear combination of synergies and the decomposition algorithms used for synergy identification are not grounded on enough prior knowledge from neurophysiology. Progress may be facilitated by constraining or updating the model and algorithms with knowledge derived directly from CNS manipulations or recordings. An investigative framework based on evaluating the relevance of neurophysiologically constrained models of muscle synergies to natural motor behaviors will allow a more sophisticated understanding of motor modularity, which will help the community move forward from the current debate on the neural versus nonneural origin of muscle synergies.
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Affiliation(s)
- Vincent C K Cheung
- School of Biomedical Sciences and The Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, Hong Kong, China
| | - Kazuhiko Seki
- Department of Neurophysiology, National Institute of Neuroscience, Kodaira, Tokyo, Japan
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16
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Cappellini G, Sylos-Labini F, Assenza C, Libernini L, Morelli D, Lacquaniti F, Ivanenko Y. Clinical Relevance of State-of-the-Art Analysis of Surface Electromyography in Cerebral Palsy. Front Neurol 2020; 11:583296. [PMID: 33362693 PMCID: PMC7759523 DOI: 10.3389/fneur.2020.583296] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
Surface electromyography (sEMG) can be used to assess the integrity of the neuromuscular system and its impairment in neurological disorders. Here we will consider several issues related to the current clinical applications, difficulties and limited usage of sEMG for the assessment and rehabilitation of children with cerebral palsy. The uniqueness of this methodology is that it can determine hyperactivity or inactivity of selected muscles, which cannot be assessed by other methods. In addition, it can assist for intervention or muscle/tendon surgery acts, and it can evaluate integrated functioning of the nervous system based on multi-muscle sEMG recordings and assess motor pool activation. The latter aspect is especially important for understanding impairments of the mechanisms of neural controllers rather than malfunction of individual muscles. Although sEMG study is an important tool in both clinical research and neurorehabilitation, the results of a survey on the clinical relevance of sEMG in a typical department of pediatric rehabilitation highlighted its limited clinical usage. We believe that this is due to limited knowledge of the sEMG and its neuromuscular underpinnings by many physiotherapists, as a result of lack of emphasis on this important methodology in the courses taught in physical therapy schools. The lack of reference databases or benchmarking software for sEMG analysis may also contribute to the limited clinical usage. Despite the existence of educational and technical barriers to a widespread use of, sEMG does provide important tools for planning and assessment of rehabilitation treatments for children with cerebral palsy.
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Affiliation(s)
- Germana Cappellini
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | | | - Carla Assenza
- Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Laura Libernini
- Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Daniela Morelli
- Department of Pediatric Neurorehabilitation, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Francesco Lacquaniti
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.,Department of Systems Medicine, Centre of Space Bio-medicine, University of Rome Tor Vergata, Rome, Italy
| | - Yury Ivanenko
- Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy
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Nassour J, Duy Hoa T, Atoofi P, Hamker F. Concrete Action Representation Model: From Neuroscience to Robotics. IEEE Trans Cogn Dev Syst 2020. [DOI: 10.1109/tcds.2019.2896300] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Schilling M, Cruse H. Decentralized control of insect walking: A simple neural network explains a wide range of behavioral and neurophysiological results. PLoS Comput Biol 2020; 16:e1007804. [PMID: 32339162 PMCID: PMC7205325 DOI: 10.1371/journal.pcbi.1007804] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 05/07/2020] [Accepted: 03/19/2020] [Indexed: 01/02/2023] Open
Abstract
Controlling the six legs of an insect walking in an unpredictable environment is a challenging task, as many degrees of freedom have to be coordinated. Solutions proposed to deal with this task are usually based on the highly influential concept that (sensory-modulated) central pattern generators (CPG) are required to control the rhythmic movements of walking legs. Here, we investigate a different view. To this end, we introduce a sensor based controller operating on artificial neurons, being applied to a (simulated) insectoid robot required to exploit the "loop through the world" allowing for simplification of neural computation. We show that such a decentralized solution leads to adaptive behavior when facing uncertain environments which we demonstrate for a broad range of behaviors never dealt with in a single system by earlier approaches. This includes the ability to produce footfall patterns such as velocity dependent "tripod", "tetrapod", "pentapod" as well as various stable intermediate patterns as observed in stick insects and in Drosophila. These patterns are found to be stable against disturbances and when starting from various leg configurations. Our neuronal architecture easily allows for starting or interrupting a walk, all being difficult for CPG controlled solutions. Furthermore, negotiation of curves and walking on a treadmill with various treatments of individual legs is possible as well as backward walking and performing short steps. This approach can as well account for the neurophysiological results usually interpreted to support the idea that CPGs form the basis of walking, although our approach is not relying on explicit CPG-like structures. Application of CPGs may however be required for very fast walking. Our neuronal structure allows to pinpoint specific neurons known from various insect studies. Interestingly, specific common properties observed in both insects and crustaceans suggest a significance of our controller beyond the realm of insects.
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Affiliation(s)
- Malte Schilling
- Cluster of Excellence Cognitive Interactive Technology (CITEC), Bielefeld University, Bielefeld, Germany
| | - Holk Cruse
- Cluster of Excellence Cognitive Interactive Technology (CITEC), Bielefeld University, Bielefeld, Germany
- Biological Cybernetics, Faculty of Biology, Bielefeld University, Bielefeld, Germany
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Steinbeck F, Adden A, Graham P. Connecting brain to behaviour: a role for general purpose steering circuits in insect orientation? J Exp Biol 2020; 223:223/5/jeb212332. [DOI: 10.1242/jeb.212332] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
ABSTRACT
The lateral accessory lobes (LALs), paired structures that are homologous among all insect species, have been well studied for their role in pheromone tracking in silkmoths and phonotaxis in crickets, where their outputs have been shown to correlate with observed motor activity. Further studies have shown more generally that the LALs are crucial both for an insect's ability to steer correctly and for organising the outputs of the descending pathways towards the motor centres. In this context, we propose a framework by which the LALs may be generally involved in generating steering commands across a variety of insects and behaviours. Across different behaviours, we see that the LAL is involved in generating two kinds of steering: (1) search behaviours and (2) targeted steering driven by direct sensory information. Search behaviours are generated when the current behaviourally relevant cues are not available, and a well-described LAL subnetwork produces activity which increases sampling of the environment. We propose that, when behaviourally relevant cues are available, the LALs may integrate orientation information from several sensory modalities, thus leading to a collective output for steering driven by those cues. These steering commands are then sent to the motor centres, and an additional efference copy is sent back to the orientation-computing areas. In summary, we have taken known aspects of the neurophysiology and function of the insect LALs and generated a speculative framework that suggests how LALs might be involved in steering control for a variety of complex real-world behaviours in insects.
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Affiliation(s)
- Fabian Steinbeck
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Andrea Adden
- Department of Biology, Lund University, 223 62 Lund, Sweden
| | - Paul Graham
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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20
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Short MR, Damiano DL, Kim Y, Bulea TC. Children With Unilateral Cerebral Palsy Utilize More Cortical Resources for Similar Motor Output During Treadmill Gait. Front Hum Neurosci 2020; 14:36. [PMID: 32153376 PMCID: PMC7047842 DOI: 10.3389/fnhum.2020.00036] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/27/2020] [Indexed: 12/23/2022] Open
Abstract
Children with unilateral cerebral palsy (CP) walk independently although with an asymmetrical, more poorly coordinated pattern compared to their peers. While gait biomechanics in unilateral CP and their alteration from those without CP have been well documented, cortical mechanisms underlying gait remain inadequately understood. To the best of our knowledge, this is the first study utilizing electroencephalography (EEG) during treadmill gait in older children with and without CP. Lower limb surface electromyographic (EMG) data were collected and muscle synergy analyses performed to quantify motor output. Our primary goal was to evaluate the relationships between cortical and muscle activation within and across groups and hemispheres to provide novel insights into neural control of gait and how it may be disrupted by an early unilateral brain injury. Participants included 9 children with unilateral CP, mean age 16.0 ± 2.7 years, and 12 with typical development (TD), mean age 14.8 ± 3.0 years. EEG data were collected during a standing baseline and treadmill walking at self-selected speed. EMG of 16 lower limb muscles were also collected bilaterally and synchronized with EEG. No significant group differences were found in synergy number or structure across groups. Six cortical clusters were identified as having gait-related activation and all contained participants from both CP and TD groups; however, the percent of individuals per group appearing in different clusters varied. Notably, the cluster least represented in CP was the non-dominant motor region. Both groups showed mu-band ERD in the motor clusters during gait although sustained beta-band ERD was not evident in TD. The CP group showed greater cortical activation than TD during walking as measured by mu- and beta-ERD in the dominant and non-dominant motor and parietal regions and elevated low gamma-activity in the frontal and parietal areas, a unique finding in CP. CP showed greater bilateral motor EEG-EMG coherence in the gamma-band with the hallucis longus compared to TD. In summary, individuals with CP display increased cortical activation during gait possibly relating to differences in distal motor control of the more affected side. Strategies that iteratively reduce cortical activation while improving selective motor control are needed in CP.
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Affiliation(s)
- Matthew R. Short
- Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, United States
| | - Diane L. Damiano
- Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, United States
| | - Yushin Kim
- Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, United States
- Sports Health Rehabilitation, Cheongju University, Cheongju, South Korea
| | - Thomas C. Bulea
- Functional and Applied Biomechanics Section, Rehabilitation Medicine Department, National Institutes of Health, Bethesda, MD, United States
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21
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Modular Organization of Muscle Synergies to Achieve Movement Behaviors. JOURNAL OF HEALTHCARE ENGINEERING 2019; 2019:8130297. [PMID: 31827741 PMCID: PMC6885185 DOI: 10.1155/2019/8130297] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/21/2019] [Indexed: 12/30/2022]
Abstract
Muscle synergy has been applied to comprehend how the central nervous system (CNS) controls movements for decades. However, it is not clear about the motion control mechanism and the relationship between motions and muscle synergies. In this paper, we designed two experiments to corroborate the hypothesis: (1) motions can be decomposed to motion primitives, which are driven by muscle synergy primitives and (2) variations of motion primitives in direction and scale are modulated by activation coefficients rather than muscle synergy primitives. Surface electromyographic (EMG) signals were recorded from nine muscles of the upper limb. Nonnegative matrix factorization (NMF) was applied to extract muscle synergy vectors and corresponding activation coefficients. We found that synergy structures of different movement patterns were similar (α=0.05). The motion modulation indexes (MMI) among movement patterns in reaching movements showed apparent differences. Merging coefficients and reconstructed similarity of synergies between simple motions and complex motions were significant. This study revealed the motion control mechanism of the CNS and provided a rehabilitation and evaluation method for patients with motor dysfunction in exercise and neuroscience.
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22
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Averta G, Valenza G, Catrambone V, Barontini F, Scilingo EP, Bicchi A, Bianchi M. On the Time-Invariance Properties of Upper Limb Synergies. IEEE Trans Neural Syst Rehabil Eng 2019; 27:1397-1406. [DOI: 10.1109/tnsre.2019.2918311] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Computational assessment of long-term memory structures from SDA-M related to action sequences. PLoS One 2019; 14:e0212414. [PMID: 30794606 PMCID: PMC6386273 DOI: 10.1371/journal.pone.0212414] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/02/2019] [Indexed: 12/14/2022] Open
Abstract
Assistance systems should be able to adapt to individual task-related skills and knowledge. Structural-dimensional analysis of mental representations (SDA-M) is an established method for retrieving human memory structures related to specific activities. For this purpose, SDA-M involves a semi-automatized survey of users (the “split procedure”), which yields data about users’ associations between action representations in long-term memory. Up to now this data about associations has commonly been clustered and visualized by SDA-M software in the form of dendrograms that can be used by human experts as a tool to (manually) assess users’ individual expertise and identify potential issues with respect to predefined action sequences. This article presents new algorithmic approaches for automatizing the process of assessing task-related memory structures based on SDA-M data to predict probable errors in action sequences. This automation enables direct integration into technical systems, e.g. user-adaptive assistance systems. An evaluation study has compared the automatized computational assessments to predictions made by human scholars based on visualizations of SDA-M data. The different algorithms’ outputs matched human experts’ manual assessments in 84% to 86% of the test cases.
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Savc M, Glaser V, Holobar A. On the Impact of Muscle Shortening on Non-Negative Matrix Factorization of Dynamic Surface Electromyograms. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:5970-5973. [PMID: 30441696 DOI: 10.1109/embc.2018.8513670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We analyzed the sensitivity of Non-negative Matrix Factorization (NMF) of dynamic surface electromyograms (EMG) to muscle shortening. We first identified Motor unit action potentials (MUAPs) by decomposing experimentally recorded EMG signals during slow shortening of biceps brachii muscle in five young healthy males. We then used these MUAPs to generate different synthetic EMG signals with different muscle shortening and excitation profiles. Afterwards, we applied NMF to the synthetic EMG signals and calculated Pearson correlation coefficient (CC) between the extracted NMF components and a) muscle shortening and b) muscle excitation profiles. The results demonstrated good match between NMF components and muscle excitation profiles, but only when the muscle excitation level changed for at least 10 % during the muscle shortening. During constant muscle excitation, the resulting NMF components correlated significantly with the muscle shortening profiles. These results demonstrate that NMF components reflect not only the muscle excitation profiles but also muscle shortening profiles. Therefore, the results of NMF analysis of dynamic EMG signals need to be interpreted with caution.
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25
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Scheidler AM, Kinnett-Hopkins D, Learmonth YC, Motl R, López-Ortiz C. Targeted ballet program mitigates ataxia and improves balance in females with mild-to-moderate multiple sclerosis. PLoS One 2018; 13:e0205382. [PMID: 30335774 PMCID: PMC6193654 DOI: 10.1371/journal.pone.0205382] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/25/2018] [Indexed: 11/30/2022] Open
Abstract
Background Multiple sclerosis (MS) is a disease of the central nervous system that causes ataxia and deficits in balance. Exercise-based therapies have been identified as integral to the recovery of motor function in MS, but few studies have investigated non-traditional movement interventions. We examined a targeted ballet program (TBP) designed to mitigate ataxia and improve balance in females with mild-to-moderate relapsing-remitting MS. Methods and findings Twelve females with mild-to-moderate disability due to MS were assessed for study eligibility for the study. Ten participants met the inclusion criteria. Two were lost to unrelated health complications. Eight participants completed the TBP. The TBP met twice a week for 60 minutes for 16 weeks. Assessments included (a) the International Cooperative Ataxia Rating Scale (ICARS), (b) the Mini-Balance Evaluations Systems Test (Mini-BESTest), (c) smoothness of movement during a five-meter walk, and (d) balance in a step to stand task before and after the TBP. There were no TBP-related adverse events. Single-tailed paired samples t-tests and Wilcoxon tests were conducted. Improvements were observed in ICARS (p = 7.11E-05), Mini-BESTest (p = 0.001), smoothness of movement in the left (p = 0.027) and right (p = 0.028) sides of the body, and balance in a step-to-stand task in the back (p = 0.025) direction. Results yielded 42% and 58% improvements in the mean Mini-BESTest and ICARS scores, respectively. Conclusions This study adds to current research by providing support for a TBP intervention targeting ataxia and balance in MS. The TBP was well tolerated, improved balance, and mitigated ataxia. Clinical improvements were larger than those of previous studies on physical rehabilitation in MS with similar outcome measures. Trial registration ISRCTN ISRCTN67916624.
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Affiliation(s)
- Andrew M. Scheidler
- Department of Kinesiology and Community Health, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Dominique Kinnett-Hopkins
- Department of Kinesiology and Community Health, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Yvonne C. Learmonth
- Department of Kinesiology and Community Health, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Robert Motl
- Department of Kinesiology and Community Health, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Citlali López-Ortiz
- Department of Kinesiology and Community Health, University of Illinois, Urbana-Champaign, Illinois, United States of America
- Joffrey Ballet Academy, The Official School of the Joffrey Ballet, Chicago, Illinois, United States of America
- * E-mail:
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Savc M, Glaser V, Kranjec J, Cikajlo I, Matjacic Z, Holobar A. Comparison of Convolutive Kernel Compensation and Non-Negative Matrix Factorization of Surface Electromyograms. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1935-1944. [PMID: 30281464 DOI: 10.1109/tnsre.2018.2869426] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We compared non-negative matrix factorization (NMF) and convolution kernel compensation techniques for high-density electromyogram decomposition. The experimental data were recorded from nine healthy persons during controlled single degree of freedom (DOF) wrist flexion-extension, supination-pronation, and ulnar-radial deviation movements. We assembled the identified motor units and NMF components into three groups. Those active mostly during the first and the second movement direction per DOF were placed in the G1 and G3 groups, respectively. The remaining components were nonspecific for movement direction and were placed in the G2 group. In ulnar and radial deviation, the relative energies of identified cumulative motor unit spike trains (CSTs) and NMF components were similarly distributed among the groups. In other two movement types, the energy of NMF components in the G2 group was significantly larger than the energy of CSTs. We further performed a coherence analysis between CSTs and sums of NMF components in each group. Both decompositions demonstrated a solid match, but only at frequencies <3 Hz. At higher frequencies, the coherence hardly exceeded the value of 0.5. Potential reasons for these discrepancies include the negative impact of motor unit action potential shapes and noise on NMF decomposition.
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Bruton M, O'Dwyer N. Synergies in coordination: a comprehensive overview of neural, computational, and behavioral approaches. J Neurophysiol 2018; 120:2761-2774. [PMID: 30281388 DOI: 10.1152/jn.00052.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
At face value, the term "synergy" provides a unifying concept within a fractured field that encompasses complementary neural, computational, and behavioral approaches. However, the term is not used synonymously by different researchers but has substantially different meanings depending on the research approach. With so many operational definitions for the one term, it becomes difficult to use as either a descriptive or explanatory concept, yet it remains pervasive and apparently indispensable. Here we provide a summary of different approaches that invoke synergies in a descriptive or explanatory context, summarizing progress, not within the one approach, but across the theoretical landscape. Bernstein's framework of flexible hierarchical control may provide a unifying framework here, since it can incorporate divergent ideas about synergies. In the current motor control literature, synergy may refer to conceptually different processes that could potentially operate in parallel, across different levels within the same hierarchical control scheme. There is evidence for the concurrent existence of synergies with different features, both "hard-wired" and "soft-wired," and task independent and task dependent. By providing a comprehensive overview of the multifaceted ideas about synergies, our goal is to move away from the compartmentalization and narrow the focus on one level and promote a broader perspective on the control and coordination of movement.
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Affiliation(s)
- Michaela Bruton
- School of Exercise Science, Australian Catholic University, Strathfield, New South Wales , Australia
| | - Nicholas O'Dwyer
- Discipline of Exercise and Sport Science, The University of Sydney , Sydney, New South Wales , Australia.,School of Exercise Science, Sport, and Health, Charles Sturt University, Bathurst, New South Wales , Australia
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28
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Inzelberg L, Rand D, Steinberg S, David-Pur M, Hanein Y. A Wearable High-Resolution Facial Electromyography for Long Term Recordings in Freely Behaving Humans. Sci Rep 2018; 8:2058. [PMID: 29391503 PMCID: PMC5794977 DOI: 10.1038/s41598-018-20567-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/21/2018] [Indexed: 11/23/2022] Open
Abstract
Human facial expressions are a complex capacity, carrying important psychological and neurological information. Facial expressions typically involve the co-activation of several muscles; they vary between individuals, between voluntary versus spontaneous expressions, and depend strongly on personal interpretation. Accordingly, while high-resolution recording of muscle activation in a non-laboratory setting offers exciting opportunities, it remains a major challenge. This paper describes a wearable and non-invasive method for objective mapping of facial muscle activation and demonstrates its application in a natural setting. We focus on muscle activation associated with "enjoyment", "social" and "masked" smiles; three categories with distinct social meanings. We use an innovative, dry, soft electrode array designed specifically for facial surface electromyography recording, a customized independent component analysis algorithm, and a short training procedure to achieve the desired mapping. First, identification of the orbicularis oculi and the levator labii superioris was demonstrated from voluntary expressions. Second, the zygomaticus major was identified from voluntary and spontaneous Duchenne and non-Duchenne smiles. Finally, using a wireless device in an unmodified work environment revealed expressions of diverse emotions in face-to-face interaction. Our high-resolution and crosstalk-free mapping, along with excellent user-convenience, opens new opportunities in gaming, virtual-reality, bio-feedback and objective psychological and neurological assessment.
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Affiliation(s)
- Lilah Inzelberg
- Tel Aviv University Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel.
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - David Rand
- Tel Aviv University Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
| | | | - Moshe David-Pur
- Tel Aviv University Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Yael Hanein
- Tel Aviv University Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Ingram JN, Sadeghi M, Flanagan JR, Wolpert DM. An error-tuned model for sensorimotor learning. PLoS Comput Biol 2017; 13:e1005883. [PMID: 29253869 PMCID: PMC5749863 DOI: 10.1371/journal.pcbi.1005883] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/02/2018] [Accepted: 11/17/2017] [Indexed: 01/05/2023] Open
Abstract
Current models of sensorimotor control posit that motor commands are generated by combining multiple modules which may consist of internal models, motor primitives or motor synergies. The mechanisms which select modules based on task requirements and modify their output during learning are therefore critical to our understanding of sensorimotor control. Here we develop a novel modular architecture for multi-dimensional tasks in which a set of fixed primitives are each able to compensate for errors in a single direction in the task space. The contribution of the primitives to the motor output is determined by both top-down contextual information and bottom-up error information. We implement this model for a task in which subjects learn to manipulate a dynamic object whose orientation can vary. In the model, visual information regarding the context (the orientation of the object) allows the appropriate primitives to be engaged. This top-down module selection is implemented by a Gaussian function tuned for the visual orientation of the object. Second, each module's contribution adapts across trials in proportion to its ability to decrease the current kinematic error. Specifically, adaptation is implemented by cosine tuning of primitives to the current direction of the error, which we show to be theoretically optimal for reducing error. This error-tuned model makes two novel predictions. First, interference should occur between alternating dynamics only when the kinematic errors associated with each oppose one another. In contrast, dynamics which lead to orthogonal errors should not interfere. Second, kinematic errors alone should be sufficient to engage the appropriate modules, even in the absence of contextual information normally provided by vision. We confirm both these predictions experimentally and show that the model can also account for data from previous experiments. Our results suggest that two interacting processes account for module selection during sensorimotor control and learning. Research in motor learning has focused on how we acquire new motor memories for novel situations. However, in many real world motor tasks, the challenge is to select appropriate memories for a given context. In such tasks, we are guided by two key types of information. First, contextual information from vision (for example) is available before we perform the task. Second, movement errors are available as we begin to perform the task. Here we present a model that provides a mechanism by which these two processes operate in parallel to enable us to tune and adapt our motor commands. We show that a model consisting of multiple simple modules, each of which can correct errors in a single direction only, can account for learning in multidimensional tasks. The model makes predictions about which tasks should interfere and how experience of errors alone without any contextual information can drive learning. We confirm these predictions in a series of experiments. The model provides a new framework for understanding the interaction between task context and error feedback during sensorimotor control and learning.
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Affiliation(s)
- James N Ingram
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, United Kingdom
| | - Mohsen Sadeghi
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, United Kingdom
| | - J Randall Flanagan
- Department of Psychology and Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada
| | - Daniel M Wolpert
- Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, United Kingdom
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Lambert-Shirzad N, Van der Loos HFM. Data sample size needed for analysis of kinematic and muscle synergies in healthy and stroke populations. IEEE Int Conf Rehabil Robot 2017; 2017:777-782. [PMID: 28813914 DOI: 10.1109/icorr.2017.8009342] [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: 06/07/2023]
Abstract
Multiple studies have suggested the central nervous system (CNS) generates motions by using modular control of muscles and joints (synergies). However, the synergies reported by these studies are task dependent and might not reflect the true control strategies adopted by the CNS. Studying exploratory motions (EMs) can reveal biomechanical constraints and motor control strategies in healthy and clinical populations. The first logical step to consider EMs in study of motor synergies is to determine how much data is required to reliably and fully profile the motion patterns of an individual. Here we present how the quality of motor synergies analysis depends on the amount of EM data included in the analysis. We recruited 10 healthy and 10 post-stroke participants and collected electromyography (EMG) and joint motion data of their arms as they completed a motor exploration task. We compared the effects of clinical status and limb strength/dominance on the amount of data required to identify synergies. Clinical status had a significant elïect on the required amount of data for both datasets. Limb strength had a significant effect only for kinematic data. We determined the upper bound 95% confidence interval to set the amount of data required for synergy analysis in both populations: 235 sec for EMG data and 265 sec for kinematic data. Our results provide an important step toward using motor exploration in the study of healthy motor synergies and how stroke alters them.
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Ebied A, Spyrou L, Kinney-Lang E, Escudero J. On the use of higher-order tensors to model muscle synergies. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:1792-1795. [PMID: 29060236 DOI: 10.1109/embc.2017.8037192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The muscle synergy concept provides the best framework to understand motor control and it has been recently utilised in many applications such as prosthesis control. The current muscle synergy model relies on decomposing multi-channel surface Electromyography (EMG) signals into a synergy matrix (spatial mode) and its weighting function (temporal mode). This is done using several matrix factorisation techniques, with Non-negative matrix factorisation (NMF) being the most prominent method. Here, we introduce a 4th-order tensor muscle synergy model that extends the current state of the art by taking spectral information and repetitions (movements) into account. This adds more depth to the model and provides more synergistic information. In particular, we illustrate a proof-of-concept study where the Tucker3 tensor decomposition model was applied to a subset of wrist movements from the Ninapro database. The results showed the potential of Tucker3 tensor factorisation in finding patterns of muscle synergies with information about the movements and highlights the differences between the current and proposed model.
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Alexandrov AV, Lippi V, Mergner T, Frolov AA, Hettich G, Husek D. Human-Inspired Eigenmovement Concept Provides Coupling-Free Sensorimotor Control in Humanoid Robot. Front Neurorobot 2017; 11:22. [PMID: 28487646 PMCID: PMC5403929 DOI: 10.3389/fnbot.2017.00022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/04/2017] [Indexed: 12/02/2022] Open
Abstract
Control of a multi-body system in both robots and humans may face the problem of destabilizing dynamic coupling effects arising between linked body segments. The state of the art solutions in robotics are full state feedback controllers. For human hip-ankle coordination, a more parsimonious and theoretically stable alternative to the robotics solution has been suggested in terms of the Eigenmovement (EM) control. Eigenmovements are kinematic synergies designed to describe the multi DoF system, and its control, with a set of independent, and hence coupling-free, scalar equations. This paper investigates whether the EM alternative shows “real-world robustness” against noisy and inaccurate sensors, mechanical non-linearities such as dead zones, and human-like feedback time delays when controlling hip-ankle movements of a balancing humanoid robot. The EM concept and the EM controller are introduced, the robot's dynamics are identified using a biomechanical approach, and robot tests are performed in a human posture control laboratory. The tests show that the EM controller provides stable control of the robot with proactive (“voluntary”) movements and reactive balancing of stance during support surface tilts and translations. Although a preliminary robot-human comparison reveals similarities and differences, we conclude (i) the Eigenmovement concept is a valid candidate when different concepts of human sensorimotor control are considered, and (ii) that human-inspired robot experiments may help to decide in future the choice among the candidates and to improve the design of humanoid robots and robotic rehabilitation devices.
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Affiliation(s)
- Alexei V Alexandrov
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of ScienceMoscow, Russia
| | - Vittorio Lippi
- Department of Neurology, University Clinics of FreiburgFreiburg, Germany
| | - Thomas Mergner
- Department of Neurology, University Clinics of FreiburgFreiburg, Germany
| | - Alexander A Frolov
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of ScienceMoscow, Russia.,Russian National Research Medical UniversityMoscow, Russia
| | - Georg Hettich
- Department of Neurology, University Clinics of FreiburgFreiburg, Germany
| | - Dusan Husek
- Institute of Computer Science, Academy of Science of the Czech RepublicPrague, Czechia
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Moisik SR, Gick B. The Quantal Larynx: The Stable Regions of Laryngeal Biomechanics and Implications for Speech Production. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2017; 60:540-560. [PMID: 28241199 DOI: 10.1044/2016_jslhr-s-16-0019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 08/28/2016] [Indexed: 06/06/2023]
Abstract
PURPOSE Recent proposals suggest that (a) the high dimensionality of speech motor control may be reduced via modular neuromuscular organization that takes advantage of intrinsic biomechanical regions of stability and (b) computational modeling provides a means to study whether and how such modularization works. In this study, the focus is on the larynx, a structure that is fundamental to speech production because of its role in phonation and numerous articulatory functions. METHOD A 3-dimensional model of the larynx was created using the ArtiSynth platform (http://www.artisynth.org). This model was used to simulate laryngeal articulatory states, including inspiration, glottal fricative, modal prephonation, plain glottal stop, vocal-ventricular stop, and aryepiglotto-epiglottal stop and fricative. RESULTS Speech-relevant laryngeal biomechanics is rich with "quantal" or highly stable regions within muscle activation space. CONCLUSIONS Quantal laryngeal biomechanics complement a modular view of speech control and have implications for the articulatory-biomechanical grounding of numerous phonetic and phonological phenomena.
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Affiliation(s)
- Scott Reid Moisik
- Division of Linguistics and Multilingual Studies, Nanyang Technological University, SingaporeThe Max Planck Institute for Psycholinguistics, Nijmegen, the Netherlands
| | - Bryan Gick
- Department of Linguistics, University of British Columbia, Vancouver, CanadaHaskins Laboratories, New Haven, CT
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Lencioni T, Jonsdottir J, Cattaneo D, Crippa A, Gervasoni E, Rovaris M, Bizzi E, Ferrarin M. Are Modular Activations Altered in Lower Limb Muscles of Persons with Multiple Sclerosis during Walking? Evidence from Muscle Synergies and Biomechanical Analysis. Front Hum Neurosci 2016; 10:620. [PMID: 28018193 PMCID: PMC5145858 DOI: 10.3389/fnhum.2016.00620] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 11/21/2016] [Indexed: 12/21/2022] Open
Abstract
Background: Persons with Multiple Sclerosis frequently have gait deficits that lead to diminished activities of daily living. Identification of motoneuron activity patterns may elucidate new insight into impaired locomotor coordination and underlying neural systems. The aim of the present study was to investigate muscle synergies, identified by motor modules and their activation profiles, in persons with Multiple Sclerosis (PwMS) during walking compared to those of healthy subjects (HS), as well as, exploring relationship of muscle synergies with walking ability of PwMS. Methods: Seventeen PwMS walked at their natural speed while 12 HS walked at slower than their natural speeds in order to provide normative gait values at matched speeds (spatio-temporal, kinematic, and kinetic parameters and electromyography signals). Non-negative matrix factorization was used to identify muscle synergies from eight muscles. Pearson's correlation coefficient was used to evaluate the similarity of motor modules between PwMS and HS. To assess differences in module activations, each module's activation timing was integrated over 100% of gait cycle and the activation percentage was computed in six phases. Results: Fifty-nine% of PwMS and 58% of HS had 4 modules while the remaining of both populations had 3 modules. Module 2 (related to soleus, medial, and lateral gastrocnemius primarily involved in mid and terminal stance) and Module 3 (related to tibialis anterior and rectus femoris primarily involved in early stance, and early and late swing) were comparable across all subjects regardless of synergies number. PwMS had shorter stride length, longer double support phase and push off deficit with respect to HS (p < 0.05). The alterations of activation timing profiles of specific modules in PwMS were associated with their walking deficits (e.g., the reduction of Module 2 activation percentage index in terminal stance, PwMS 35.55 ± 13.23 vs. HS 50.51 ± 9.13% p < 0.05, and the push off deficit, PwMS 0.181 ± 0.136 vs. HS 0.291 ± 0.062 w/kg p < 0.05). Conclusion: During gait PwMS have synergies numbers similar to healthy persons. Their neurological deficit alters modular control through modifications of the timing activation profiles rather than module composition. These changes were associated with their main walking impairment, muscle weakness, and prolonged double support.
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Affiliation(s)
- Tiziana Lencioni
- Biomedical Technology Department, IRCCS Fondazione Don Carlo Gnocchi Onlus Milan, Italy
| | - Johanna Jonsdottir
- Department of Neurorehabilitation, IRCCS Fondazione Don Carlo Gnocchi Onlus, LaRiCE Milan, Italy
| | - Davide Cattaneo
- Department of Neurorehabilitation, IRCCS Fondazione Don Carlo Gnocchi Onlus, LaRiCE Milan, Italy
| | - Alessandro Crippa
- Department of Neurorehabilitation, IRCCS Fondazione Don Carlo Gnocchi Onlus, LaRiCE Milan, Italy
| | - Elisa Gervasoni
- Department of Neurorehabilitation, IRCCS Fondazione Don Carlo Gnocchi Onlus, LaRiCE Milan, Italy
| | - Marco Rovaris
- Department of Multiple Sclerosis, IRCCS Fondazione Don Carlo Gnocchi Onlus Milan, Italy
| | - Emilio Bizzi
- Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology Cambridge, MA, USA
| | - Maurizio Ferrarin
- Biomedical Technology Department, IRCCS Fondazione Don Carlo Gnocchi Onlus Milan, Italy
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Gick B. Ecologizing Dimensionality: Prospects for a Modular Theory of Speech Production. ECOLOGICAL PSYCHOLOGY 2016. [DOI: 10.1080/10407413.2016.1195195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Inzelberg R, Plotnik M, Harpaz NK, Flash T. Micrographia, much beyond the writer's hand. Parkinsonism Relat Disord 2016; 26:1-9. [PMID: 26997656 DOI: 10.1016/j.parkreldis.2016.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/12/2016] [Accepted: 03/06/2016] [Indexed: 12/17/2022]
Abstract
INTRODUCTION This review on micrographia aims to draw the clinician's attention to non-Parkinsonian etiologies, provide clues to differential diagnosis, and summarize current knowledge on the phenomenology, etiology, and mechanisms underlying micrographia. METHODS A systematic review of the existing literature was performed. RESULTS Micrographia, namely small sized handwriting has long been attributed to Parkinson's disease. However, it has often been observed as part of the clinical picture of additional neurodegenerative disorders, sometimes antedating the motor signs, or following focal basal ganglia lesions without any accompanying parkinsonism, suggesting that bradykinesia and rigidity are not sine-qua-non for the development of this phenomenon. Therefore, micrographia in a patient with no signs of parkinsonism may prompt the clinician to perform imaging in order to exclude a focal basal ganglia lesion. Dopaminergic etiology in this and other cases is doubtful, since levodopa ameliorates letter stroke size only partially, and only in some patients. Parkinsonian handwriting is often characterized by lack of fluency, slowness, and less frequently by micrographia. Deviations from kinematic laws of motion that govern normal movement, including the lack of movement smoothness and inability to scale movement amplitude to the desired size, may reflect impairments in motion planning, possible loss of automaticity and reduced movement vigor. CONCLUSIONS The etiology, neuroanatomy, mechanisms and models of micrographia are discussed. Dysfunction of the basal ganglia circuitry induced by neurodegeneration or disruption by focal damage give rise to micrographia.
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Affiliation(s)
- Rivka Inzelberg
- Department of Neurology and Neurosurgery, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Tel Hashomer, Israel; Department of Applied Mathematics and Computer Science, The Weizmann Institute of Science, Rehovot, Israel.
| | - Meir Plotnik
- Department of Pharmacology and Physiology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; Center of Advanced Technologies in Rehabilitation, Sheba Medical Center, Tel Hashomer, Israel; Gonda Brain Research Center, Bar Ilan University, Ramat Gan, Israel.
| | - Naama Kadmon Harpaz
- Department of Applied Mathematics and Computer Science, The Weizmann Institute of Science, Rehovot, Israel.
| | - Tamar Flash
- Department of Applied Mathematics and Computer Science, The Weizmann Institute of Science, Rehovot, Israel.
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Collins AGE, Frank MJ. Motor Demands Constrain Cognitive Rule Structures. PLoS Comput Biol 2016; 12:e1004785. [PMID: 26966909 PMCID: PMC4788431 DOI: 10.1371/journal.pcbi.1004785] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
Study of human executive function focuses on our ability to represent cognitive rules independently of stimulus or response modality. However, recent findings suggest that executive functions cannot be modularized separately from perceptual and motor systems, and that they instead scaffold on top of motor action selection. Here we investigate whether patterns of motor demands influence how participants choose to implement abstract rule structures. In a learning task that requires integrating two stimulus dimensions for determining appropriate responses, subjects typically structure the problem hierarchically, using one dimension to cue the task-set and the other to cue the response given the task-set. However, the choice of which dimension to use at each level can be arbitrary. We hypothesized that the specific structure subjects adopt would be constrained by the motor patterns afforded within each rule. Across four independent data-sets, we show that subjects create rule structures that afford motor clustering, preferring structures in which adjacent motor actions are valid within each task-set. In a fifth data-set using instructed rules, this bias was strong enough to counteract the well-known task switch-cost when instructions were incongruent with motor clustering. Computational simulations confirm that observed biases can be explained by leveraging overlap in cortical motor representations to improve outcome prediction and hence infer the structure to be learned. These results highlight the importance of sensorimotor constraints in abstract rule formation and shed light on why humans have strong biases to invent structure even when it does not exist.
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Affiliation(s)
- Anne Gabrielle Eva Collins
- Department of Cognitive, Linguistic and Psychological Sciences, Brown Institute for Brain Science, Brown University, Providence, Rhode Island, United States of America
- Department of Psychology, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
| | - Michael Joshua Frank
- Department of Cognitive, Linguistic and Psychological Sciences, Brown Institute for Brain Science, Brown University, Providence, Rhode Island, United States of America
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