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Abbott EM, Stephens JD, Simha SN, Wood L, Nardelli P, Cope TC, Sawicki GS, Ting LH. Attenuation of muscle spindle firing with artificially increased series compliance during stretch of relaxed muscle. Exp Physiol 2024; 109:148-158. [PMID: 37856330 PMCID: PMC10841431 DOI: 10.1113/ep090872] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 09/15/2023] [Indexed: 10/21/2023]
Abstract
Muscle spindles relay vital mechanosensory information for movement and posture, but muscle spindle feedback is coupled to skeletal motion by a compliant tendon. Little is known about the effects of tendon compliance on muscle spindle feedback during movement, and the complex firing of muscle spindles makes these effects difficult to predict. Our goal was to investigate changes in muscle spindle firing using added series elastic elements (SEEs) to mimic a more compliant tendon, and to characterize the accompanying changes in firing with respect to muscle-tendon unit (MTU) and muscle fascicle displacements (recorded via sonomicrometry). Sinusoidal, ramp-and-hold and triangular stretches were analysed to examine potential changes in muscle spindle instantaneous firing rates (IFRs) in locomotor- and perturbation-like stretches as well as serial history dependence. Added SEEs effectively reduced overall MTU stiffness and generally reduced muscle spindle firing rates, but the effect differed across stretch types. During sinusoidal stretches, peak and mean firing rates were not reduced and IFR was best-correlated with fascicle velocity. During ramp stretches, SEEs reduced the initial burst, dynamic and static responses of the spindle. Notably, IFR was negatively related to fascicle displacement during the hold phase. During triangular stretches, SEEs reduced the mean IFR during the first and second stretches, affecting the serial history dependence of mean IFR. Overall, these results demonstrate that tendon compliance may attenuate muscle spindle feedback during movement, but these changes cannot be fully explained by reduced muscle fascicle length or velocity, or MTU force.
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Affiliation(s)
- Emily M. Abbott
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
| | - Jacob D. Stephens
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Surabhi N. Simha
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Leo Wood
- School of PhysicsGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Timothy C. Cope
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Gregory S. Sawicki
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGeorgiaUSA
- Woodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Lena H. Ting
- Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
- Department of Rehabilitation MedicineEmory UniversityAtlantaGeorgiaUSA
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2
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Abbott EM, Stephens JD, Simha SN, Wood L, Nardelli P, Cope TC, Sawicki GS, Ting LH. Attenuation of muscle spindle firing with artificially increased series compliance during stretch of relaxed muscle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539853. [PMID: 37215007 PMCID: PMC10197546 DOI: 10.1101/2023.05.08.539853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Muscle spindles relay vital mechanosensory information for movement and posture, but muscle spindle feedback is coupled to skeletal motion by a compliant tendon. Little is known about the effects of tendon compliance on muscle spindle feedback during movement, and the complex firing of muscle spindles make these effects difficult to predict. Our goal was to investigate changes in muscle spindle firing using added series elastic elements (SEEs) to mimic a more compliant tendon, and to characterize the accompanying changes in firing with respect to muscle-tendon unit (MTU) and muscle fascicle displacements (recorded via sonomicrometry). Sinusoidal, ramp-hold-release, and triangular stretches were analyzed to examine potential changes in muscle spindle instantaneous firing rates (IFRs) in locomotor- and perturbation-like stretches as well as history dependence. Added SEEs effectively reduced overall MTU stiffness and generally reduced muscle spindle firing rates, but the effect differed across stretch types. During sinusoidal stretches, peak firing rates were reduced and IFR was strongly correlated with fascicle velocity. During ramp stretches, SEEs reduced the dynamic and static responses of the spindle during lengthening but had no effect on initial bursts at the onset of stretch. Notably, IFR was negatively related to fascicle displacement during the hold phase. During triangular stretches, SEEs reduced the mean IFR during the first and second stretches, affecting the history dependence of mean IFR. Overall, these results demonstrate that tendon compliance may attenuate muscle spindle feedback during movement, but these changes cannot be fully explained by reduced muscle fascicle length and velocity.
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Affiliation(s)
| | - Jacob D Stephens
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
| | - Surabhi N Simha
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
| | - Leo Wood
- School of Physics, Georgia Institute of Technology
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology
| | - Timothy C Cope
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- School of Biological Sciences, Georgia Institute of Technology
| | - Gregory S Sawicki
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology
| | - Lena H Ting
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology
- Department of Rehabilitation Medicine, Emory University
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Abstract
When animals walk overground, mechanical stimuli activate various receptors located in muscles, joints, and skin. Afferents from these mechanoreceptors project to neuronal networks controlling locomotion in the spinal cord and brain. The dynamic interactions between the control systems at different levels of the neuraxis ensure that locomotion adjusts to its environment and meets task demands. In this article, we describe and discuss the essential contribution of somatosensory feedback to locomotion. We start with a discussion of how biomechanical properties of the body affect somatosensory feedback. We follow with the different types of mechanoreceptors and somatosensory afferents and their activity during locomotion. We then describe central projections to locomotor networks and the modulation of somatosensory feedback during locomotion and its mechanisms. We then discuss experimental approaches and animal models used to investigate the control of locomotion by somatosensory feedback before providing an overview of the different functional roles of somatosensory feedback for locomotion. Lastly, we briefly describe the role of somatosensory feedback in the recovery of locomotion after neurological injury. We highlight the fact that somatosensory feedback is an essential component of a highly integrated system for locomotor control. © 2021 American Physiological Society. Compr Physiol 11:1-71, 2021.
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Affiliation(s)
- Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Quebec, Canada
| | - Turgay Akay
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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Parametric control of limb mechanics is accomplished in the spinal cord by parallel-distributed processing: A commentary on the review "Laws of nature that define biological action and perception" by Mark L. Latash. Phys Life Rev 2021; 37:94-96. [PMID: 33774430 DOI: 10.1016/j.plrev.2021.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 03/15/2021] [Indexed: 11/23/2022]
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Blum KP, Campbell KS, Horslen BC, Nardelli P, Housley SN, Cope TC, Ting LH. Diverse and complex muscle spindle afferent firing properties emerge from multiscale muscle mechanics. eLife 2020; 9:e55177. [PMID: 33370235 PMCID: PMC7769569 DOI: 10.7554/elife.55177] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 12/04/2020] [Indexed: 11/13/2022] Open
Abstract
Despite decades of research, we lack a mechanistic framework capable of predicting how movement-related signals are transformed into the diversity of muscle spindle afferent firing patterns observed experimentally, particularly in naturalistic behaviors. Here, a biophysical model demonstrates that well-known firing characteristics of mammalian muscle spindle Ia afferents - including movement history dependence, and nonlinear scaling with muscle stretch velocity - emerge from first principles of muscle contractile mechanics. Further, mechanical interactions of the muscle spindle with muscle-tendon dynamics reveal how motor commands to the muscle (alpha drive) versus muscle spindle (gamma drive) can cause highly variable and complex activity during active muscle contraction and muscle stretch that defy simple explanation. Depending on the neuromechanical conditions, the muscle spindle model output appears to 'encode' aspects of muscle force, yank, length, stiffness, velocity, and/or acceleration, providing an extendable, multiscale, biophysical framework for understanding and predicting proprioceptive sensory signals in health and disease.
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Affiliation(s)
- Kyle P Blum
- Department of Physiology, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | | | - Brian C Horslen
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Stephen N Housley
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Timothy C Cope
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Lena H Ting
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- Department of Rehabilitation Medicine, Emory UniversityAtlantaUnited States
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Blum KP, Nardelli P, Cope TC, Ting LH. Elastic tissue forces mask muscle fiber forces underlying muscle spindle Ia afferent firing rates in stretch of relaxed rat muscle. J Exp Biol 2019; 222:jeb196287. [PMID: 31324662 PMCID: PMC6703702 DOI: 10.1242/jeb.196287] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 07/12/2019] [Indexed: 11/20/2022]
Abstract
Stretches of relaxed cat and rat muscle elicit similar history-dependent muscle spindle Ia firing rates that resemble history-dependent forces seen in single activated muscle fibers ( Nichols and Cope, 2004). Owing to thixotropy, whole musculotendon forces and muscle spindle firing rates are history dependent during stretch of relaxed cat muscle, where both muscle force and muscle spindle firing rates are elevated in the first stretch in a series of stretch-shorten cycles ( Blum et al., 2017). By contrast, rat musculotendon exhibits only mild thixotropy, such that the measured forces when stretched cannot explain history-dependent muscle spindle firing rates in the same way ( Haftel et al., 2004). We hypothesized that history-dependent muscle spindle firing rates elicited in stretch of relaxed rat muscle mirror history-dependent muscle fiber forces, which are masked at the level of whole musculotendon force by extracellular tissue force. We removed estimated extracellular tissue force contributions from recorded musculotendon force using an exponentially elastic tissue model. We then showed that the remaining estimated muscle fiber force resembles history-dependent muscle spindle firing rates recorded simultaneously. These forces also resemble history-dependent forces recorded in stretch of single activated fibers that are attributed to muscle cross-bridge mechanisms ( Campbell and Moss, 2000). Our results suggest that history-dependent muscle spindle firing in both rats and cats arise from history-dependent forces owing to thixotropy in muscle fibers.
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Affiliation(s)
- Kyle P Blum
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Timothy C Cope
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, GA 30322, USA
| | - Lena H Ting
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, GA 30322, USA
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Lee LA, Karabina A, Broadwell LJ, Leinwand LA. The ancient sarcomeric myosins found in specialized muscles. Skelet Muscle 2019; 9:7. [PMID: 30836986 PMCID: PMC6402096 DOI: 10.1186/s13395-019-0192-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 02/22/2019] [Indexed: 12/17/2022] Open
Abstract
Striated muscles express an array of sarcomeric myosin motors that are tuned to accomplish specific tasks. Each myosin isoform found in muscle fibers confers unique contractile properties to the fiber in order to meet the demands of the muscle. The sarcomeric myosin heavy chain (MYH) genes expressed in the major cardiac and skeletal muscles have been studied for decades. However, three ancient myosins, MYH7b, MYH15, and MYH16, remained uncharacterized due to their unique expression patterns in common mammalian model organisms and due to their relatively recent discovery in these genomes. This article reviews the literature surrounding these three ancient sarcomeric myosins and the specialized muscles in which they are expressed. Further study of these ancient myosins and how they contribute to the functions of the specialized muscles may provide novel insight into the history of striated muscle evolution.
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Affiliation(s)
- Lindsey A. Lee
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO USA
- BioFrontiers Institute, University of Colorado, Boulder, CO USA
| | - Anastasia Karabina
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO USA
- BioFrontiers Institute, University of Colorado, Boulder, CO USA
| | - Lindsey J. Broadwell
- BioFrontiers Institute, University of Colorado, Boulder, CO USA
- Department of Biochemistry, University of Colorado, Boulder, CO USA
| | - Leslie A. Leinwand
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO USA
- BioFrontiers Institute, University of Colorado, Boulder, CO USA
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Blum KP, Lamotte D’Incamps B, Zytnicki D, Ting LH. Force encoding in muscle spindles during stretch of passive muscle. PLoS Comput Biol 2017; 13:e1005767. [PMID: 28945740 PMCID: PMC5634630 DOI: 10.1371/journal.pcbi.1005767] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/10/2017] [Accepted: 09/05/2017] [Indexed: 12/03/2022] Open
Abstract
Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions relevant to the detection and sensorimotor response to mechanical perturbations to the body, and to previously-described history-dependence in perception of limb position.
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Affiliation(s)
- Kyle P. Blum
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Boris Lamotte D’Incamps
- Center for Neurophysics, Physiology and Pathophysiology, Université Paris Descartes, Paris, France
| | - Daniel Zytnicki
- Center for Neurophysics, Physiology and Pathophysiology, Université Paris Descartes, Paris, France
| | - Lena H. Ting
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia, United States of America
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, Georgia, United States of America
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9
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Smilde HA, Vincent JA, Baan GC, Nardelli P, Lodder JC, Mansvelder HD, Cope TC, Maas H. Changes in muscle spindle firing in response to length changes of neighboring muscles. J Neurophysiol 2016; 115:3146-55. [PMID: 27075540 DOI: 10.1152/jn.00937.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 04/05/2016] [Indexed: 01/03/2023] Open
Abstract
Skeletal muscle force can be transmitted to the skeleton, not only via its tendons of origin and insertion but also through connective tissues linking the muscle belly to surrounding structures. Through such epimuscular myofascial connections, length changes of a muscle may cause length changes within an adjacent muscle and hence, affect muscle spindles. The aim of the present study was to investigate the effects of epimuscular myofascial forces on feedback from muscle spindles in triceps surae muscles of the rat. We hypothesized that within an intact muscle compartment, muscle spindles not only signal length changes of the muscle in which they are located but can also sense length changes that occur as a result of changing the length of synergistic muscles. Action potentials from single afferents were measured intra-axonally in response to ramp-hold release (RHR) stretches of an agonistic muscle at different lengths of its synergist, as well as in response to synergist RHRs. A decrease in force threshold was found for both soleus (SO) and lateral gastrocnemius afferents, along with an increase in length threshold for SO afferents. In addition, muscle spindle firing could be evoked by RHRs of the synergistic muscle. We conclude that muscle spindles not only signal length changes of the muscle in which they are located but also local length changes that occur as a result of changing the length and relative position of synergistic muscles.
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Affiliation(s)
- Hiltsje A Smilde
- Department of Human Movement Sciences, MOVE Research Institute Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, Ohio
| | - Jake A Vincent
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, Ohio
| | - Guus C Baan
- Department of Human Movement Sciences, MOVE Research Institute Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Paul Nardelli
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, Ohio; School of Applied Physiology and Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Johannes C Lodder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Tim C Cope
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, Ohio; School of Applied Physiology and Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Huub Maas
- Department of Human Movement Sciences, MOVE Research Institute Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands;
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Nichols TR, Bunderson NE, Lyle MA. Neural Regulation of Limb Mechanics: Insights from the Organization of Proprioceptive Circuits. NEUROMECHANICAL MODELING OF POSTURE AND LOCOMOTION 2016. [DOI: 10.1007/978-1-4939-3267-2_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Franco JA, Kloefkorn HE, Hochman S, Wilkinson KA. An in vitro adult mouse muscle-nerve preparation for studying the firing properties of muscle afferents. J Vis Exp 2014:51948. [PMID: 25285602 PMCID: PMC4618553 DOI: 10.3791/51948] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Muscle sensory neurons innervating muscle spindles and Golgi tendon organs encode length and force changes essential to proprioception. Additional afferent fibers monitor other characteristics of the muscle environment, including metabolite buildup, temperature, and nociceptive stimuli. Overall, abnormal activation of sensory neurons can lead to movement disorders or chronic pain syndromes. We describe the isolation of the extensor digitorum longus (EDL) muscle and nerve for in vitro study of stretch-evoked afferent responses in the adult mouse. Sensory activity is recorded from the nerve with a suction electrode and individual afferents can be analyzed using spike sorting software. In vitro preparations allow for well controlled studies on sensory afferents without the potential confounds of anesthesia or altered muscle perfusion. Here we describe a protocol to identify and test the response of muscle spindle afferents to stretch. Importantly, this preparation also supports the study of other subtypes of muscle afferents, response properties following drug application and the incorporation of powerful genetic approaches and disease models in mice.
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Affiliation(s)
- Joy A Franco
- Department of Mechanical Engineering, San José State University
| | - Heidi E Kloefkorn
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida
| | - Shawn Hochman
- Department of Physiology, Emory University School of Medicine
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Nishikawa KC, Monroy JA, Powers KL, Gilmore LA, Uyeno TA, Lindstedt SL. A Molecular Basis for Intrinsic Muscle Properties: Implications for Motor Control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 782:111-25. [DOI: 10.1007/978-1-4614-5465-6_6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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13
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Safavynia SA, Ting LH. Sensorimotor feedback based on task-relevant error robustly predicts temporal recruitment and multidirectional tuning of muscle synergies. J Neurophysiol 2012; 109:31-45. [PMID: 23100133 DOI: 10.1152/jn.00684.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We hypothesized that motor outputs are hierarchically organized such that descending temporal commands based on desired task-level goals flexibly recruit muscle synergies that specify the spatial patterns of muscle coordination that allow the task to be achieved. According to this hypothesis, it should be possible to predict the patterns of muscle synergy recruitment based on task-level goals. We demonstrated that the temporal recruitment of muscle synergies during standing balance control was robustly predicted across multiple perturbation directions based on delayed sensorimotor feedback of center of mass (CoM) kinematics (displacement, velocity, and acceleration). The modulation of a muscle synergy's recruitment amplitude across perturbation directions was predicted by the projection of CoM kinematic variables along the preferred tuning direction(s), generating cosine tuning functions. Moreover, these findings were robust in biphasic perturbations that initially imposed a perturbation in the sagittal plane and then, before sagittal balance was recovered, perturbed the body in multiple directions. Therefore, biphasic perturbations caused the initial state of the CoM to differ from the desired state, and muscle synergy recruitment was predicted based on the error between the actual and desired upright state of the CoM. These results demonstrate that that temporal motor commands to muscle synergies reflect task-relevant error as opposed to sensory inflow. The proposed hierarchical framework may represent a common principle of motor control across motor tasks and levels of the nervous system, allowing motor intentions to be transformed into motor actions.
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Affiliation(s)
- Seyed A Safavynia
- Neuroscience Program, Emory University, Atlanta, Georgia 30332-0535, USA
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14
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The implications of force feedback for the lambda model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 629:663-79. [PMID: 19227527 DOI: 10.1007/978-0-387-77064-2_36] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
It is argued here that length and force feedback play important but distinct roles in motor coordination. Length feedback compensates for several nonlinear properties of muscle and therefore simplifies its behavior, but in addition promotes the nonlinear relationship between force and stiffness that is essential to the mechanism for modulating joint stiffness. Excitatory force feedback is also primarily autogenic. Under conditions of level treadmill stepping in cat walking, positive force feedback is restricted in the distal hindlimb to a few and perhaps only one ankle extensor, the gastrocnemius muscle group. Based on the anatomy of this group, positive force feedback provides a stiff linkage that reinforces proportional coordination between ankle and knee joints. In terms of the lambda model, excitatory force feedback can reinforce muscular force generation and stiffness, but should have no significant effect on activation threshold. Inhibitory force feedback projects mainly to muscles that span different joints and axes of rotation than the parent muscle. This heterogenic force feedback is thought to promote interjoint coordination and thought to influence stiffness of the joints and limbs. During locomotion, the inhibitory influences appear to be focused on the distal musculature. Since the inhibitory force feedback is heterogenic, it also influences the threshold for activation of relevant musculature. Threshold is therefore not entirely a control variable and independent of feedback. It is proposed that the actuators for movement consist of systems of muscles or motor units that are linked by feedback and that receive control signals from elsewhere in the nervous system.
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15
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Nieuwenhuijzen PHJA, Duysens J. Proactive and Reactive Mechanisms Play a Role in Stepping on Inverting Surfaces During Gait. J Neurophysiol 2007; 98:2266-73. [PMID: 17715190 DOI: 10.1152/jn.01226.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ankle inversions have been studied extensively during standing conditions. However, inversion traumas occur during more dynamic conditions, like walking. Therefore in this study sudden ankle inversions were elicited in 12 healthy subjects who stepped on a trap door while walking on a treadmill. First, 10 control trials (0° of rotation) were presented. Then, 20 stimulus (25° of rotation) and control trials were presented randomly. EMG recordings were made of six lower leg muscles. All muscles showed a short-latency response (SLR) of about 40 ms and a late-latency response (LLR) of about 90 ms. The peroneal muscles showed the largest amplitudes in both responses. The functionally more important, larger, and more consistent LLR response was too late to resist the induced stretch during the inversion. The functional relevance of this response must lie after the inversion. During the first trial a widespread “startle-like” coactivation of the LLR was observed. The last trials showed only a recruitment of the peroneal muscles and, to a lesser extent, the gastrocnemius lateralis, which is seen as a switch from reactive control to more proactive adaptive strategies. These proactive strategies were investigated separately by comparing trials in which inversion was expected (but did not occur) with those in which subjects knew that no inversion would occur. Anticipation of a possible inversion was expressed in decreased tibialis anterior activity before initial contact, consistent with a more cautious and stable foot placement. Furthermore, immediately after landing, the peroneal muscles were activated to counteract the upcoming stretch.
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Affiliation(s)
- P H J A Nieuwenhuijzen
- Department of Rehabilitation Medicine, Radboud University Nijmegen Medical Center, 6500 HB, Nijmegen, The Netherlands
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16
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Mileusnic MP, Brown IE, Lan N, Loeb GE. Mathematical models of proprioceptors. I. Control and transduction in the muscle spindle. J Neurophysiol 2006; 96:1772-88. [PMID: 16672301 DOI: 10.1152/jn.00868.2005] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We constructed a physiologically realistic model of a lower-limb, mammalian muscle spindle composed of mathematical elements closely related to the anatomical components found in the biological spindle. The spindle model incorporates three nonlinear intrafusal fiber models (bag(1), bag(2), and chain) that contribute variously to action potential generation of primary and secondary afferents. A single set of model parameters was optimized on a number of data sets collected from feline soleus muscle, accounting accurately for afferent activity during a variety of ramp, triangular, and sinusoidal stretches. We also incorporated the different temporal properties of fusimotor activation as observed in the twitchlike chain fibers versus the toniclike bag fibers. The model captures the spindle's behavior both in the absence of fusimotor stimulation and during activation of static or dynamic fusimotor efferents. In the case of simultaneous static and dynamic fusimotor efferent stimulation, we demonstrated the importance of including the experimentally observed effect of partial occlusion. The model was validated against data that originated from the cat's medial gastrocnemius muscle and were different from the data used for the parameter determination purposes. The validation record included recently published experiments in which fusimotor efferent and spindle afferent activities were recorded simultaneously during decerebrate locomotion in the cat. This model will be useful in understanding the role of the muscle spindle and its fusimotor control during both natural and pathological motor behavior.
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Affiliation(s)
- Milana P Mileusnic
- Department of Biomedical Engineering, Alfred E. Mann Institute for Biomedical Engineering, University of Southern California, Los Angeles, CA 90089-1112, USA.
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Smits-Engelsman BCM, Swinnen SP, Duysens J. The advantage of cyclic over discrete movements remains evident following changes in load and amplitude. Neurosci Lett 2006; 396:28-32. [PMID: 16326008 DOI: 10.1016/j.neulet.2005.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 10/27/2005] [Accepted: 11/02/2005] [Indexed: 10/25/2022]
Abstract
Previous studies suggested that the advantage in speed accuracy trade-off of cyclic over discrete aiming tasks with the upper limbs may be associated with the operation of spinal neural oscillators, as in locomotion. Similar to the locomotor rhythm that is fairly robust and can accommodate changes in loading or stride length, we predicted that cyclic aiming tasks would be equally resistant to changes in load or amplitude, thereby preserving the advantage over discrete tasks. To test the hypothesis, cyclic and discrete aiming movements were performed with and without loading of the hand. Furthermore a "complex" condition was introduced in which the distance between the targets that the participants moved to alternated between 2.5 and 5 cm. In all cases, two target sizes were used to test spatial accuracy and to be able to calculate the Index of Performance (IP). Findings revealed that even though part of the advantage of the cyclic over the discrete regime was lost during the complex movement pattern and with addition of weight, the former remained superior to the latter. Furthermore, adding weight did not change the oscillation frequency in the cyclic movements. It is concluded that the superiority of cyclic movements over discrete ones is fairly robust, consistent with the high degree of flexibility that is typically observed in neural oscillators.
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Affiliation(s)
- B C M Smits-Engelsman
- Motor Control Lab, Department of Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, K.U.Leuven, Tervuurse Vest 101, 3001 B-Leuven, Belgium.
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