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Zhou C, Zhu L, Liu Z, Tong Y, Xu Y, Jiang L, Li X. Whole body vibration training promotes proprioceptive pathway for the treatment of stress urinary incontinence in rats. Transl Androl Urol 2024; 13:657-666. [PMID: 38855607 PMCID: PMC11157409 DOI: 10.21037/tau-23-675] [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: 12/25/2023] [Accepted: 03/31/2024] [Indexed: 06/11/2024] Open
Abstract
Background Stress urinary incontinence (SUI) is the most ubiquitous form of urinary incontinence in women. The therapeutic management of patients with SUI is challenging. The aim of this study is to evaluate the efficacy of whole body vibration training (WBVT) for SUI. Methods Thirty-five female rats were randomly divided into a sham group (Sham group, n=5), SUI + WBVT group (n=15) and SUI + whole body rest group (SUI + WBR group, n=15). The SUI + WBVT group was trained as follows: frequency 30 Hz, amplitude four mm, one min/repeat, four min rest, repeated 10 times, five days/week. After the intervention, five rats were taken on the 7th, 14th and 21st day to observe the urodynamic changes, levator ani muscle and dorsal root ganglia (DRG) morphology, and to observe the expression of neurotrophic factor-3/tyrosine protein kinase C (NT-3/TrkC) by Western blot. Results The urodynamic results showed that the difference in bladder leak point pressure/abdominal leak point pressure (BLPP/ALPP) between the Sham group and the SUI + WBR group was statistically significant (P<0.001) on 7th day, indicating successful modeling. The BLPP/ALPP of the SUI + WBVT group and the SUI + WBR group improved on 7th, 14th, and 21st day, and the BLPP/ALPP of SUI + WBVT group was higher than the SUI + WBR group. Compared with the Sham group, pathological changes appeared in the muscle shuttles in the SUI + WBVT group and SUI + WBR group. Western blot showed a gradual up-regulation of NT-3/TrkC. Conclusions WBVT can be used to treat SUI by affecting the expression of NT-3/TrkC, improving the structural morphology of the proprioceptors, and restoring the urinary control function. This study provides evidence for the clinical practice of WBVT. Future studies could further refine the behavioral and electrophysiological aspects of the assessment.
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Affiliation(s)
- Chengyu Zhou
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Liping Zhu
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Zhaoxue Liu
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Yao Tong
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Yuting Xu
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Li Jiang
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
- Postdoctoral Research Station of Basic Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
| | - Xuhong Li
- Department of Rehabilitation Medicine, The 3rd Xiangya Hospital, Central South University, Changsha, China
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2
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Gradwell MA, Ozeri-Engelhard N, Eisdorfer JT, Laflamme OD, Gonzalez M, Upadhyay A, Medlock L, Shrier T, Patel KR, Aoki A, Gandhi M, Abbas-Zadeh G, Oputa O, Thackray JK, Ricci M, George A, Yusuf N, Keating J, Imtiaz Z, Alomary SA, Bohic M, Haas M, Hernandez Y, Prescott SA, Akay T, Abraira VE. Multimodal sensory control of motor performance by glycinergic interneurons of the mouse spinal cord deep dorsal horn. Neuron 2024; 112:1302-1327.e13. [PMID: 38452762 DOI: 10.1016/j.neuron.2024.01.027] [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: 06/13/2023] [Revised: 10/31/2023] [Accepted: 01/26/2024] [Indexed: 03/09/2024]
Abstract
Sensory feedback is integral for contextually appropriate motor output, yet the neural circuits responsible remain elusive. Here, we pinpoint the medial deep dorsal horn of the mouse spinal cord as a convergence point for proprioceptive and cutaneous input. Within this region, we identify a population of tonically active glycinergic inhibitory neurons expressing parvalbumin. Using anatomy and electrophysiology, we demonstrate that deep dorsal horn parvalbumin-expressing interneuron (dPV) activity is shaped by convergent proprioceptive, cutaneous, and descending input. Selectively targeting spinal dPVs, we reveal their widespread ipsilateral inhibition onto pre-motor and motor networks and demonstrate their role in gating sensory-evoked muscle activity using electromyography (EMG) recordings. dPV ablation altered limb kinematics and step-cycle timing during treadmill locomotion and reduced the transitions between sub-movements during spontaneous behavior. These findings reveal a circuit basis by which sensory convergence onto dorsal horn inhibitory neurons modulates motor output to facilitate smooth movement and context-appropriate transitions.
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Affiliation(s)
- Mark A Gradwell
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Nofar Ozeri-Engelhard
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; Neuroscience PhD program, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Jaclyn T Eisdorfer
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Olivier D Laflamme
- Dalhousie PhD program, Dalhousie University, Halifax, NS, Canada; Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, NS, Canada
| | - Melissa Gonzalez
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; Department of Biomedical Engineering, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Aman Upadhyay
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; Neuroscience PhD program, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Laura Medlock
- Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Tara Shrier
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Komal R Patel
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Adin Aoki
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Melissa Gandhi
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Gloria Abbas-Zadeh
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Olisemaka Oputa
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Joshua K Thackray
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; Human Genetics Institute of New Jersey, Rutgers University, The State University of New Jersey, Piscataway, NJ, USA; Tourette International Collaborative Genetics Study (TIC Genetics)
| | - Matthew Ricci
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Arlene George
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Nusrath Yusuf
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; Neuroscience PhD program, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Jessica Keating
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Zarghona Imtiaz
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Simona A Alomary
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Manon Bohic
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Michael Haas
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Yurdiana Hernandez
- W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA
| | - Steven A Prescott
- Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Turgay Akay
- Department of Medical Neuroscience, Atlantic Mobility Action Project, Brain Repair Center, Dalhousie University, Halifax, NS, Canada
| | - Victoria E Abraira
- Cell Biology and Neuroscience Department, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA; W.M. Keck Center for Collaborative Neuroscience, Rutgers University, The State University of New Jersey, New Brunswick, NJ, USA.
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3
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Housley SN, Gardolinski EA, Nardelli P, Reed J, Rich MM, Cope TC. Mechanosensory encoding in ex vivo muscle-nerve preparations. Exp Physiol 2024; 109:35-44. [PMID: 37119460 PMCID: PMC10613129 DOI: 10.1113/ep090763] [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: 12/23/2022] [Accepted: 04/12/2023] [Indexed: 05/01/2023]
Abstract
Our objective was to evaluate an ex vivo muscle-nerve preparation used to study mechanosensory signalling by low threshold mechanosensory receptors (LTMRs). Specifically, we aimed to assess how well the ex vivo preparation represents in vivo firing behaviours of the three major LTMR subtypes of muscle primary sensory afferents, namely type Ia and II muscle spindle (MS) afferents and type Ib tendon organ afferents. Using published procedures for ex vivo study of LTMRs in mouse hindlimb muscles, we replicated earlier reports on afferent firing in response to conventional stretch paradigms applied to non-contracting, that is passive, muscle. Relative to in vivo studies, stretch-evoked firing for confirmed MS afferents in the ex vivo preparation was markedly reduced in firing rate and deficient in encoding dynamic features of muscle stretch. These deficiencies precluded conventional means of discriminating type Ia and II afferents. Muscle afferents, including confirmed Ib afferents were often indistinguishable based on their similar firing responses to the same physiologically relevant stretch paradigms. These observations raise uncertainty about conclusions drawn from earlier ex vivo studies that either attribute findings to specific afferent types or suggest an absence of treatment effects on dynamic firing. However, we found that replacing the recording solution with bicarbonate buffer resulted in afferent firing rates and profiles more like those seen in vivo. Improving representation of the distinctive sensory encoding properties in ex vivo muscle-nerve preparations will promote accuracy in assigning molecular markers and mechanisms to heterogeneous types of muscle mechanosensory neurons.
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Affiliation(s)
- Stephen N. Housley
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | | | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - J'Ana Reed
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
| | - Mark M. Rich
- Department of Neuroscience, Cell Biology and PhysiologyWright State UniversityDaytonOHUSA
| | - Timothy C. Cope
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGAUSA
- W.H. Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of Technology, Georgia Institute of TechnologyAtlantaGAUSA
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4
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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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5
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Housley SN, Powers RK, Nardelli P, Lee S, Blum K, Bewick GS, Banks RW, Cope TC. Biophysical model of muscle spindle encoding. Exp Physiol 2024; 109:55-65. [PMID: 36966478 PMCID: PMC10988694 DOI: 10.1113/ep091099] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/09/2023] [Indexed: 03/27/2023]
Abstract
Muscle spindles encode mechanosensory information by mechanisms that remain only partially understood. Their complexity is expressed in mounting evidence of various molecular mechanisms that play essential roles in muscle mechanics, mechanotransduction and intrinsic modulation of muscle spindle firing behaviour. Biophysical modelling provides a tractable approach to achieve more comprehensive mechanistic understanding of such complex systems that would be difficult/impossible by more traditional, reductionist means. Our objective here was to construct the first integrative biophysical model of muscle spindle firing. We leveraged current knowledge of muscle spindle neuroanatomy and in vivo electrophysiology to develop and validate a biophysical model that reproduces key in vivo muscle spindle encoding characteristics. Crucially, to our knowledge, this is the first computational model of mammalian muscle spindle that integrates the asymmetric distribution of known voltage-gated ion channels (VGCs) with neuronal architecture to generate realistic firing profiles, both of which seem likely to be of great biophysical importance. Results predict that particular features of neuronal architecture regulate specific characteristics of Ia encoding. Computational simulations also predict that the asymmetric distribution and ratios of VGCs is a complementary and, in some instances, orthogonal means to regulate Ia encoding. These results generate testable hypotheses and highlight the integral role of peripheral neuronal structure and ion channel composition and distribution in somatosensory signalling.
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Affiliation(s)
| | - Randal K. Powers
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Paul Nardelli
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGA
| | - Sebinne Lee
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGA
| | - Kyle Blum
- Department of Physiology, Feinberg School of MedicineNorthwestern UniversityChicagoILUSA
| | - Guy S. Bewick
- Institute of Medical ScienceUniversity of AberdeenAberdeenUK
| | | | - Timothy C. Cope
- School of Biological SciencesGeorgia Institute of TechnologyAtlantaGA
- W. H. Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of Technology, Georgia Institute of TechnologyAtlantaGA
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6
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de Nooij JC, Zampieri N. The making of a proprioceptor: a tale of two identities. Trends Neurosci 2023; 46:1083-1094. [PMID: 37858440 DOI: 10.1016/j.tins.2023.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/21/2023]
Abstract
Proprioception, the sense of body position in space, has a critical role in the control of posture and movement. Aside from skin and joint receptors, the main sources of proprioceptive information in tetrapods are mechanoreceptive end organs in skeletal muscle: muscle spindles (MSs) and Golgi tendon organs (GTOs). The sensory neurons that innervate these receptors are divided into subtypes that detect discrete aspects of sensory information from muscles with different biomechanical functions. Despite the importance of proprioceptive neurons in motor control, the developmental mechanisms that control the acquisition of their distinct functional properties and positional identity are not yet clear. In this review, we discuss recent findings on the development of mouse proprioceptor subtypes and challenges in defining them at the molecular and functional level.
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Affiliation(s)
- Joriene C de Nooij
- Department of Neurology, Division of Translational Neurobiology, Vagelos College of Physicians and Surgeons, 650 West 168th Street, New York, NY 10032, USA; Columbia University Motor Neuron Center, Columbia University Medical Center, 630 West 168th Street, New York, NY 10032, USA.
| | - Niccolò Zampieri
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
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7
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de Nooij JC. Engineering mechanoreceptor feature selectivity. Neuron 2023; 111:3137-3139. [PMID: 37857088 DOI: 10.1016/j.neuron.2023.09.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 09/26/2023] [Accepted: 09/26/2023] [Indexed: 10/21/2023]
Abstract
Touch and proprioception rely on the discriminative abilities of distinct classes of mechanosensory neurons. In this issue of Neuron, two studies1,2 provide evidence that biomechanical mechanisms and ultrastructural cellular specializations are key contributors in defining mechanoreceptor stimulus threshold and selectivity.
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Affiliation(s)
- Joriene C de Nooij
- Department of Neurology and Columbia University Motor Neuron Center, Columbia University Irving Medical Center, New York, NY, USA.
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Giorgi A, Cer AT, Mohan S, Perreault MC. Excitatory and Inhibitory Descending Commissural Interneurons Differentially Integrate Supraspinal and Segmental Sensory Signals. J Neurosci 2023; 43:5014-5029. [PMID: 37286348 PMCID: PMC10324999 DOI: 10.1523/jneurosci.2015-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 05/26/2023] [Accepted: 06/02/2023] [Indexed: 06/09/2023] Open
Abstract
The limited information about how descending inputs from the brain and sensory inputs from the periphery use spinal cord interneurons (INs) is a major barrier to understanding how these inputs may contribute to motor functions under normal and pathologic conditions. Commissural interneurons (CINs) are a heterogeneous population of spinal INs that has been implicated in crossed motor responses and bilateral motor coordination (ability to use the right and left side of the body in a coordinated manner) and, therefore, are likely involved in many types of movement (e.g., dynamic posture stabilization, jumping, kicking, walking). In this study, we incorporate mouse genetics, anatomy, electrophysiology, and single-cell calcium imaging to investigate how a subset of CINs, those with descending axons called dCINs, are recruited by descending reticulospinal and segmental sensory signals independently and in combination. We focus on two groups of dCINs set apart by their principal neurotransmitter (glutamate and GABA) and identified as VGluT2+ dCINs and GAD2+ dCINs. We show that VGluT2+ and GAD2+ dCINs are both extensively recruited by reticulospinal and sensory input alone but that VGluT2+ and GAD2+ dCINs integrate these inputs differently. Critically, we find that when recruitment depends on the combined action of reticulospinal and sensory inputs (subthreshold inputs), VGluT2+ dCINs, but not GAD2+ dCINs, are recruited. This difference in the integrative capacity of VGluT2+ and GAD2+ dCINs represents a circuit mechanism that the reticulospinal and segmental sensory systems may avail themselves of to regulate motor behaviors both normally and after injury.SIGNIFICANCE STATEMENT The way supraspinal and peripheral sensory inputs use spinal cord interneurons is fundamental to defining how motor functions are supported both in health and disease. This study, which focuses on dCINs, a heterogeneous population of spinal interneurons critical for crossed motor responses and bilateral motor coordination, shows that both glutamatergic (excitatory) and GABAergic (inhibitory) dCINs can be recruited by supraspinal (reticulospinal) or peripheral sensory inputs. Additionally, the study demonstrates that in conditions where the recruitment of dCINs depends on the combined action of reticulospinal and sensory inputs, only excitatory dCINs are recruited. The study uncovers a circuit mechanism that the reticulospinal and segmental sensory systems may avail themselves of to regulate motor behaviors both normally and after injury.
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Affiliation(s)
- Andrea Giorgi
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Abishag Tluang Cer
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Shruthi Mohan
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
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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
The generation of an internal body model and its continuous update is essential in sensorimotor control. Although known to rely on proprioceptive sensory feedback, the underlying mechanism that transforms this sensory feedback into a dynamic body percept remains poorly understood. However, advances in the development of genetic tools for proprioceptive circuit elements, including the sensory receptors, are beginning to offer new and unprecedented leverage to dissect the central pathways responsible for proprioceptive encoding. Simultaneously, new data derived through emerging bionic neural machine-interface technologies reveal clues regarding the relative importance of kinesthetic sensory feedback and insights into the functional proprioceptive substrates that underlie natural motor behaviors.
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Affiliation(s)
- Paul D Marasco
- Laboratory for Bionic Integration, Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA;
- Charles Shor Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA
- Advanced Platform Technology Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Joriene C de Nooij
- Department of Neurology and the Columbia University Motor Neuron Center, Columbia University Medical Center, New York, NY, USA;
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11
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Arbat-Plana A, Bolívar S, Navarro X, Udina E, Alvarez FJ. Massive Loss of Proprioceptive Ia Synapses in Rat Spinal Motoneurons after Nerve Crush Injuries in the Postnatal Period. eNeuro 2023; 10:ENEURO.0436-22.2023. [PMID: 36759186 PMCID: PMC9948128 DOI: 10.1523/eneuro.0436-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/15/2022] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Peripheral nerve injuries (PNIs) induce the retraction from the ventral horn of the synaptic collaterals of Ia afferents injured in the nerve, effectively removing Ia synapses from α-motoneurons. The loss of Ia input impairs functional recovery and could explain, in part, better recovery after PNIs with better Ia synaptic preservation. Synaptic losses correlate with injury severity, speed, and efficiency of muscle reinnervation and requires ventral microglia activation. It is unknown whether this plasticity is age dependent. In neonates, axotomized motoneurons and sensory neurons undergo apoptosis, but after postnatal day 10 most survive. The goal of this study was to analyze vesicular glutamate transporter 1 (VGluT1)-labeled Ia synapses (which also include II afferents) after nerve crush in 10 day old rats, a PNI causing little Ia/II synapse loss in adult rats. We confirmed fast and efficient reinnervation of leg muscles; however, a massive number of VGluT1/Ia/II synapses were permanently lost. This synapse loss was similar to that after more severe nerve injuries involving full transection in adults. In adults, disappearance of ventrally directed Ia/II collaterals targeting α-motoneurons was associated with a prolonged microglia reaction and a CCR2 mechanism that included infiltration of CCR2 blood immune cells. By contrast, microgliosis after P10 injuries was fast, resolved in about a week, and there was no evidence of peripheral immune cell infiltration. We conclude that VGluT1/Ia/II synapse loss in young animals differs in mechanism, perhaps associated with higher microglia synaptic pruning activity at this age and results in larger losses after milder nerve injuries.
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Affiliation(s)
- Ariadna Arbat-Plana
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
- Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Sara Bolívar
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
- Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Xavier Navarro
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
| | - Esther Udina
- Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 08193 Bellaterra, Spain
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12
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Housley SN, Nardelli P, Rotterman TM, Reed J, Cope TC. Mechanosensory encoding dysfunction emerges from cancer-chemotherapy interaction. Front Mol Biosci 2022; 9:1017427. [PMID: 36504708 PMCID: PMC9729348 DOI: 10.3389/fmolb.2022.1017427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/20/2022] [Indexed: 11/25/2022] Open
Abstract
Persistent sensory, motor and cognitive disabilities comprise chemotherapy-induced neural disorders (CIND) that limit quality of life with little therapeutic relief for cancer survivors. Our recent preclinical study provides new insight into a condition impacting the severity of chronic CIND. We find that sensorimotor disability observed following cancer treatment exceeds that attributable to chemotherapy alone. A possible explanation for intensified disability emerged from evidence that codependent effects of cancer and chemotherapy amplify defective firing in primary sensory neurons supplying one type of low threshold mechanosensory receptor (LTMR). Here we test whether cancer's modification of chemotherapy-induced sensory defects generalizes across eight LTMR submodalities that collectively generate the signals of origin for proprioceptive and tactile perception and guidance of body movement. Preclinical study enabled controlled comparison of the independent contributions of chemotherapy and cancer to their clinically relevant combined effects. We compared data sampled from rats that were otherwise healthy or bearing colon cancer and treated, or not, with human-scaled, standard-of-care chemotherapy with oxaliplatin. Action potential firing patterns encoding naturalistic mechanical perturbations of skeletal muscle and skin were measured electrophysiologically in vivo from multiple types of LTMR neurons. All expressed aberrant encoding of dynamic and/or static features of mechanical stimuli in healthy rats treated with chemotherapy, and surprisingly also by some LTMRs in cancer-bearing rats that were not treated. By comparison, chemotherapy and cancer in combination worsened encoding aberrations, especially in slowly adapting LTMRs supplying both muscle and glabrous skin. Probabilistic modeling best predicted observed encoding defects when incorporating interaction effects of cancer and chemotherapy. We conclude that for multiple mechanosensory submodalities, the severity of encoding defects is modulated by a codependence of chemotherapy side effects and cancer's systemic processes. We propose that the severity of CIND might be reduced by therapeutically targeting the mechanisms, yet to be determined, by which cancer magnifies chemotherapy's neural side effects as an alternative to reducing chemotherapy and its life-saving benefits.
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Affiliation(s)
- Stephen N. Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States,Integrated Cancer Research Center, Georgia Institute of Technology, Atlanta, GA, United States,*Correspondence: Stephen N. Housley, ; Timothy C. Cope,
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Travis M. Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - J’Ana Reed
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Timothy C. Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States,Integrated Cancer Research Center, Georgia Institute of Technology, Atlanta, GA, United States,W. H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Georgia Institute of Technology, Atlanta, GA, United States,*Correspondence: Stephen N. Housley, ; Timothy C. Cope,
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13
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MS and GTO proprioceptor subtypes in the molecular genetic era: Opportunities for new advances and perspectives. Curr Opin Neurobiol 2022; 76:102597. [DOI: 10.1016/j.conb.2022.102597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 05/22/2022] [Accepted: 05/24/2022] [Indexed: 11/21/2022]
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14
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Hari K, Lucas-Osma AM, Metz K, Lin S, Pardell N, Roszko DA, Black S, Minarik A, Singla R, Stephens MJ, Pearce RA, Fouad K, Jones KE, Gorassini MA, Fenrich KK, Li Y, Bennett DJ. GABA facilitates spike propagation through branch points of sensory axons in the spinal cord. Nat Neurosci 2022; 25:1288-1299. [PMID: 36163283 PMCID: PMC10042549 DOI: 10.1038/s41593-022-01162-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/11/2022] [Indexed: 11/09/2022]
Abstract
Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.
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Affiliation(s)
- Krishnapriya Hari
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Krista Metz
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Shihao Lin
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Noah Pardell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - David A Roszko
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Anna Minarik
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Rahul Singla
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Marilee J Stephens
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kelvin E Jones
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Monica A Gorassini
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Cell Biology, Emory University, Atlanta, GA, USA
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada. .,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada.
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15
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Jankowska E. Basic principles of processing of afferent information by spinal interneurons. J Neurophysiol 2022; 128:689-695. [PMID: 36043802 DOI: 10.1152/jn.00344.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Integrative functions of spinal interneurons are well recognized but the relative role of different interneuronal populations in this process continues to be investigated. It therefore appeared useful to review the principles of integration of afferent information by the interneurons analyzed so far as these principles should apply also to those remaining to be analyzed. Considering the results of both functional and morphological studies of spinal interneurons and of the morphology and immunochemistry of afferent fibres that provide input to them, the following five basic principles of processing of afferent information by them will be outlined; (i) afferent information of any origin is forwarded to several neuronal populations, (ii) information from any sources of input is distributed unevenly, (iii) input from several sources is integrated by individual neurons as well as by their populations, (iv) specific combinations of input are integrated by different neuronal populations and (v) afferent input to spinal interneurons is only one of the features distinguishing their functional populations. As the spinal neuronal organization and properties of neurons and afferent fibres in the so far investigated species (cat, rodents, primates) have been found to resemble, future studies utilizing molecular techniques in the mouse should allow the new data to integrate with those of the preceding studies and the principles outlined above as well as any new ones should apply also in humans.
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Affiliation(s)
- Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Sweden
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16
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Qu N, Tian H, De Martino E, Zhang B. Neck Pain: Do We Know Enough About the Sensorimotor Control System? Front Comput Neurosci 2022; 16:946514. [PMID: 35910451 PMCID: PMC9337601 DOI: 10.3389/fncom.2022.946514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/24/2022] [Indexed: 11/13/2022] Open
Abstract
Neck pain is a worldwide health problem. Clarifying the etiology and providing effective interventions are challenging for the multifactorial nature of neck pain. As an essential component of cervical spine function, the sensorimotor control system has been extensively studied in both healthy and pathological conditions. Proprioceptive signals generated from cervical structures are crucial to normal cervical functions, and abnormal proprioception caused by neck pain leads to alterations in neural plasticity, cervical muscle recruitment and cervical kinematics. The long-term sensorimotor disturbance and maladaptive neural plasticity are supposed to contribute to the recurrence and chronicity of neck pain. Therefore, multiple clinical evaluations and treatments aiming at restoring the sensorimotor control system and neural plasticity have been proposed. This paper provides a short review on neck pain from perspectives of proprioception, sensorimotor control system, neural plasticity and potential interventions. Future research may need to clarify the molecular mechanism underlying proprioception and pain. The existing assessment methods of cervical proprioceptive impairment and corresponding treatments may need to be systematically reevaluated and standardized. Additionally, new precise motor parameters reflecting sensorimotor deficit and more effective interventions targeting the sensorimotor control system or neural plasticity are encouraged to be proposed.
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Affiliation(s)
- Ning Qu
- Department of Orthopedic Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - HaoChun Tian
- Department of Orthopedic Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Enrico De Martino
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
- Aerospace Medicine and Rehabilitation Laboratory, Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Bin Zhang
- Department of Orthopedic Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
- *Correspondence: Bin Zhang,
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17
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Thompson CK, Johnson MD, Negro F, Farina D, Heckman CJ. Motor Unit Discharge Patterns in Response to Focal Tendon Vibration of the Lower Limb in Cats and Humans. Front Integr Neurosci 2022; 16:836757. [PMID: 35558155 PMCID: PMC9087726 DOI: 10.3389/fnint.2022.836757] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
High-frequency vibration of the tendon provides potent activation of Ia afferents time-locked to the stimulation frequency and provides excitatory ionotropic activation of homonymous motor pools. In cats, the evoked motor unit discharge is constrained to discharge at integer multiples of the vibration frequency, resulting in a probability of discharge that is highly punctuated. Here we quantify the robustness of this punctuated response in the cat and evaluate whether it is present in the human. Soleus electromyography (EMG) was collected from eight cats using 64 channel electrodes during three modes of motoneuron activation. First, tendon vibration parameters were modified. Second, secondary reflex inputs are applied concurrently with tendon vibration. Third, the state of the spinal cord was altered through pharmacological or surgical manipulations. Analogous surface high-density EMG was collected from the lower leg of six humans during both vibration evoked and matched volitional contractions. Array EMG signals from both the cat and human were decomposed into corresponding motor unit action potential spike trains, and the punctuation in discharge was quantified. In the cat, regardless of vibration parameters, secondary synaptic drive, and state of spinal circuitry, focal tendon vibration evoked punctuated motor unit discharge. However, in the human lower limb, the vibration-evoked contractions do not produce punctuated motor unit discharge.
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Affiliation(s)
- Christopher K. Thompson
- Department of Health and Rehabilitation Sciences, Temple University, Philadelphia, PA, United States
| | - Michael D. Johnson
- Department of Physiology, Northwestern University, Chicago, IL, United States
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, Italy
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - C. J. Heckman
- Department of Physiology, Northwestern University, Chicago, IL, United States
- *Correspondence: C. J. Heckman,
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18
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Treatment with platelet-rich plasma attenuates proprioceptor abnormalities in a rat model of postpartum stress urinary incontinence. Int Urogynecol J 2022; 33:2159-2167. [PMID: 35195739 DOI: 10.1007/s00192-022-05112-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 01/27/2022] [Indexed: 12/23/2022]
Abstract
INTRODUCTION AND HYPOTHESIS Stress urinary incontinence (SUI) is the most prevalent form of urinary incontinence, and vaginal delivery is a major risk factor for developing SUI. We evaluated the hypothesis that applying the autologous platelet rich plasma (PRP) to the pelvic floor muscles via injection affects expression of proprioceptors and improves postpartum stress urinary incontinence (PSUI) in rats. METHODS Virgin female Sprague-Dawley rats were divided into control (n = 10) and experimental group(n = 20). Vaginal dilation was used to establish PSUI, and the rats in the experimental group were further divided into the PSUI group (n = 10) and PSUI+PRP group (n = 10). Pelvic floor muscles from rats in the PSUI+PRP group were positioned under ultrasound guidance for PRP injection. The morphology and number of pelvic floor muscle spindles were assessed using H&E staining, proprioceptors evaluated by gold chloride staining, and changes in the expression of neurotrophin-3 (NT-3) and skeletal myosin MY-32 determined by immunohistochemistry. RESULTS After 28 days,bladder leak point pressure (BLPP) and abdominal leaking-urine point pressure (ALPP) in rats with PSUI were significantly lower than in control animals (P<0.01). Both BLPP and ALPP increased significantly in the PSUI+PRP group (P<0.01). Compared with the control group, muscle spindle morphology and structure in the PSUI and PSUI+PRP groups had different pathological changes,with higher variations in the PSUI group. The positive signals for NT-3/MY-32 expression in control rats were higher than those from PSUI or PSUI+PRP groups, however, the expression for NT-3/MY-32 in PSUI+PRP animals was higher than that seen in the PSUI group (P < 0.01). CONCLUSIONS PSUI rats have an abnormal expression of pelvic proprioceptors, which affect proprioceptive function, and further the contractibility of pelvic floor muscles. A PRP injection may restore the sensory function of pelvic proprioceptors, thus improving urine leakage in PSUI rats.
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19
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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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20
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Housley SN, Nardelli P, Rotterman TM, Cope TC. Neural circuit mechanisms of sensorimotor disability in cancer treatment. Proc Natl Acad Sci U S A 2021; 118:e2100428118. [PMID: 34911753 PMCID: PMC8713769 DOI: 10.1073/pnas.2100428118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2021] [Indexed: 12/02/2022] Open
Abstract
Cancer survivors rank sensorimotor disability among the most distressing, long-term consequences of chemotherapy. Disorders in gait, balance, and skilled movements are commonly assigned to chemotoxic damage of peripheral sensory neurons without consideration of the deterministic role played by the neural circuits that translate sensory information into movement. This oversight precludes sufficient, mechanistic understanding and contributes to the absence of effective treatment for reversing chemotherapy-induced disability. We rectified this omission through the use of a combination of electrophysiology, behavior, and modeling to study the operation of a spinal sensorimotor circuit in vivo in a rat model of chronic, oxaliplatin (chemotherapy)-induced neuropathy (cOIN). Key sequential events were studied in the encoding of propriosensory information and its circuit translation into the synaptic potentials produced in motoneurons. In cOIN rats, multiple classes of propriosensory neurons expressed defective firing that reduced accurate sensory representation of muscle mechanical responses to stretch. Accuracy degraded further in the translation of propriosensory signals into synaptic potentials as a result of defective mechanisms residing inside the spinal cord. These sequential, peripheral, and central defects compounded to drive the sensorimotor circuit into a functional collapse that was consequential in predicting the significant errors in propriosensory-guided movement behaviors demonstrated here in our rat model and reported for people with cOIN. We conclude that sensorimotor disability induced by cancer treatment emerges from the joint expression of independent defects occurring in both peripheral and central elements of sensorimotor circuits.
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Affiliation(s)
- Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332;
- Integrated Cancer Research Center, Georgia Institute of Technology, Atlanta, GA 30309
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30309
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332
| | - Travis M Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332
| | - Timothy C Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332;
- Integrated Cancer Research Center, Georgia Institute of Technology, Atlanta, GA 30309
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30309
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA 30332
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21
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Banks RW, Ellaway PH, Prochazka A, Proske U. Secondary endings of muscle spindles: Structure, reflex action, role in motor control and proprioception. Exp Physiol 2021; 106:2339-2366. [PMID: 34676617 DOI: 10.1113/ep089826] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/11/2021] [Indexed: 01/04/2023]
Abstract
NEW FINDINGS What is the topic of this review? We describe the structure and function of secondary sensory endings of muscle spindles, their reflex action and role in motor control and proprioception. What advances does it highlight? In most mammalian skeletal muscles, secondary endings of spindles are more or much more numerous than primary endings but are much less well studied. By focusing on secondary endings in this review, we aim to redress the balance, draw attention to what is not known and stimulate future research. ABSTRACT Kinaesthesia and the control of bodily movement rely heavily on the sensory input from muscle spindles. Hundreds of these sensory structures are embedded in mammalian muscles. Each spindle has one or more sensory endings and its own complement of small muscle fibres that are activated by the CNS via fusimotor neurons, providing efferent control of sensory responses. Exactly how the CNS wields this influence remains the subject of much fascination and debate. There are two types of sensory endings, primary and secondary, with differing development, morphology, distribution and responsiveness. Spindle primary endings have received more attention than secondaries, although the latter usually outnumber them. This review focuses on the secondary endings. Their location within the spindle, their response properties, the projection of their afferents within the CNS and their reflex actions all suggest that secondaries have certain separate roles from the primaries in proprioception and motor control. Specifically, spindle secondaries seem more adapted than primaries to signalling slow and maintained changes in the relative position of bodily segments, thereby contributing to position sense, postural control and static limb positioning. By highlighting, in this way, the roles of secondary endings, a final aim of the review is to broaden understanding of muscle spindles more generally and of the important contributions they make to both sensory and motor mechanisms.
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Affiliation(s)
- Robert W Banks
- Department of Biosciences, Durham University, Durham, UK.,Biophysical Sciences Institute, Durham University, Durham, UK
| | - Peter H Ellaway
- Department of Brain Sciences, Imperial College London, London, UK
| | - Arthur Prochazka
- Division of Neuroscience, University of Alberta, Edmonton, Alberta, Canada
| | - Uwe Proske
- School of Biomedical Sciences, Monash University, Clayton, Victoria, Australia
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22
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Maas H, Noort W, Smilde HA, Vincent JA, Nardelli P, Cope TC. Detection of epimuscular myofascial forces by Golgi tendon organs. Exp Brain Res 2021; 240:147-158. [PMID: 34677632 PMCID: PMC8803698 DOI: 10.1007/s00221-021-06242-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 10/07/2021] [Indexed: 11/27/2022]
Abstract
Skeletal muscles embed multiple tendon organs, both at the proximal and distal ends of muscle fibers. One of the functions of such spatial distribution may be to provide locally unique force feedback, which may become more important when stresses are distributed non-uniformly within the muscle. Forces exerted by connections between adjacent muscles (i.e. epimuscular myofascial forces) may cause such local differences in force. The aim of this exploratory study was to investigate the effects of mechanical interactions between adjacent muscles on sensory encoding by tendon organs. Action potentials from single afferents were recorded intra-axonally in response to ramp-hold release (RHR) stretches of a passive agonistic muscle at different lengths or relative positions of its passive synergist. The tendons of gastrocnemius (GAS), plantaris (PL) and soleus (SO) muscles were cut from the skeleton for attachment to servomotors. Connective tissues among these muscles were kept intact. Lengthening GAS + PL decreased the force threshold of SO tendon organs (p = 0.035). The force threshold of lateral gastrocnemius (LG) tendon organs was not affected by SO length (p = 0.371). Also displacing LG + PL, kept at a constant muscle-tendon unit length, from a proximal to a more distal position resulted in a decrease in force threshold of LG tendon organs (p = 0.007). These results indicate that tendon organ firing is affected by changes in length and/or relative position of adjacent synergistic muscles. We conclude that tendon organs can provide the central nervous system with information about local stresses caused by epimuscular myofascial forces.
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Affiliation(s)
- Huub Maas
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
| | - Wendy Noort
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Hiltsje A Smilde
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
| | - Jacob A Vincent
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
| | - Paul Nardelli
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
- School of Biological Sciences and Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
- The Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Timothy C Cope
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, 45435, USA
- School of Biological Sciences and Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
- The Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
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23
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Kajtaz E, Montgomery LR, McMurtry S, Howland DR, Nichols TR. Non-uniform upregulation of the autogenic stretch reflex among hindlimb extensors following lateral spinal lesion in the cat. Exp Brain Res 2021; 239:2679-2691. [PMID: 34218298 PMCID: PMC9805805 DOI: 10.1007/s00221-020-06016-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 12/09/2020] [Indexed: 01/04/2023]
Abstract
Successful propagation throughout the step cycle is contingent on adequate regulation of whole-limb stiffness by proprioceptive feedback. Following spinal cord injury (SCI), there are changes in the strength and organization of proprioceptive feedback that can result in altered joint stiffness. In this study, we measured changes in autogenic feedback of five hindlimb extensor muscles following chronic low thoracic lateral hemisection (LSH) in decerebrate cats. We present three features of the autogenic stretch reflex obtained using a mechanographic method. Stiffness was a measure of the resistance to stretch during the length change. The dynamic index documented the extent of adaptation or increase of the force response during the hold phase, and the impulse measured the integral of the response from initiation of a stretch to the return to the initial length. The changes took the form of variable and transient increases in the stiffness of vastus (VASTI) group, soleus (SOL), and flexor hallucis longus (FHL), and either increased (VASTI) or decreased adaptation (GAS and PLANT). The stiffness of the gastrocnemius group (GAS) was also variable over time but remained elevated at the final time point. An unexpected finding was that these effects were observed bilaterally. Potential reasons for this finding and possible sources of increased excitability to this muscle group are discussed.
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Affiliation(s)
- E Kajtaz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30318, USA
| | - L R Montgomery
- Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery, The University of Louisville, Louisville, KY, USA
- Research Service, Robley Rex VA Medical Center, Louisville, KY, USA
| | - S McMurtry
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30318, USA
| | - D R Howland
- Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery, The University of Louisville, Louisville, KY, USA
- Research Service, Robley Rex VA Medical Center, Louisville, KY, USA
| | - T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30318, USA.
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24
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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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25
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Molecular correlates of muscle spindle and Golgi tendon organ afferents. Nat Commun 2021; 12:1451. [PMID: 33649316 PMCID: PMC7977083 DOI: 10.1038/s41467-021-21880-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 02/18/2021] [Indexed: 12/16/2022] Open
Abstract
Proprioceptive feedback mainly derives from groups Ia and II muscle spindle (MS) afferents and group Ib Golgi tendon organ (GTO) afferents, but the molecular correlates of these three afferent subtypes remain unknown. We performed single cell RNA sequencing of genetically identified adult proprioceptors and uncovered five molecularly distinct neuronal clusters. Validation of cluster-specific transcripts in dorsal root ganglia and skeletal muscle demonstrates that two of these clusters correspond to group Ia MS afferents and group Ib GTO afferent proprioceptors, respectively, and suggest that the remaining clusters could represent group II MS afferents. Lineage analysis between proprioceptor transcriptomes at different developmental stages provides evidence that proprioceptor subtype identities emerge late in development. Together, our data provide comprehensive molecular signatures for groups Ia and II MS afferents and group Ib GTO afferents, enabling genetic interrogation of the role of individual proprioceptor subtypes in regulating motor output. Coordinated movement critically depends on sensory feedback from muscle spindles (MSs) and Golgi tendon organs (GTOs) but the afferents supplying this proprioceptive feedback have remained genetically inseparable. Here the authors use single cell transcriptome analysis to reveal the molecular basis of MS (groups Ia and II) and GTO (group Ib) afferent identities in the mouse.
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26
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Zampieri N, de Nooij JC. Regulating muscle spindle and Golgi tendon organ proprioceptor phenotypes. CURRENT OPINION IN PHYSIOLOGY 2021; 19:204-210. [PMID: 33381667 PMCID: PMC7769215 DOI: 10.1016/j.cophys.2020.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Proprioception is an essential part of motor control. The main sensory subclasses that underlie this feedback control system - muscle spindle and Golgi tendon organ afferents - have been extensively characterized at a morphological and physiological level. More recent studies are beginning to reveal the molecular foundation for distinct proprioceptor subtypes, offering new insights into their developmental ontogeny and phenotypic diversity. This review intends to highlight some of these new findings.
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Affiliation(s)
- Niccolò Zampieri
- Max-Delbrück-Center for Molecular Medicine Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Joriene C. de Nooij
- Dept. of Neurology, Vagelos College of Physicians and Surgeons, Columbia University Medical Center, 630 West 168th Street, New York, NY 10032.,Columbia University Motor Neuron Center, Columbia University Medical Center, 630 West 168th Street, New York, NY 10032.,Corresponding author:
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27
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Holt E, Stanton-Turcotte D, Iulianella A. Development of the Vertebrate Trunk Sensory System: Origins, Specification, Axon Guidance, and Central Connectivity. Neuroscience 2021; 458:229-243. [PMID: 33460728 DOI: 10.1016/j.neuroscience.2020.12.037] [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] [Received: 08/24/2020] [Revised: 12/09/2020] [Accepted: 12/31/2020] [Indexed: 12/26/2022]
Abstract
Crucial to an animal's movement through their environment and to the maintenance of their homeostatic physiology is the integration of sensory information. This is achieved by axons communicating from organs, muscle spindles and skin that connect to the sensory ganglia composing the peripheral nervous system (PNS), enabling organisms to collect an ever-constant flow of sensations and relay it to the spinal cord. The sensory system carries a wide spectrum of sensory modalities - from sharp pain to cool refreshing touch - traveling from the periphery to the spinal cord via the dorsal root ganglia (DRG). This review covers the origins and development of the DRG and the cells that populate it, and focuses on how sensory connectivity to the spinal cord is achieved by the diverse developmental and molecular processes that control axon guidance in the trunk sensory system. We also describe convergences and differences in sensory neuron formation among different vertebrate species to gain insight into underlying developmental mechanisms.
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Affiliation(s)
- Emily Holt
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada
| | - Danielle Stanton-Turcotte
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada
| | - Angelo Iulianella
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, and Brain Repair Centre, Life Science Research Institute, 1348 Summer Street, Halifax, Nova Scotia B3H-4R2, Canada.
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28
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Borrell JA, Krizsan-Agbas D, Nudo RJ, Frost SB. Effects of a contusive spinal cord injury on cortically-evoked spinal spiking activity in rats. J Neural Eng 2020; 17:10.1088/1741-2552/abc1b5. [PMID: 33059344 PMCID: PMC8046849 DOI: 10.1088/1741-2552/abc1b5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/15/2020] [Indexed: 01/23/2023]
Abstract
Objective.The purpose of this study was to determine the effects of spinal cord injury (SCI) on spike activity evoked in the hindlimb spinal cord of the rat from cortical electrical stimulation.Approach.Adult, male, Sprague Dawley rats were randomly assigned to a Healthy or SCI group. SCI rats were given a 175 kDyn dorsal midline contusion injury at the level of the T8 vertebrae. At 4 weeks post-SCI, intracortical microstimulation (ICMS) was delivered at several sites in the hindlimb motor cortex of anesthetized rats, and evoked neural activity was recorded from corresponding sites throughout the dorsoventral depths of the spinal cord and EMG activity from hindlimb muscles.Main results.In healthy rats, post-ICMS spike histograms showed reliable, evoked spike activity during a short-latency epoch 10-12 ms after the initiation of the ICMS pulse train (short). Longer latency spikes occurred between ∼20 and 60 ms, generally following a Gaussian distribution, rising above baseline at timeLON, followed by a peak response (Lp), and then falling below baseline at timeLOFF. EMG responses occurred betweenLONandLp( 25-27 ms). In SCI rats, short-latency responses were still present, long-latency responses were disrupted or eliminated, and EMG responses were never evoked. The retention of the short-latency responses indicates that spared descending spinal fibers, most likely via the cortico-reticulospinal pathway, can still depolarize spinal cord neurons after a dorsal midline contusion injury.Significance.This study provides novel insights into the role of alternate pathways for voluntary control of hindlimb movements after SCI that disrupts the corticospinal tract in the rat.
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Affiliation(s)
- Jordan A. Borrell
- Bioengineering Program, University of Kansas, Lawrence, KS, USA
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
| | - Dora Krizsan-Agbas
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Randolph J. Nudo
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
- Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | - Shawn B. Frost
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
- Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS, USA
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29
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Housley SN, Nardelli P, Powers RK, Rich MM, Cope TC. Chronic defects in intraspinal mechanisms of spike encoding by spinal motoneurons following chemotherapy. Exp Neurol 2020; 331:113354. [PMID: 32511953 PMCID: PMC7937189 DOI: 10.1016/j.expneurol.2020.113354] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 05/04/2020] [Indexed: 11/22/2022]
Abstract
Chemotherapy-induced sensorimotor disabilities, including gait and balance disorders, as well as physical fatigue often persist for months and sometimes years into disease free survival from cancer. While associated with impaired sensory function, chronic sensorimotor disorders might also depend on chemotherapy-induced defects in other neuron types. In this report, we extend consideration to motoneurons, which, if chronically impaired, would necessarily degrade movement behavior. The present study was undertaken to determine whether motoneurons qualify as candidate contributors to chronic sensorimotor disability independently from sensory impairment. We tested this possibility in vivo from rats 5 weeks following human-scaled treatment with one of the platinum-based compounds, oxaliplatin, widely used in chemotherapy for a variety of cancers. Action potential firing of spinal motoneurons responding to different fixed levels of electrode-current injection was measured in order to assess the neurons' intrinsic capacity for stimulus encoding. The encoding of stimulus duration and intensity corroborated in untreated control rats was severely degraded in oxaliplatin treated rats, in which motoneurons invariably exhibited erratic firing that was unsustained, unpredictable from one stimulus trial to the next, and unresponsive to changes in current strength. Direct measurements of interspike oscillations in membrane voltage combined with computer modeling pointed to aberrations in subthreshold conductances as a plausible contributor to impaired firing behavior. These findings authenticate impaired spike encoding as a candidate contributor to, in the case of motoneurons, deficits in mobility and fatigue. Aberrant firing also becomes a deficit worthy of testing in other CNS neurons as a potential contributor to perceptual and cognitive disorders induced by chemotherapy in patients.
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Affiliation(s)
- Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA
| | - Randal K Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, USA
| | - Timothy C Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30318, USA; Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30318, USA.
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30
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Housley SN, Nardelli P, Carrasco DI, Rotterman TM, Pfahl E, Matyunina LV, McDonald JF, Cope TC. Cancer Exacerbates Chemotherapy-Induced Sensory Neuropathy. Cancer Res 2020; 80:2940-2955. [PMID: 32345673 PMCID: PMC7340531 DOI: 10.1158/0008-5472.can-19-2331] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 03/11/2020] [Accepted: 04/23/2020] [Indexed: 12/30/2022]
Abstract
For the constellation of neurologic disorders known as chemotherapy-induced peripheral neuropathy, mechanistic understanding and treatment remain deficient. Here, we present the first evidence that chronic sensory neuropathy depends on nonlinear interactions between cancer and chemotherapy. Global transcriptional profiling of dorsal root ganglia revealed differential expression, notably in regulators of neuronal excitability, metabolism, and inflammatory responses, all of which were unpredictable from effects observed with either chemotherapy or cancer alone. Systemic interactions between cancer and chemotherapy also determined the extent of deficits in sensory encoding and ion channel protein expression by single mechanosensory neurons, with the potassium ion channel Kv3.3 emerging as one potential contributor to sensory neuron dysfunction. Validated measures of sensorimotor behavior in awake, behaving animals revealed dysfunction after chronic chemotherapy treatment was exacerbated by cancer. Notably, errors in precise forelimb placement emerged as a novel behavioral deficit unpredicted by our previous study of chemotherapy alone. These original findings identify novel contributors to peripheral neuropathy and emphasize the fundamental dependence of neuropathy on the systemic interaction between chemotherapy and cancer. SIGNIFICANCE: These findings highlight the need to account for pathobiological interactions between cancer and chemotherapy as a major contributor to neuropathy and will have significant and immediate impact on future investigations in this field.
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Affiliation(s)
- Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Dario I Carrasco
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Travis M Rotterman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Emily Pfahl
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Lilya V Matyunina
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
- Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - John F McDonald
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
- Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
| | - Timothy C Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia.
- W.H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Georgia Institute of Technology, Atlanta, Georgia
- Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
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31
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Li Y, Hari K, Lucas-Osma AM, Fenrich KK, Bennett DJ, Hammar I, Jankowska E. Branching points of primary afferent fibers are vital for the modulation of fiber excitability by epidural DC polarization and by GABA in the rat spinal cord. J Neurophysiol 2020; 124:49-62. [PMID: 32459560 DOI: 10.1152/jn.00161.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The aim of the study was to examine whether the sustained increases in the excitability of afferent fibers traversing the dorsal columns evoked by their polarization depend on the branching points of these fibers. To this end, the effects of epidural polarization were compared in four spinal regions in deeply anesthetized rats; two with the densest collateralization of muscle afferent fibers (above motor nuclei and Clarke's column) and two where the collateralization is more sparse (rostral and caudal to motor nuclei, respectively. The degree of collateralization in different segments was reconstructed in retrogradely labeled afferent fibers in the rat. Nerve volleys evoked in peripheral nerves by electrical stimulation of the dorsal columns within these regions were used as a measure of the excitability of the stimulated fibers. Potent increases in the excitability were evoked by polarization above motor nuclei and Clarke's column, both during constant direct current (DC) polarization (1 µA for 1 min) and for at least 30 min following DC polarization. Smaller excitability increases occurred during the polarization within other regions and were thereafter either absent or rapidly declined after its termination. The postpolarization increases in excitability were counteracted by the GABAA receptor antagonist bicuculline and the α5GABAA extrasynaptic receptor antagonist L655708 and enhanced by the GABAA receptor agonist muscimol and by ionophoretically applied GABA. As extrasynaptic α5GABAA receptors have been found close to Na channels within branching points, these results are consistent with the involvement of branching points in the induction of the sustained postpolarization increases in fiber excitability.NEW & NOTEWORTHY Polarization of sensory fibers traversing dorsal columns of the spinal cord may considerably increase the excitability of these fibers. We show that this involves the effects of current at branching points of afferent fibers and depends on extrasynaptic effects of GABA. These results contribute to our understanding of the mechanism underlying plasticity of activation of nerve fibers and may be used to increase the effectiveness of epidural stimulation in humans and recovery of spinal functions.
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Affiliation(s)
- Yaqing Li
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Krishnapriya Hari
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Ingela Hammar
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
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32
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Alvarez FJ, Rotterman TM, Akhter ET, Lane AR, English AW, Cope TC. Synaptic Plasticity on Motoneurons After Axotomy: A Necessary Change in Paradigm. Front Mol Neurosci 2020; 13:68. [PMID: 32425754 PMCID: PMC7203341 DOI: 10.3389/fnmol.2020.00068] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/08/2020] [Indexed: 12/12/2022] Open
Abstract
Motoneurons axotomized by peripheral nerve injuries experience profound changes in their synaptic inputs that are associated with a neuroinflammatory response that includes local microglia and astrocytes. This reaction is conserved across different types of motoneurons, injuries, and species, but also displays many unique features in each particular case. These reactions have been amply studied, but there is still a lack of knowledge on their functional significance and mechanisms. In this review article, we compiled data from many different fields to generate a comprehensive conceptual framework to best interpret past data and spawn new hypotheses and research. We propose that synaptic plasticity around axotomized motoneurons should be divided into two distinct processes. First, a rapid cell-autonomous, microglia-independent shedding of synapses from motoneuron cell bodies and proximal dendrites that is reversible after muscle reinnervation. Second, a slower mechanism that is microglia-dependent and permanently alters spinal cord circuitry by fully eliminating from the ventral horn the axon collaterals of peripherally injured and regenerating sensory Ia afferent proprioceptors. This removes this input from cell bodies and throughout the dendritic tree of axotomized motoneurons as well as from many other spinal neurons, thus reconfiguring ventral horn motor circuitries to function after regeneration without direct sensory feedback from muscle. This process is modulated by injury severity, suggesting a correlation with poor regeneration specificity due to sensory and motor axons targeting errors in the periphery that likely render Ia afferent connectivity in the ventral horn nonadaptive. In contrast, reversible synaptic changes on the cell bodies occur only while motoneurons are regenerating. This cell-autonomous process displays unique features according to motoneuron type and modulation by local microglia and astrocytes and generally results in a transient reduction of fast synaptic activity that is probably replaced by embryonic-like slow GABA depolarizations, proposed to relate to regenerative mechanisms.
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Affiliation(s)
- Francisco J Alvarez
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Travis M Rotterman
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States.,Department of Biomedical Engineering, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Erica T Akhter
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Alicia R Lane
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Arthur W English
- Department of Cellular Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Timothy C Cope
- Department of Biomedical Engineering, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
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33
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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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34
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Horstman GM, Housley SN, Cope TC. Dysregulation of mechanosensory circuits coordinating the actions of antagonist motor pools following peripheral nerve injury and muscle reinnervation. Exp Neurol 2019; 318:124-134. [PMID: 31039333 PMCID: PMC6588415 DOI: 10.1016/j.expneurol.2019.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/23/2019] [Accepted: 04/26/2019] [Indexed: 12/29/2022]
Abstract
Movement disorders observed following peripheral nerve injury and muscle reinnervation suggest discoordination in the activation of antagonist muscles. Although underlying mechanisms remain undecided, dysfunction in spinal reflex circuits is a reasonable candidate. Based on the well known role of reflex inhibition between agonist and antagonist muscles in normal animals, we hypothesized its reduction following muscle reinnervation, similar to that associated with other disorders exhibiting antagonist discoordination, e.g. spinal cord injury and dystonia. Experiments performed on acutely-decerebrated rats examined interactions of mechanosensory reflexes between ipsilateral muscles acting as mechanical antagonists at the ankle joint: ankle extensor, gastrocnemii (G) muscles (agonists) and ankle flexor, tibialis anterior (TA) muscle (antagonist). The force of agonist stretch reflex contraction was measured for its suppression or facilitation by concurrent conditioning stretch of the antagonist muscle. Data were compared between two groups of adult rats, an antagonist reinnervation group with TA muscle reinnervated and a control group with TA normally innervated. Results revealed a three-fold increase in reflex suppression in the antagonist reinnervation group, contrary to our predicted decrease. Reflex facilitation also increased, not only in strength, seven-fold, but also in its frequency of stochastic occurrence across stimulus trials. These observations suggest dysregulation in specific spinal reflex circuits as novel candidate origins of modified antagonist muscle coordination following peripheral nerve injury and muscle reinnervation.
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Affiliation(s)
- Gabrielle M Horstman
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States of America
| | - Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
| | - Timothy C Cope
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States of America; School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States of America; W.H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Georgia Institute of Technology, Atlanta, GA 30332, United States of America.
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35
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Calcium Imaging of Parvalbumin Neurons in the Dorsal Root Ganglia. eNeuro 2019; 6:ENEURO.0349-18.2019. [PMID: 31311802 PMCID: PMC6709205 DOI: 10.1523/eneuro.0349-18.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 06/12/2019] [Accepted: 06/22/2019] [Indexed: 01/06/2023] Open
Abstract
We investigated the calcium dynamics of dorsal root ganglion (DRG) neurons using transgenic mice to target expression of the genetically encoded calcium indicator (GECI), GCaMP6s, to a subset of neurons containing parvalbumin (PV), a calcium-binding protein present in proprioceptors and low-threshold mechanoreceptors. This study provides the first analysis of GECI calcium transient parameters from large-diameter DRG neurons. Our approach generated calcium transients of consistent shape and time-course, with quantifiable characteristics. Four parameters of calcium transients were determined to vary independently from each other and thus are likely influenced by different calcium-regulating mechanisms: peak amplitude, rise time (RT), decay time, and recovery time. Pooled analysis of 188 neurons demonstrated unimodal distributions, providing evidence that PV+ DRG neurons regulate calcium similarly as a population despite their differences in size, electrical properties, and functional sensitivities. Calcium transients increased in size with elevated extracellular calcium, longer trains of action potentials, and higher stimulation frequencies. RT and decay time increased with the addition of the selective sarco/endoplasmic reticulum calcium ATPases (SERCA) blocker, thapsigargin (TG), while peak amplitude and recovery time remained the same. When elevating bath pH to 8.8 to block plasma-membrane calcium ATPases (PMCA), all measured parameters significantly increased. These results illustrate that GECI calcium transients provide sufficient resolution to detect changes in electrical activity and intracellular calcium concentration, as well as discern information about the activity of specific subclasses of calcium regulatory mechanisms.
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Modulation of soleus stretch reflexes during walking in people with chronic incomplete spinal cord injury. Exp Brain Res 2019; 237:2461-2479. [PMID: 31309252 PMCID: PMC6751142 DOI: 10.1007/s00221-019-05603-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/08/2019] [Indexed: 12/28/2022]
Abstract
In people with spasticity due to chronic incomplete spinal cord injury (SCI), it has been presumed that the abnormal stretch reflex activity impairs gait. However, locomotor stretch reflexes across all phases of walking have not been investigated in people with SCI. Thus, to understand modulation of stretch reflex excitability during spastic gait, we investigated soleus stretch reflexes across the entire gait cycle in nine neurologically normal participants and nine participants with spasticity due to chronic incomplete SCI (2.5–11 year post-injury). While the participant walked on the treadmill at his/her preferred speed, unexpected ankle dorsiflexion perturbations (6° at 250°/s) were imposed every 4–6 steps. The soleus H-reflex was also examined. In participants without SCI, spinal short-latency “M1”, spinal medium latency “M2”, and long-latency “M3” were clearly modulated throughout the step cycle; the responses were largest in the mid-stance and almost completely suppressed during the stance-swing transition and swing phases. In participants with SCI, M1 and M2 were abnormally large in the mid–late-swing phase, while M3 modulation was similar to that in participants without SCI. The H-reflex was also large in the mid–late-swing phase. Elicitation of H-reflex and stretch reflexes in the late swing often triggered clonus and affected the soleus activity in the following stance. In individuals without SCI, moderate positive correlation was found between H-reflex and stretch reflex sizes across the step cycle, whereas in participants with SCI, such correlation was weak to non-existing, suggesting that H-reflex investigation would not substitute for stretch reflex investigation in individuals after SCI.
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Lyle MA, Nichols TR. Evaluating intermuscular Golgi tendon organ feedback with twitch contractions. J Physiol 2019; 597:4627-4642. [PMID: 31228207 DOI: 10.1113/jp277363] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 06/11/2019] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS Golgi tendon organ feedback has been evaluated most frequently using electrical stimulation of peripheral nerves, which is not a physiological or selective stimulus for Golgi tendon organs. Golgi tendon organs are most responsive to active muscle contractions. This study provides evidence that muscle stimulation evoked twitches - a physiological stimulus for Golgi tendon organs - induces intermuscular effects most likely due to mechanical activation of Golgi tendon organ feedback and not direct activation of sensory axons. The results demonstrate that twitch contractions are a feasible non-invasive approach that can be used to advance understanding of the functional role of Golgi tendon organ feedback. ABSTRACT Force feedback from Golgi tendon organs (GTOs) has widespread intermuscular projections mediated by interneurons that share inputs from muscle spindles, among others. Because current methods to study GTO circuitry (nerve stimulation or muscle stretch) also activate muscle spindle afferents, the selective role of GTOs remains uncertain. Here, we tested the hypothesis that intramuscular stimulation evoked twitch contractions could be used to naturally bias activation of GTOs and thus evaluate their intermuscular effects in decerebrate cats. This was achieved by comparing the effects of twitch contractions and stretches as donor inputs onto the motor output of recipient muscles. Donor-recipient pairs evaluated included those already known in the cat to receive donor excitatory muscle spindle feedback only, inhibitory GTO feedback only, and both excitatory spindle and inhibitory GTO effects. Muscle stretch, but not twitch contractions, evoked excitation onto recipient muscles with muscle spindle afferent inputs only. Both donor muscle stretch and twitch contractions inhibited a recipient muscle with GTO projections only. In a recipient muscle that receives both muscle spindle and GTO projections, donor muscle stretch evoked both excitatory and inhibitory effects, whereas twitch contractions evoked inhibitory effects only. These data support the hypothesis that muscle stimulation evoked contractions can induce intermuscular effects most consistent with mechanical GTO receptor activation and not direct activation of sensory axons. We propose this approach can be used to evaluate GTO circuitry more selectively than muscle stretch or nerve stimulation and can be adapted to study GTO feedback non-invasively in freely moving cats and humans.
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Affiliation(s)
- Mark A Lyle
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, GA, 30332, USA
| | - T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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Manuel M, Chardon M, Tysseling V, Heckman CJ. Scaling of Motor Output, From Mouse to Humans. Physiology (Bethesda) 2019; 34:5-13. [PMID: 30540233 DOI: 10.1152/physiol.00021.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Appropriate scaling of motor output from mouse to humans is essential. The motoneurons that generate all motor output are, however, very different in rodents compared with humans, being smaller and much more excitable. In contrast, feline motoneurons are more similar to those in humans. These scaling differences need to be taken into account for the use of rodents for translational studies of motor output.
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Affiliation(s)
- Marin Manuel
- Centre de Neurophysique, Physiologie, et Pathologie, UMR 8119 CNRS/Université Paris Descartes , Paris , France
| | - Matthieu Chardon
- Physiology, Northwestern University Feinberg School of Medicine , Chicago, Illinois
| | - Vicki Tysseling
- Physical Therapy and Human Movement Sciences, Physiology, Northwestern University Feinberg School of Medicine , Chicago, Illinois
| | - C J Heckman
- Physiology, Physical Medicine and Rehabilitation, Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine , Chicago, Illinois
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Spinal Motor Circuit Synaptic Plasticity after Peripheral Nerve Injury Depends on Microglia Activation and a CCR2 Mechanism. J Neurosci 2019; 39:3412-3433. [PMID: 30833511 DOI: 10.1523/jneurosci.2945-17.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 02/03/2019] [Accepted: 02/27/2019] [Indexed: 12/24/2022] Open
Abstract
Peripheral nerve injury results in persistent motor deficits, even after the nerve regenerates and muscles are reinnervated. This lack of functional recovery is partly explained by brain and spinal cord circuit alterations triggered by the injury, but the mechanisms are generally unknown. One example of this plasticity is the die-back in the spinal cord ventral horn of the projections of proprioceptive axons mediating the stretch reflex (Ia afferents). Consequently, Ia information about muscle length and dynamics is lost from ventral spinal circuits, degrading motor performance after nerve regeneration. Simultaneously, there is activation of microglia around the central projections of peripherally injured Ia afferents, suggesting a possible causal relationship between neuroinflammation and Ia axon removal. Therefore, we used mice (both sexes) that allow visualization of microglia (CX3CR1-GFP) and infiltrating peripheral myeloid cells (CCR2-RFP) and related changes in these cells to Ia synaptic losses (identified by VGLUT1 content) on retrogradely labeled motoneurons. Microgliosis around axotomized motoneurons starts and peaks within 2 weeks after nerve transection. Thereafter, this region becomes infiltrated by CCR2 cells, and VGLUT1 synapses are lost in parallel. Immunohistochemistry, flow cytometry, and genetic lineage tracing showed that infiltrating CCR2 cells include T cells, dendritic cells, and monocytes, the latter differentiating into tissue macrophages. VGLUT1 synapses were rescued after attenuating the ventral microglial reaction by removal of colony stimulating factor 1 from motoneurons or in CCR2 global KOs. Thus, both activation of ventral microglia and a CCR2-dependent mechanism are necessary for removal of VGLUT1 synapses and alterations in Ia-circuit function following nerve injuries.SIGNIFICANCE STATEMENT Synaptic plasticity and reorganization of essential motor circuits after a peripheral nerve injury can result in permanent motor deficits due to the removal of sensory Ia afferent synapses from the spinal cord ventral horn. Our data link this major circuit change with the neuroinflammatory reaction that occurs inside the spinal cord following injury to peripheral nerves. We describe that both activation of microglia and recruitment into the spinal cord of blood-derived myeloid cells are necessary for motor circuit synaptic plasticity. This study sheds new light into mechanisms that trigger major network plasticity in CNS regions removed from injury sites and that might prevent full recovery of function, even after successful regeneration.
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Lucas-Osma AM, Li Y, Murray K, Lin S, Black S, Stephens MJ, Ahn AH, Heckman CJ, Fenrich KK, Fouad K, Bennett DJ. 5-HT 1D receptors inhibit the monosynaptic stretch reflex by modulating C-fiber activity. J Neurophysiol 2019; 121:1591-1608. [PMID: 30625007 DOI: 10.1152/jn.00805.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI, we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine, and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT1D receptors and not other 5-HT receptors. Selective 5-HT1D receptor antagonists blocked this agonist-induced inhibition, although antagonists alone had no action, indicating a lack of endogenous or constitutive receptor activity. In normal uninjured rats, the MSR was likewise inhibited by 5-HT, but at much higher doses, indicating a supersensitivity after SCI. This supersensitivity resulted from the loss of the serotonin transporter SERT with spinal transection, because normal and injured rats were equally sensitive to 5-HT after SERT was blocked or to agonists not transported by SERT (zolmitriptan). Immunolabeling revealed that the 5-HT1D receptor was confined to superficial lamina of the dorsal horn, colocalized with CGRP-positive C-fibers, and eliminated by dorsal rhizotomy. 5-HT1D receptor labeling was not found on large proprioceptive afferents or α-motoneurons of the MSR. Thus serotonergic inhibition of the MSR acts indirectly by modulating C-fiber activity, opening up new possibilities for modulating reflex function and clonus via pain-related pathways. NEW & NOTEWORTHY Brain stem-derived serotonin potently inhibits afferent transmission in the monosynaptic stretch reflex. We show that serotonin produces this inhibition exclusively via 5-HT1D receptors, and yet these receptors are paradoxically mostly confined to C-fibers. This suggests that serotonin acts by gating of C-fiber activity, which in turn modulates afferent transmission to motoneurons. We also show that the classic supersensitivity to 5-HT after spinal cord injury results from a loss of SERT, and not 5-HT1D receptor plasticity.
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Affiliation(s)
- Ana M Lucas-Osma
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Katie Murray
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Shihao Lin
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Marilee J Stephens
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Andrew H Ahn
- Teva Pharmaceuticals, Clinical Development, North Wales, Pennsylvania
| | - C J Heckman
- Department of Physiology, Northwestern University, Feinberg School of Medicine , Chicago, Illinois
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, Alberta , Canada
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Lucas-Osma AM, Li Y, Lin S, Black S, Singla R, Fouad K, Fenrich KK, Bennett DJ. Extrasynaptic α 5GABA A receptors on proprioceptive afferents produce a tonic depolarization that modulates sodium channel function in the rat spinal cord. J Neurophysiol 2018; 120:2953-2974. [PMID: 30256739 DOI: 10.1152/jn.00499.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of GABAA receptors on sensory axons produces a primary afferent depolarization (PAD) that modulates sensory transmission in the spinal cord. While axoaxonic synaptic contacts of GABAergic interneurons onto afferent terminals have been extensively studied, less is known about the function of extrasynaptic GABA receptors on afferents. Thus, we examined extrasynaptic α5GABAA receptors on low-threshold proprioceptive (group Ia) and cutaneous afferents. Afferents were impaled with intracellular electrodes and filled with neurobiotin in the sacrocaudal spinal cord of rats. Confocal microscopy was used to reconstruct the afferents and locate immunolabelled α5GABAA receptors. In all afferents α5GABAA receptors were found throughout the extensive central axon arbors. They were most densely located at branch points near sodium channel nodes, including in the dorsal horn. Unexpectedly, proprioceptive afferent terminals on motoneurons had a relative lack of α5GABAA receptors. When recording intracellularly from these afferents, blocking α5GABAA receptors (with L655708, gabazine, or bicuculline) hyperpolarized the afferents, as did blocking neuronal activity with tetrodotoxin, indicating a tonic GABA tone and tonic PAD. This tonic PAD was increased by repeatedly stimulating the dorsal root at low rates and remained elevated for many seconds after the stimulation. It is puzzling that tonic PAD arises from α5GABAA receptors located far from the afferent terminal where they can have relatively little effect on terminal presynaptic inhibition. However, consistent with the nodal location of α5GABAA receptors, we find tonic PAD helps produce sodium spikes that propagate antidromically out the dorsal roots, and we suggest that it may well be involved in assisting spike transmission in general. NEW & NOTEWORTHY GABAergic neurons are well known to form synaptic contacts on proprioceptive afferent terminals innervating motoneurons and to cause presynaptic inhibition. However, the particular GABA receptors involved are unknown. Here, we examined the distribution of extrasynaptic α5GABAA receptors on proprioceptive Ia afferents. Unexpectedly, these receptors were found preferentially near nodal sodium channels throughout the afferent and were largely absent from afferent terminals. These receptors produced a tonic afferent depolarization that modulated sodium spikes, consistent with their location.
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Affiliation(s)
- Ana M Lucas-Osma
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Shihao Lin
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Rahul Singla
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
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Kaczmarek D, Jankowska E. DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC. Neuroscience 2018; 374:236-249. [DOI: 10.1016/j.neuroscience.2018.01.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/16/2018] [Accepted: 01/17/2018] [Indexed: 12/20/2022]
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Nichols TR. Distributed force feedback in the spinal cord and the regulation of limb mechanics. J Neurophysiol 2018; 119:1186-1200. [PMID: 29212914 PMCID: PMC5899305 DOI: 10.1152/jn.00216.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 11/27/2017] [Accepted: 11/27/2017] [Indexed: 01/03/2023] Open
Abstract
This review is an update on the role of force feedback from Golgi tendon organs in the regulation of limb mechanics during voluntary movement. Current ideas about the role of force feedback are based on modular circuits linking idealized systems of agonists, synergists, and antagonistic muscles. In contrast, force feedback is widely distributed across the muscles of a limb and cannot be understood based on these circuit motifs. Similarly, muscle architecture cannot be understood in terms of idealized systems, since muscles cross multiple joints and axes of rotation and further influence remote joints through inertial coupling. It is hypothesized that distributed force feedback better represents the complex mechanical interactions of muscles, including the stresses in the musculoskeletal network born by muscle articulations, myofascial force transmission, and inertial coupling. Together with the strains of muscle fascicles measured by length feedback from muscle spindle receptors, this integrated proprioceptive feedback represents the mechanical state of the musculoskeletal system. Within the spinal cord, force feedback has excitatory and inhibitory components that coexist in various combinations based on motor task and integrated with length feedback at the premotoneuronal and motoneuronal levels. It is concluded that, in agreement with other investigators, autogenic, excitatory force feedback contributes to propulsion and weight support. It is further concluded that coexistent inhibitory force feedback, together with length feedback, functions to manage interjoint coordination and the mechanical properties of the limb in the face of destabilizing inertial forces and positive force feedback, as required by the accelerations and changing directions of both predator and prey.
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Affiliation(s)
- T Richard Nichols
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, Georgia
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Imai F, Yoshida Y. Molecular mechanisms underlying monosynaptic sensory-motor circuit development in the spinal cord. Dev Dyn 2018; 247:581-587. [PMID: 29226492 DOI: 10.1002/dvdy.24611] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 02/06/2023] Open
Abstract
Motor behaviors are precisely controlled by the integration of sensory and motor systems in the central nervous system (CNS). Proprioceptive sensory neurons, key components of the sensory system, are located in the dorsal root ganglia and project axons both centrally to the spinal cord and peripherally to muscles and tendons, communicating peripheral information about the body to the CNS. Changes in muscle length detected by muscle spindles, and tension variations in tendons conveyed by Golgi tendon organs, are communicated to the CNS through group Ia /II, and Ib proprioceptive sensory afferents, respectively. Group Ib proprioceptive sensory neurons connect with motor neurons indirectly through spinal interneurons, whereas group Ia/II axons form both direct (monosynaptic) and indirect connections with motor neurons. Although monosynaptic sensory-motor circuits between spindle proprioceptive sensory neurons and motor neurons have been extensively studied since 1950s, the molecular mechanisms underlying their formation and upkeep have only recently begun to be understood. We will discuss our current understanding of the molecular foundation of monosynaptic circuit development and maintenance involving proprioceptive sensory neurons and motor neurons in the mammalian spinal cord. Developmental Dynamics 247:581-587, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Fumiyasu Imai
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Yutaka Yoshida
- Divisions of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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