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Kilgore KL, Anderson KD, Peckham PH. Neuroprosthesis for individuals with spinal cord injury. Neurol Res 2023; 45:893-905. [PMID: 32727296 PMCID: PMC9415059 DOI: 10.1080/01616412.2020.1798106] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 07/14/2020] [Indexed: 01/31/2023]
Abstract
OBJECTIVE Individuals who sustain a traumatic spinal cord injury (SCI) often have a loss of multiple body systems. Significant functional improvement can be gained by individual SCI through the use of neuroprostheses based on electrical stimulation. The most common actions produced are grasp, overhead reach, trunk posture, standing, stepping, bladder/bowel/sexual function, and respiratory functions. METHODS We review the fundamental principles of electrical stimulation, which are established, allowing stimulation to be safely delivered through implanted devices for many decades. We review four common clinical applications for SCI, including grasp/reach, standing/stepping, bladder/bowel function, and respiratory functions. Systems used to implement these functions have many common features, but are also customized based on the functional goals of each approach. Further, neuroprosthetic systems are customized based on the needs of each user. RESULTS & CONCLUSION The results to date show that implanted neuroprostheses can have a significant impact on the health, function, and quality of life for individuals with SCI. A key focus for the future is to make implanted neuroprostheses broadly available to the SCI population.
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Affiliation(s)
- Kevin L. Kilgore
- – MetroHealth System, Cleveland, Ohio
- – Case Western Reserve University, Cleveland, Ohio
- – VA Northeast Ohio Healthcare System, Cleveland, Ohio
| | - Kimberly D. Anderson
- – MetroHealth System, Cleveland, Ohio
- – Case Western Reserve University, Cleveland, Ohio
| | - P. Hunter Peckham
- – MetroHealth System, Cleveland, Ohio
- – Case Western Reserve University, Cleveland, Ohio
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2
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MacDougall KB, Falconer TM, MacIntosh BR. Efficiency of cycling exercise: Quantification, mechanisms, and misunderstandings. Scand J Med Sci Sports 2022; 32:951-970. [PMID: 35253274 DOI: 10.1111/sms.14149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/19/2022] [Accepted: 02/09/2022] [Indexed: 12/24/2022]
Abstract
The energetics of cycling represents a well-studied area of exercise science, yet there are still many questions that remain. Efficiency, broadly defined as the ratio of energy output to energy input, is one key metric that, despite its importance from both a scientific as well as performance perspective, is commonly misunderstood. There are many factors that may affect cycling efficiency, both intrinsic (e.g., muscle fiber type composition) and extrinsic (e.g., cycling cadence, prior exercise, and training), creating a complex interplay of many components. Due to its relative simplicity, the measurement of oxygen uptake continues to be the most common means of measuring the energy cost of exercise (and thus efficiency); however, it is limited to only a small proportion of the range of outputs humans are capable of, further limiting our understanding of the energetics of high-intensity exercise and any mechanistic bases therein. This review presents evidence that delta efficiency does not represent muscular efficiency and challenges the notion that the slow component of oxygen uptake represents decreasing efficiency. It is noted that gross efficiency increases as intensity of exercise increases in spite of the fact that fast-twitch fibers are recruited to achieve this high power output. Understanding the energetics of high-intensity exercise will require critical evaluation of the available data.
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Affiliation(s)
- Keenan B MacDougall
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Tara M Falconer
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Brian R MacIntosh
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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3
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Thirumalai V, Jha U. Recruitment of Motoneurons. ADVANCES IN NEUROBIOLOGY 2022; 28:169-190. [PMID: 36066826 DOI: 10.1007/978-3-031-07167-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Beginning about half a century ago, the rules that determine how motor units are recruited during movement have been deduced. These classical experiments led to the formulation of the 'size principle'. It is now clear that motoneuronal size is not the only indicator of recruitment order. In fact, motoneuronal passive, active and synaptic conductances are carefully tuned to achieve sequential recruitment. More recent studies, over the last decade or so, show that the premotor circuitry is also functionally specialized and differentially recruited. Modular sub networks of interneurons and their post-synaptic motoneurons have been shown to drive movements with varying intensities. In addition, these modular networks are under the influence of neuromodulators, which are capable of acting upon multiple motor and premotor targets, thereby altering behavioral outcomes. We discuss the recruitment patterns of motoneurons in light of these new and exciting studies.
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Affiliation(s)
| | - Urvashi Jha
- National Centre for Biological Sciences, Bangalore, India
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4
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Bączyk M, Manuel M, Roselli F, Zytnicki D. Diversity of Mammalian Motoneurons and Motor Units. ADVANCES IN NEUROBIOLOGY 2022; 28:131-150. [PMID: 36066824 DOI: 10.1007/978-3-031-07167-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Although they share the common function of controlling muscle fiber contraction, spinal motoneurons display a remarkable diversity. Alpha-motoneurons are the "final common pathway", which relay all the information from spinal and supraspinal centers and allow the organism to interact with the outside world by controlling the contraction of muscle fibers in the muscles. On the other hand, gamma-motoneurons are specialized motoneurons that do not generate force and instead specifically innervate muscle fibers inside muscle spindles, which are proprioceptive organs embedded in the muscles. Beta-motoneurons are hybrid motoneurons that innervate both extrafusal and intrafusal muscle fibers. Even among alpha-motoneurons, there exists an exquisite diversity in terms of motoneuron electrical and molecular properties, physiological and structural properties of their neuromuscular junctions, and molecular and contractile properties of the innervated muscle fibers. This diversity, across species, across muscles, and across muscle fibers in a given muscle, underlie the vast repertoire of movements that one individual can perform.
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Affiliation(s)
- Marcin Bączyk
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Marin Manuel
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France.
| | - Francesco Roselli
- Department of Neurology, Ulm University, Ulm, Germany
- Institute of Anatomy and Cell Biology, Ulm University, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE)-Ulm, Ulm, Germany
- Neurozentrum Ulm, Ulm, Germany
| | - Daniel Zytnicki
- SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Université de Paris, Paris, France
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5
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Sharples SA, Miles GB. Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development. eLife 2021; 10:e71385. [PMID: 34783651 PMCID: PMC8641952 DOI: 10.7554/elife.71385] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 11/15/2021] [Indexed: 12/15/2022] Open
Abstract
The size principle underlies the orderly recruitment of motor units; however, motoneuron size is a poor predictor of recruitment amongst functionally defined motoneuron subtypes. Whilst intrinsic properties are key regulators of motoneuron recruitment, the underlying currents involved are not well defined. Whole-cell patch-clamp electrophysiology was deployed to study intrinsic properties, and the underlying currents, that contribute to the differential activation of delayed and immediate firing motoneuron subtypes. Motoneurons were studied during the first three postnatal weeks in mice to identify key properties that contribute to rheobase and may be important to establish orderly recruitment. We find that delayed and immediate firing motoneurons are functionally homogeneous during the first postnatal week and are activated based on size, irrespective of subtype. The rheobase of motoneuron subtypes becomes staggered during the second postnatal week, which coincides with the differential maturation of passive and active properties, particularly persistent inward currents. Rheobase of delayed firing motoneurons increases further in the third postnatal week due to the development of a prominent resting hyperpolarization-activated inward current. Our results suggest that motoneuron recruitment is multifactorial, with recruitment order established during postnatal development through the differential maturation of passive properties and sequential integration of persistent and hyperpolarization-activated inward currents.
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Affiliation(s)
- Simon A Sharples
- School of Psychology and Neuroscience, University of St AndrewsSt AndrewsUnited Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St AndrewsSt AndrewsUnited Kingdom
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6
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Kirk EA, Christie AD, Knight CA, Rice CL. Motor unit firing rates during constant isometric contraction: establishing and comparing an age-related pattern among muscles. J Appl Physiol (1985) 2021; 130:1903-1914. [PMID: 33914656 DOI: 10.1152/japplphysiol.01047.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motor unit (MU) firing rates (FRs) are lower in aged adults, compared with young, at relative voluntary contraction intensities. However, from a variety of independent studies of disparate muscles, the age-related degree of difference in FR among muscles is unclear. Using a standardized statistical approach with data derived from primary studies, we quantified differences in FRs across several muscles between younger and older adults. The data set included 12 different muscles in young (18-35 yr) and older adults (62-93 yr) from 18 published and one unpublished study. Experiments recorded single MU activity from intramuscular electromyography during constant isometric contraction at different (step-like) voluntary intensities. For each muscle, FR ranges and FR variance explained by voluntary contraction intensity were determined using bootstrapping. Dissimilarity of FR variance among muscles was calculated by Euclidean distances. There were threefold differences in the absolute frequency of FR ranges across muscles in the young (soleus 8-16 and superior trapezius 20-49 Hz), but in the old, FR ranges were more similar and lower for nine out of 12 muscles. In contrast, the explained FR variance from voluntary contraction intensity in the older group had 1.6-fold greater dissimilarity among muscles than the young (P < 0.001), with FR variance differences being muscle dependent. Therefore, differences between muscle FR ranges were not explained by how FRs scale to changes in voluntary contraction intensity within each muscle. Instead, FRs were muscle dependent but were more dissimilar among muscles in the older group in their responsiveness to voluntary contraction intensity.NEW & NOTEWORTHY The mean frequency of motor unit firing rates were compared systematically among several muscles and between young and older adults from new and published data sets. Firing rates among muscles were lower and more similar during voluntary isometric contraction in older than younger adults. Firing rate responses from voluntary contraction intensity were muscle dependent and more dissimilar among muscles in the older than young adults.
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Affiliation(s)
- Eric A Kirk
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Canada
| | - Anita D Christie
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Canada
| | - Christopher A Knight
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, Delaware
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada
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Do skeletal muscle motor units and microvascular units align to help match blood flow to metabolic demand? Eur J Appl Physiol 2021; 121:1241-1254. [PMID: 33538852 DOI: 10.1007/s00421-021-04598-4] [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: 09/23/2020] [Accepted: 01/10/2021] [Indexed: 10/22/2022]
Abstract
PURPOSE We explore the motor unit recruitment and control of perfusion of microvascular units in skeletal muscle to determine whether they coordinate to match blood flow to metabolic demand. METHODS The PubMed database was searched for historical, current and relevant literature. RESULTS A microvascular, or capillary unit consists of 2-20 individual capillaries. Individual capillaries within a capillary unit cannot increase perfusion independently of other capillaries within the unit. Capillary units perfuse a short segment of approx. 12 muscle fibres located beside each other. Motor units consist of muscle fibres that can be dispersed widely within the muscle volume. During a contraction, where not all motor units are recruited, muscle fibre contraction will result in increased perfusion of associated capillaries as well as all capillaries within that capillary unit. Perfusion of the entire capillary unit will result in an increased blood flow delivery to muscle fibres associated with active motor unit plus approximately 11 other inactive muscle fibres within the same region. This will result in an overperfusion of the muscle resulting in blood flow in excess of the muscle fibre needs. CONCLUSIONS Given the architecture of the capillary units and the dispersed nature of muscle fibres within a motor unit, during submaximal contractions, where not all motor units are recruited, there will be a greater perfusion to the muscle than that predicted by the number of active muscle fibres. Such overperfusion brings into question if blood flow and metabolic demand are as tightly matched as previously assumed.
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Azizi SA. Monoamines: Dopamine, Norepinephrine, and Serotonin, Beyond Modulation, "Switches" That Alter the State of Target Networks. Neuroscientist 2020; 28:121-143. [PMID: 33292070 DOI: 10.1177/1073858420974336] [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: 11/15/2022]
Abstract
How do monoamines influence the perceptual and behavioral aspects of brain function? A library of information regarding the genetic, molecular, cellular, and function of monoamines in the nervous system and other organs has accumulated. We briefly review monoamines' anatomy and physiology and discuss their effects on the target neurons and circuits. Monoaminergic cells in the brain stem receive inputs from sensory, limbic, and prefrontal areas and project extensively to the forebrain and hindbrain. We review selected studies on molecular, cellular, and electrophysiological effects of monoamines on the brain's target areas. The idea is that monoamines, by reversibly modulating the "primary" information processing circuits, regulate and switch the functions of brain networks and can reversibly alter the "brain states," such as consciousness, emotions, and movements. Monoamines, as the drivers of normal motor and sensory brain operations, including housekeeping, play essential roles in pathogenesis of neuropsychiatric diseases.
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Affiliation(s)
- Sayed Ausim Azizi
- Department of Neurology, Global Neuroscience Institute, Chester, PA, USA
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9
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Azevedo AW, Dickinson ES, Gurung P, Venkatasubramanian L, Mann RS, Tuthill JC. A size principle for recruitment of Drosophila leg motor neurons. eLife 2020; 9:e56754. [PMID: 32490810 PMCID: PMC7347388 DOI: 10.7554/elife.56754] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/01/2020] [Indexed: 11/28/2022] Open
Abstract
To move the body, the brain must precisely coordinate patterns of activity among diverse populations of motor neurons. Here, we use in vivo calcium imaging, electrophysiology, and behavior to understand how genetically-identified motor neurons control flexion of the fruit fly tibia. We find that leg motor neurons exhibit a coordinated gradient of anatomical, physiological, and functional properties. Large, fast motor neurons control high force, ballistic movements while small, slow motor neurons control low force, postural movements. Intermediate neurons fall between these two extremes. This hierarchical organization resembles the size principle, first proposed as a mechanism for establishing recruitment order among vertebrate motor neurons. Recordings in behaving flies confirmed that motor neurons are typically recruited in order from slow to fast. However, we also find that fast, intermediate, and slow motor neurons receive distinct proprioceptive feedback signals, suggesting that the size principle is not the only mechanism that dictates motor neuron recruitment. Overall, this work reveals the functional organization of the fly leg motor system and establishes Drosophila as a tractable system for investigating neural mechanisms of limb motor control.
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Affiliation(s)
- Anthony W Azevedo
- Department of Physiology and Biophysics, University of WashingtonSeattleUnited States
| | - Evyn S Dickinson
- Department of Physiology and Biophysics, University of WashingtonSeattleUnited States
| | - Pralaksha Gurung
- Department of Physiology and Biophysics, University of WashingtonSeattleUnited States
| | - Lalanti Venkatasubramanian
- Department of Biochemistry and Molecular Biophysics, Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia UniversityNew YorkUnited States
| | - Richard S Mann
- Department of Biochemistry and Molecular Biophysics, Department of Neuroscience, Zuckerman Mind Brain Behavior Institute, Columbia UniversityNew YorkUnited States
| | - John C Tuthill
- Department of Physiology and Biophysics, University of WashingtonSeattleUnited States
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10
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Tanabe Y, Torisu T, Tada H, Yamaguchi E, Murata H, De Laat A, Svensson P. Pain sensitivity after low-level clenching is influenced by preloading eccentric exercise. Odontology 2020; 109:29-40. [PMID: 32274673 DOI: 10.1007/s10266-020-00516-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 03/31/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE To examine the effect of preloading eccentric exercise on pain sensitivity in healthy volunteers. METHODS In 20 healthy volunteers, pain-related sensations (6 items: pain, unpleasantness, fatigue, stiffness, tension, and soreness during maximum biting), and pain intensities induced by repeated electrical stimuli on the masseter and the hand palm were evaluated using a visual analog scale (VAS) of 0-100 mm. Eccentric exercise (6 min-test) or gum chewing (6 min-control) was used as preloading exercise to evaluate the effect on pain sensitivities before and after low-level clenching (15 min) performed 2 days after the preloading exercise. RESULTS Eccentric exercise induced only low levels of pain-related sensations 2 days later. However, the time course of temporal summation induced by four repeated electrical stimuli on the masseter was influenced by the type of preloading exercise, i.e., temporal summation increased after the low-level clenching (P = 0.016) when preloading was done by the eccentric exercise, while no significant change was observed when preloading was done by the gum chewing. CONCLUSIONS Eccentric exercise may facilitate pain sensitivity induced by subsequent low-level clenching via the central nervous system. In addition, it was demonstrated that pain sensitivity after the low-level clenching could be influenced by the type of preloading exercise. These experimental results may suggest that eccentric exercise could act as one of the triggering factors in the mechanism by which tooth clenching leads to a chronic pain condition in susceptible individuals.
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Affiliation(s)
- Yuichi Tanabe
- Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8501, Japan
| | - Tetsurou Torisu
- Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8501, Japan.
| | - Hiroaki Tada
- Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8501, Japan
| | - Erika Yamaguchi
- Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8501, Japan
| | - Hiroshi Murata
- Department of Prosthetic Dentistry, Graduate School of Biomedical Sciences, Nagasaki University, Sakamoto 1-7-1, Nagasaki, 852-8501, Japan
| | - Antoon De Laat
- Department of Oral Health Sciences, KU Leuven, Leuven, Belgium.,Dentistry, University Hospitals Leuven, Kapucijnenvoer, 3000, Leuven, Belgium
| | - Peter Svensson
- Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.,Scandinavian Center for Orofacial Neurosciences (SCON), Vennelyst Boulevard 9, 8000, Aarhus C, Denmark.,Faculty of Odontology, Malmø University, Malmø, Sweden
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11
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E Kızıltan M, Gündüz A. Late component of trigemino-cervical reflex: changes according to age and gender. Neurol Sci 2020; 41:1759-1764. [PMID: 32006124 DOI: 10.1007/s10072-020-04242-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/06/2020] [Indexed: 10/25/2022]
Abstract
BACKGROUND Trigemino-cervical reflex (TCR) is a protective reflex which is elicited by the stimulation of any branch of the trigeminal nerve. After infraorbital stimulation, an early and late components have been described. The aim of this study was to find out whether there are age- or gender-related changes in the long-latency (RII) component of TCR. METHOD We included consecutive 53 healthy subjects (20 men, 37.7%) who had normal neurological examination. The mean age was 45.1 ± 14.3 years (age range 18-75 years). TCR was recorded simultaneously from bilateral sternocleidomastoid (SCM) and splenius capitis (SC) muscles with surface electrodes after stimulating right or left infraorbital branch of the trigeminal nerve, separately. We compared latency, amplitude, and duration according to gender and age. RESULTS The amplitudes of SC responses were significantly higher in women compared to men. The duration of SCM response was significantly longer in subjects above the age of 50 years compared to younger patients. The latency of the SC response was significantly delayed above the age of 40 years. CONCLUSION There are age- and gender-related changes in TCRs probably due to changes in the motoneurons of the SC and SCM muscles.
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Affiliation(s)
- Meral E Kızıltan
- Department of Neurology, Cerrahpaşa School of Medicine, IUC, Istanbul, Turkey
| | - Ayşegül Gündüz
- Department of Neurology, Cerrahpaşa School of Medicine, IUC, Istanbul, Turkey.
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12
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Qu W, Hou W, Zhao Y, Shu B, Chen L, Zheng X, Wang X, Wu X. Burst-modulated wide-pulse neuromuscular electrical stimulation enhances H-reflex recruitment in rats. Muscle Nerve 2020; 61:535-541. [PMID: 31950518 DOI: 10.1002/mus.26812] [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: 05/02/2019] [Revised: 01/04/2020] [Accepted: 01/11/2020] [Indexed: 11/10/2022]
Abstract
INTRODUCTION In this study we investigated whether burst-modulated wide-pulse neuromuscular electrical stimulation (NMES) can improve the H-reflex and activation efficiency of sensory fibers. METHODS NMES-induced electromyography (EMG) was recorded from hindpaw plantar muscles in 11 anesthetized rats. A burst-modulated wide pulse (mWP) with three carrier frequencies (2 kHz, 5 kHz, and 10 kHz) and a continuous wide-pulse (WP) were delivered to the tibial nerve of each rat. The evoked Hoffman (H)-reflexes were measured to evaluate nerve activation efficiency using the H-reflex recruitment curve (HRC). RESULTS Relative to WP simulation, mWP stimulation required less electrical charge to excite sensory fibers and improved the H-reflex recruitment. Greater electrical charge and smaller recruitment gains were obtained with increased carrier frequency of mWP. DISCUSSION mWP NMES can improve stimulation efficiency and improve recruitment of sensory fibers on tibial nerve stimulation, which may help to optimize NMES stimulus parameters.
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Affiliation(s)
- Wen Qu
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Wensheng Hou
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Yun Zhao
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Bin Shu
- Chongqing Medical Electronics Engineering Technology Research Center, Chongqing, China
| | - Lin Chen
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Xiaolin Zheng
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Xing Wang
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
| | - Xiaoying Wu
- Key Laboratory of Biorheological Science and Technology of Ministry of Education, Chongqing University, Chongqing, China
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13
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Shamim B, Devlin BL, Timmins RG, Tofari P, Lee Dow C, Coffey VG, Hawley JA, Camera DM. Adaptations to Concurrent Training in Combination with High Protein Availability: A Comparative Trial in Healthy, Recreationally Active Men. Sports Med 2019; 48:2869-2883. [PMID: 30341593 PMCID: PMC6244626 DOI: 10.1007/s40279-018-0999-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Background We implemented a high-protein diet (2 g·kg−1·d−1) throughout 12 weeks of concurrent exercise training to determine whether interferences to adaptation in muscle hypertrophy, strength and power could be attenuated compared to resistance training alone. Methods Thirty-two recreationally active males (age: 25 ± 5 years, body mass index: 24 ± 3 kg·m−2; mean ± SD) performed 12 weeks of either isolated resistance (RES; n = 10) or endurance (END; n = 10) training (three sessions·w−1), or concurrent resistance and endurance (CET; n = 12) training (six sessions·w−1). Maximal strength (1RM), body composition and power were assessed pre- and post-intervention. Results Leg press 1RM increased ~ 24 ± 13% and ~ 33 ± 16% in CET and RES from PRE-to-POST (P < 0.001), with no difference between groups. Total lean mass increased ~ 4% in both CET and RES from PRE-to-POST (P < 0.001). Ultrasound estimated vastus lateralis volume increased ~ 15% in CET and ~ 11% in RES from PRE-to-POST (P < 0.001), with no difference between groups. Wingate peak power relative to body mass displayed a trend (P = 0.053) to be greater in RES (12.5 ± 1.6 W·kg BM−1) than both CET (10.8 ± 1.7 W·kg BM−1) and END (10.9 ± 1.8 W·kg BM−1) at POST. Absolute VO2peak increased 6.9% in CET and 12% in END from PRE-to-POST (P < 0.05), with no difference between groups. Conclusion Despite high protein availability, select measures of anaerobic power-based adaptations, but not muscle strength or hypertrophy, appear susceptible to ‘interference effects’ with CET and should be closely monitored throughout training macro-cycles. Trials Registry: This trial was registered with the Australian-New Zealand Clinical Trials Registry (ACTRN12617001229369). Electronic supplementary material The online version of this article (10.1007/s40279-018-0999-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Baubak Shamim
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Brooke L Devlin
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Ryan G Timmins
- School of Exercise Science, Australian Catholic University, Melbourne, VIC, Australia
| | - Paul Tofari
- School of Exercise Science, Australian Catholic University, Melbourne, VIC, Australia
| | - Connor Lee Dow
- School of Exercise Science, Australian Catholic University, Melbourne, VIC, Australia
| | - Vernon G Coffey
- Bond Institute of Health and Sport and Faculty of Health Sciences and Medicine, Bond University, Robina, QLD, Australia
| | - John A Hawley
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Donny M Camera
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia.
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14
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Mouse incising central pattern generator: Characteristics and modulation by pain. Physiol Behav 2018; 196:8-24. [PMID: 30149084 DOI: 10.1016/j.physbeh.2018.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/23/2018] [Accepted: 08/23/2018] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Vertebrate incising and chewing are controlled by a set of neurons comprising the central pattern generator (CPG) for mastication. Mandibular positioning and force generation to perform these tasks is complex and requires coordination of multiple jaw opening and closing muscle compartments located in muscles on both sides of the jaw. The purpose of this study was to determine the characteristics of the CPG by recording mouse incising forces in the home cage environment to evaluate changes in force characteristics with incising frequency and force direction. A second purpose was to evaluate the effects of jaw closing muscle pain on CPG output parameters. METHODS Digitized incising forces were recorded for approximately 24 h using a 3-dimensional force transducer attached to solid food chow. Male and female CD-1 mice were evaluated during their last (fourth) baseline assessment and seven days after a second acidic saline injection into the left masseter muscle when maximum pain was experienced. Incising force resultants were calculated from the three axes data and force parameters were assessed including inter-peak intervals (IPI), peak amplitude, load time and unload time. Multiple regression analyses were conducted to identify incising episodes that had parameters of force that were significantly correlated (p < 0.001). These incising episodes were considered to represent the output of the CPG with a steady state of incoming sensory afferent inputs. Incising parameters were evaluated for each of the discrete incising frequencies (4.6, 5.3, 6.2, 7.6 Hz) and the predominant force directions: jaw closing (-Z), jaw retrusion (+X) and jaw protrusion (-X). RESULTS A significant correlation between incising frequency (IPI) and the load time was observed. A significant decrease in peak amplitude was observed with higher incising frequency while the load rate significantly increased. The force peak amplitude and load rates were found to be statistically different when the force direction was considered, with smaller peak amplitudes and smaller load rates found in the jaw closing direction. The effect of pain on incising was to reduce the peak amplitude and load rate of incising compared to the baseline condition at lower incising frequencies. CONCLUSIONS Like the central pattern generator for locomotion, the CPG for incising controls rhythmicity, peak amplitude and force load duration/rate. However, unlike the CPG for locomotion, the amplitude of incising force decreases as the frequency increases. During incising, load rate increases with faster rhythm and is consistent with the recruitment of larger motor units. Muscle pain reduced the excitatory drive of the CPG on motoneurons and provides further support of the Pain Adaptation Model.
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McPherson JG, McPherson LM, Thompson CK, Ellis MD, Heckman CJ, Dewald JPA. Altered Neuromodulatory Drive May Contribute to Exaggerated Tonic Vibration Reflexes in Chronic Hemiparetic Stroke. Front Hum Neurosci 2018; 12:131. [PMID: 29686611 PMCID: PMC5900019 DOI: 10.3389/fnhum.2018.00131] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 03/22/2018] [Indexed: 12/05/2022] Open
Abstract
Exaggerated stretch-sensitive reflexes are a common finding in elbow flexors of the contralesional arm in chronic hemiparetic stroke, particularly when muscles are not voluntarily activated prior to stretch. Previous investigations have suggested that this exaggeration could arise either from an abnormal tonic ionotropic drive to motoneuron pools innervating the paretic limbs, which could bring additional motor units near firing threshold, or from an increased influence of descending monoaminergic neuromodulatory pathways, which could depolarize motoneurons and amplify their responses to synaptic inputs. However, previous investigations have been unable to differentiate between these explanations, leaving the source(s) of this excitability increase unclear. Here, we used tonic vibration reflexes (TVRs) during voluntary muscle contractions of increasing magnitude to infer the sources of spinal motor excitability in individuals with chronic hemiparetic stroke. We show that when the paretic and non-paretic elbow flexors are preactivated to the same percentage of maximum prior to vibration, TVRs remain significantly elevated in the paretic arm. We also show that the rate of vibration-induced torque development increases as a function of increasing preactivation in the paretic limb, even though the amplitude of vibration-induced torque remains conspicuously unchanged as preactivation increases. It is highly unlikely that these findings could be explained by a source that is either purely ionotropic or purely neuromodulatory, because matching preactivation should control for the effects of a potential ionotropic drive (and lead to comparable tonic vibration reflex responses between limbs), while a purely monoaminergic mechanism would increase reflex magnitude as a function of preactivation. Thus, our results suggest that increased excitability of motor pools innervating the paretic limb post-stroke is likely to arise from both ionotropic and neuromodulatory mechanisms.
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Affiliation(s)
- Jacob G McPherson
- Department of Biomedical Engineering, Florida International University, Miami, FL, United States.,Department of Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Laura M McPherson
- Department of Biomedical Engineering, Florida International University, Miami, FL, United States.,Department of Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.,Department of Physical Therapy, Florida International University, Miami, FL, United States
| | - Christopher K Thompson
- Department of Physical Therapy, Temple University, Philadelphia, PA, United States.,Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Michael D Ellis
- Department of Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Charles J Heckman
- Department of Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.,Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
| | - Julius P A Dewald
- Department of Physical Therapy and Human Movement Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.,Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
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A distinct functional distribution of α and γ motoneurons in the rat trigeminal motor nucleus. Brain Struct Funct 2017; 222:3231-3239. [PMID: 28326439 DOI: 10.1007/s00429-017-1400-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/05/2017] [Indexed: 10/19/2022]
Abstract
Gamma-motoneurons (γMNs) play a crucial role in regulating isometric muscle contraction. The slow jaw-closing during mastication is one of the most functional isometric contractions, which is developed by the rank-order recruitment of alpha-motoneurons (αMNs) in a manner that reflects the size distribution of αMNs. In a mouse spinal motor nucleus, there are two populations of small and large MNs; the former was identified as a population of γMNs based on the positive expression of the transcription factor estrogen-related receptor 3 (Err3) and negative expression of the neuronal DNA-binding protein NeuN, and the latter as that of αMNs based on the opposite pattern of immunoreactivity. However, the differential identification of αMNs and γMNs in the trigeminal motor nucleus (TMN) remains an assumption based on the size of cell bodies that were retrogradely stained with HRP. We here examined the size distributions of αMNs and γMNs in the dorsolateral TMN (dl-TMN) by performing immunohistochemistry using anti-Err3 and anti-NeuN antibodies. The dl-TMN was identified by immunopositivity for vesicular glutamate transporter-1. Immunostaining for choline acetyltransferase and Err3/NeuN revealed that the dl-TMN is composed of 65% αMNs and 35% γMNs. The size distribution of αMNs was bimodal, while that of γMNs was almost the same as that of the population of small αMNs, suggesting the presence of αMNs as small as γMNs. Consistent with the size concept of motor units, the presence of smaller jaw-closing αMNs was coherent with the inclusion of jaw-closing muscle fibers with smaller diameters compared to limb muscle fibers.
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Gordon T, de Zepetnek JET. Motor unit and muscle fiber type grouping after peripheral nerve injury in the rat. Exp Neurol 2016; 285:24-40. [DOI: 10.1016/j.expneurol.2016.08.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/17/2016] [Accepted: 08/31/2016] [Indexed: 10/21/2022]
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The Possible Role of TASK Channels in Rank-Ordered Recruitment of Motoneurons in the Dorsolateral Part of the Trigeminal Motor Nucleus. eNeuro 2016; 3:eN-NWR-0138-16. [PMID: 27482536 PMCID: PMC4951569 DOI: 10.1523/eneuro.0138-16.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/21/2016] [Indexed: 01/11/2023] Open
Abstract
Because a rank-ordered recruitment of motor units occurs during isometric contraction of jaw-closing muscles, jaw-closing motoneurons (MNs) may be recruited in a manner dependent on their soma sizes or input resistances (IRs). In the dorsolateral part of the trigeminal motor nucleus (dl-TMN) in rats, MNs abundantly express TWIK (two-pore domain weak inwardly rectifying K channel)-related acid-sensitive-K(+) channel (TASK)-1 and TASK3 channels, which determine the IR and resting membrane potential. Here we examined how TASK channels are involved in IR-dependent activation/recruitment of MNs in the rat dl-TMN by using multiple methods. The real-time PCR study revealed that single large MNs (>35 μm) expressed TASK1 and TASK3 mRNAs more abundantly compared with single small MNs (15-20 μm). The immunohistochemistry revealed that TASK1 and TASK3 channels were complementarily distributed in somata and dendrites of MNs, respectively. The density of TASK1 channels seemed to increase with a decrease in soma diameter while there were inverse relationships between the soma size of MNs and IR, resting membrane potential, or spike threshold. Dual whole-cell recordings obtained from smaller and larger MNs revealed that the recruitment of MNs depends on their IRs in response to repetitive stimulation of the presumed Ia afferents. 8-Bromoguanosine-cGMP decreased IRs in small MNs, while it hardly changed those in large MNs, and subsequently decreased the difference in spike-onset latency between the smaller and larger MNs, causing a synchronous activation of MNs. These results suggest that TASK channels play critical roles in rank-ordered recruitment of MNs in the dl-TMN.
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Petrie M, Suneja M, Shields RK. Low-frequency stimulation regulates metabolic gene expression in paralyzed muscle. J Appl Physiol (1985) 2015; 118:723-31. [PMID: 25635001 DOI: 10.1152/japplphysiol.00628.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The altered metabolic state after a spinal cord injury compromises systemic glucose regulation. Skeletal muscle atrophies and transforms into fast, glycolytic, and insulin-resistant tissue. Osteoporosis is common after spinal cord injury and limits the ability to exercise paralyzed muscle. We used a novel approach to study the acute effect of two frequencies of stimulation (20 and 5 Hz) on muscle fatigue and gene regulation in people with chronic paralysis. Twelve subjects with chronic (>1 yr) and motor complete spinal cord injury (ASIA A) participated in the study. We assessed the twitch force before and after a single session of electrical stimulation (5 or 20 Hz). We controlled the total number of pulses delivered for each protocol (10,000 pulses). Three hours after the completion of the electrical stimulation (5 or 20 Hz), we sampled the vastus lateralis muscle and examined genes involved with metabolic transcription, glycolysis, oxidative phosphorylation, and mitochondria remodeling. We discovered that the 5-Hz stimulation session induced a similar amount of fatigue and a five- to sixfold increase (P < 0.05) in key metabolic transcription factors, including PGC-1α, NR4A3, and ABRA as the 20-Hz session. Neither session showed a robust regulation of genes for glycolysis, oxidative phosphorylation, or mitochondria remodeling. We conclude that a low-force and low-frequency stimulation session is effective at inducing fatigue and regulating key metabolic transcription factors in human paralyzed muscle. This strategy may be an acceptable intervention to improve systemic metabolism in people with chronic paralysis.
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Affiliation(s)
- Michael Petrie
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Manish Suneja
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa; and
| | - Richard K Shields
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa; Department of Veterans Affairs, Veterans Affairs Medical Center, Iowa City, Iowa
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Electrical stimulation site influences the spatial distribution of motor units recruited in tibialis anterior. Clin Neurophysiol 2013; 124:2257-63. [DOI: 10.1016/j.clinph.2013.04.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/16/2013] [Accepted: 04/22/2013] [Indexed: 11/18/2022]
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Binboğa E, Türker KS. Compound group I excitatory input is differentially distributed to human soleus motoneurons. Clin Neurophysiol 2012; 123:2192-9. [PMID: 22608971 DOI: 10.1016/j.clinph.2012.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/28/2012] [Accepted: 04/02/2012] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We studied whether the distribution of synaptic input from compound group I afferents onto the various-sized motoneurons in the human soleus muscle supports the size principle. METHODS The subject lay prone on a physiotherapy table and electrical stimuli were delivered to the tibial nerve. The recordings were taken with surface electromyography (SEMG) and single motor unit (SMU) potentials. The relative sizes of SMUs were estimated using four different methods. After identifying the relative size of each SMU of the pair, normalised size of the H-reflex was determined using the extra spike per trigger (ESPT) method. RESULTS In total 33 SMU pairs were studied to compare results obtained in each pair. It was found that, although the stimulus intensity was identical for each pair, the ESPT values were statistically larger in the bigger SMUs compared with the relatively smaller SMUs (p<0.05). CONCLUSIONS We conclude that, within the limits of this study, compound group I excitatory input to soleus motoneurons in human subjects does not support the size principle which governs the recruitment order of motoneurons in the reduced animal preparations. SIGNIFICANCE This study illustrates the importance of performing human experiments to confirm or reject principles obtained using reduced animal preparations.
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Affiliation(s)
- Erdal Binboğa
- Department of Biophysics, Ege University, Izmir, Turkey
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Carrascal L, Nieto-González JL, Torres B, Nunez-Abades P. Diminution of voltage threshold plays a key role in determining recruitment of oculomotor nucleus motoneurons during postnatal development. PLoS One 2011; 6:e28748. [PMID: 22174887 PMCID: PMC3235164 DOI: 10.1371/journal.pone.0028748] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 11/14/2011] [Indexed: 01/20/2023] Open
Abstract
The size principle dictates the orderly recruitment of motoneurons (Mns). This principle assumes that Mns of different sizes have a similar voltage threshold, cell size being the crucial property in determining neuronal recruitment. Thus, smaller neurons have higher membrane resistance and require a lower depolarizing current to reach spike threshold. However, the cell size contribution to recruitment in Mns during postnatal development remains unknown. To investigate this subject, rat oculomotor nucleus Mns were intracellularly labeled and their electrophysiological properties recorded in a brain slice preparation. Mns were divided into 2 age groups: neonatal (1-7 postnatal days, n = 14) and adult (20-30 postnatal days, n = 10). The increase in size of Mns led to a decrease in input resistance with a strong linear relationship in both age groups. A well-fitted inverse correlation was also found between input resistance and rheobase in both age groups. However, input resistance versus rheobase did not correlate when data from neonatal and adult Mns were combined in a single group. This lack of correlation is due to the fact that decrease in input resistance of developing Mns did not lead to an increase in rheobase. Indeed, a diminution in rheobase was found, and it was accompanied by an unexpected decrease in voltage threshold. Additionally, the decrease in rheobase co-varied with decrease in voltage threshold in developing Mns. These data support that the size principle governs the recruitment order in neonatal Mns and is maintained in adult Mns of the oculomotor nucleus; but during postnatal development the crucial property in determining recruitment order in these Mns was not the modifications of cell size-input resistance but of voltage threshold.
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Affiliation(s)
- Livia Carrascal
- Departamento de Fisiología, Universidad de Sevilla, Sevilla, Spain
| | | | - Blas Torres
- Departamento de Fisiología, Universidad de Sevilla, Sevilla, Spain
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Agostinucci J. The effects of circumferential pressure on the soleus muscle F-wave in healthy subjects. J Electromyogr Kinesiol 2011; 22:223-7. [PMID: 22000482 DOI: 10.1016/j.jelekin.2011.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 09/13/2011] [Accepted: 09/13/2011] [Indexed: 11/29/2022] Open
Abstract
Circumferential pressure (CP) was shown to decrease muscle activity in subjects without neuromuscular disorders and in individuals with spinal cord injury and cerebrovascular accidents. The mechanism for this decrease is unknown although it is hypothesized to be spinal in origin. The purpose of this study was to investigate the effect CP has on the soleus F-wave. Results will help determine the mechanism CP uses to effect motoneuron reflex excitability. Thirty-seven healthy volunteers participated. A 16cm air-splint was placed around the calf and during the pressure phase of the experiment it was inflated to 40-45mm Hg. F-waves were evoked by supra maximally stimulating (20%>Mmax) the tibial nerve with a 0.1ms pulse at 0.2Hz using a bipolar surface electrode on the skin of the popliteal fossa. Fifty F-waves were recorded before (baseline), during, and 3) after CP was applied. F-waves were then identified and mean latency, persistence, and mean F/Mmax amplitude ratios were measured and calculated. Friedman Repeated Measures on Ranks tests were conducted on each of the three parameters (p⩽0.05). No statistically significant difference was found for any of the F-wave parameters evaluated. These results were contrary to previous CP studies that observed a significant decrease in muscle activity. Possible reasons for this discrepancy are discussed.
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Affiliation(s)
- James Agostinucci
- Physical Therapy Department, University of Rhode Island, Kingston, RI, USA.
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MacIntosh BR, Esau SP, Holash RJ, Fletcher JR. Procedures for rat in situ skeletal muscle contractile properties. J Vis Exp 2011:e3167. [PMID: 22025076 PMCID: PMC3227207 DOI: 10.3791/3167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
There are many circumstances where it is desirable to obtain the contractile response of skeletal muscle under physiological circumstances: normal circulation, intact whole muscle, at body temperature. This includes the study of contractile responses like posttetanic potentiation, staircase and fatigue. Furthermore, the consequences of disease, disuse, injury, training and drug treatment can be of interest. This video demonstrates appropriate procedures to set up and use this valuable muscle preparation. To set up this preparation, the animal must be anesthetized, and the medial gastrocnemius muscle is surgically isolated, with the origin intact. Care must be taken to maintain the blood and nerve supplies. A long section of the sciatic nerve is cleared of connective tissue, and severed proximally. All branches of the distal stump that do not innervate the medial gastrocnemius muscle are severed. The distal nerve stump is inserted into a cuff lined with stainless steel stimulating wires. The calcaneus is severed, leaving a small piece of bone still attached to the Achilles tendon. Sonometric crystals and/or electrodes for electromyography can be inserted. Immobilization by metal probes in the femur and tibia prevents movement of the muscle origin. The Achilles tendon is attached to the force transducer and the loosened skin is pulled up at the sides to form a container that is filled with warmed paraffin oil. The oil distributes heat evenly and minimizes evaporative heat loss. A heat lamp is directed on the muscle, and the muscle and rat are allowed to warm up to 37°C. While it is warming, maximal voltage and optimal length can be determined. These are important initial conditions for any experiment on intact whole muscle. The experiment may include determination of standard contractile properties, like the force-frequency relationship, force-length relationship, and force-velocity relationship. With care in surgical isolation, immobilization of the origin of the muscle and alignment of the muscle-tendon unit with the force transducer, and proper data analysis, high quality measurements can be obtained with this muscle preparation.
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Kallenberg LAC, Hermens HJ. Motor unit properties of biceps brachii during dynamic contractions in chronic stroke patients. Muscle Nerve 2010; 43:112-9. [PMID: 20928907 DOI: 10.1002/mus.21803] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2010] [Indexed: 11/06/2022]
Abstract
The aim of this study was to investigate motor unit (MU) characteristics of the biceps brachii during sinusoidal contractions in chronic stroke patients using high-density surface electromyography. Ten sinusoidal elbow flexion and extension movements were performed both passively and actively by 18 stroke patients and 20 healthy subjects. Motor unit action potentials (MUAPs) were extracted, and their root-mean-square value (RMS(MUAP)) was calculated. RMS(MUAP) was significantly larger in stroke than in healthy subjects. In both groups RMS(MUAP) was smaller during the stretch phase of passive movement than during active movement. The larger MUAPs indicate enlarged MUs, possibly as a result of reinnervation. The lower RMS(MUAP) values during passive stretch than during active movement indicates that the stretch reflex mainly activates smaller MUs, while a larger part of the MU pool can be recruited voluntarily. RMS(MUAP) may have added value for monitoring changes in peripheral MU properties after stroke.
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Affiliation(s)
- Laura A C Kallenberg
- Roessingh Research and Development, PO Box 310, 7500 AH Enschede, The Netherlands.
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Lagerquist O, Collins DF. Influence of stimulus pulse width on M-waves, H-reflexes, and torque during tetanic low-intensity neuromuscular stimulation. Muscle Nerve 2010; 42:886-93. [PMID: 20886511 DOI: 10.1002/mus.21762] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2010] [Indexed: 11/09/2022]
Affiliation(s)
- Olle Lagerquist
- Human Neurophysiology Laboratory, Centre for Neuroscience, University of Alberta, Edmonton, Alberta T6G 2H9, Canada
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Assessment of Postural Muscle Strength in Sitting: Reliability of Measures Obtained with Hand-Held Dynamometry in Individuals with Spinal Cord Injury. J Neurol Phys Ther 2010; 34:24-31. [DOI: 10.1097/npt.0b013e3181cf5c49] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Evolutionary psychologists need to distinguish between the evolutionary process, ancestral selection pressures, and psychological mechanisms. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025577] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Selfishness reexamined: No man is an island. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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How useful is a concept such as muscle partitioning? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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The physiological basis and implications of differential motor activation. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Selfish genes and ingroup altruism. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A Comparative approach to muscle function. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x0002505x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
AbstractSocial dilemmas occur when the pursuit of self-interest by individuals in a group leads to less than optimal collective outcomes for everyone in the group. A critical assumption in the human sciences is that people's choices in such dilemmas are individualistic, selfish, and rational. Hence, cooperation in the support of group welfare will only occur if there are selfish incentives that convert the social dilemma into a nondilemma. In recent years, inclusive fitness theories have lent weight to such traditional views of rational selfishness on Darwinian grounds. To show that cooperation is based on selfish incentives, however, one must provide evidence that people do not cooperate without such incentives. In a series of experimental social dilemmas, subjects were instructed to make single, anonymous choices about whether or not to contribute money for a shared “bonus” that would be provided only if enough other people in the group also contributed their money. Noncontributors cited selfish reasons for their choices; contributors did not. If people are allowed to engage in discussion, they will contribute resources at high rates, frequently on irrational grounds, to promote group welfare. These findings are consistent with previous research on ingroup biasing effects that cannot be explained by “economic man” or “selfish gene” theories. An alternative explanation is that sociality was a primary factor shaping the evolution of Homo sapiens. The cognitive and affective mechanisms underlying such choices evolved under selection pressures on small groups for developing and maintaining group membership and for predicting and controlling the behavior of other group members. This sociality hypothesis organizes previously inexplicable and disparate phenomena in a Darwinian framework and makes novel predictions about human choice.
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Continuous and discrete models and measures of speech events. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Partitioning hypothesis in perspective. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A multiple source, or, is a striped apple more striped than a striped orange? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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The use of mathematical models in perceptual theory. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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