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Eisdorfer JT, Sobotka-Briner H, Schramfield S, Moukarzel G, Chen J, Campion TJ, Smit R, Rauscher BC, Lemay MA, Smith GM, Spence AJ. Chemogenetic modulation of sensory afferents induces locomotor changes and plasticity after spinal cord injury. Front Mol Neurosci 2022; 15:872634. [PMID: 36090254 PMCID: PMC9461563 DOI: 10.3389/fnmol.2022.872634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/26/2022] [Indexed: 12/12/2022] Open
Abstract
Neuromodulatory therapies for spinal cord injury (SCI) such as electrical epidural stimulation (EES) are increasingly effective at improving patient outcomes. These improvements are thought to be due, at least in part, to plasticity in neuronal circuits. Precisely which circuits are influenced and which afferent classes are most effective in stimulating change remain important open questions. Genetic tools, such as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs), support targeted and reversible neuromodulation as well as histological characterization of manipulated neurons. We therefore transduced and activated lumbar large diameter peripheral afferents with excitatory (hM3Dq) DREADDs, in a manner analogous to EES, in a rat hemisection model, to begin to trace plasticity and observe concomitant locomotor changes. Chronic DREADDs activation, coupled with thrice weekly treadmill training, was observed to increase afferent fluorescent labeling within motor pools and Clarke's column when compared to control animals. This plasticity may underlie kinematic differences that we observed across stages of recovery, including an increased and less variable hindquarters height in DREADDs animals, shorter step durations, a more flexed ankle joint early in recovery, a less variable ankle joint angle in swing phase, but a more variable hip joint angle. Withdrawal of DREADDs agonist, clozapine-N-oxide (CNO) left these kinematic differences largely unaffected; suggesting that DREADDs activation is not necessary for them later in recovery. However, we observed an intermittent “buckling” phenomenon in DREADDs animals without CNO activation, that did not occur with CNO re-administration. Future studies could use more refined genetic targeted of specific afferent classes, and utilize muscle recordings to find where afferent modulation is most influential in altering motor output.
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Affiliation(s)
- Jaclyn T. Eisdorfer
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, United States
| | - Hannah Sobotka-Briner
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Susan Schramfield
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - George Moukarzel
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Jie Chen
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Thomas J. Campion
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Rupert Smit
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Bradley C. Rauscher
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - Michel A. Lemay
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
| | - George M. Smith
- Department of Neuroscience, Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Andrew J. Spence
- Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, United States
- *Correspondence: Andrew J. Spence
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Fathi Y, Erfanian A. Decoding hindlimb kinematics from descending and ascending neural signals during cat locomotion. J Neural Eng 2021; 18. [PMID: 33395669 DOI: 10.1088/1741-2552/abd82a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 01/04/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The main objective of this research is to record both sensory and motor information from the ascending and descending tracts within the spinal cord for decoding the hindlimb kinematics during walking on the treadmill. APPROACH Two different experimental paradigms (i.e., active and passive) were used in the current study. During active experiments, five cats were trained to walk bipedally while their hands kept on the front frame of the treadmill for balance or to walk quadrupedally. During passive experiments, the limb was passively moved by the experimenter. Local field potential (LFP) activity was recorded using a microwire array implanted in the dorsal column (DC) and lateral column (LC) of the L3-L4 spinal segments. The amplitude and frequency components of the LFP formed the feature set and the elastic net regularization was used to decode the hindlimb joint angles. MAIN RESULTS The results show that there is no significant difference between the information content of the signals recorded from the DC and LC regions during walking on the treadmill, but the information content of the DC is significantly higher than that of the LC during passively applied movement of the hindlimb in the anesthetized cats. Moreover, the decoding performance obtained using the recorded signals from the DC is comparable with that from the LC during locomotion. But, the decoding performance obtained using the recording channels in the DC is significantly better than that obtained using the signals recorded from the LC. The long-term analysis shows that robust decoding performance can be achieved over 2-3 months without a significant decrease in performance. SIGNIFICANCE This work presents a promising approach to developing a natural and robust motor neuroprosthesis device using descending neural signals to execute the movement and ascending neural signals as the feedback information for control of the movement.
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Affiliation(s)
- Yaser Fathi
- Biomedical Engineering, Iran University of Science and Technology, Narmak, Resalat Square, Hengam Street, Iran University of Science and Technology, Tehran, Tehran, 16844, Iran (the Islamic Republic of)
| | - Abbas Erfanian
- Biomedical Engineering, Iran University of Science & Technology, Hengam Street, Narmak, Tehran 16844, Iran, Tehran, 16844, IRAN, ISLAMIC REPUBLIC OF
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Harrison SJ. Human Odometry with a Two-Legged Hopping Gait: A Test of the Gait Symmetry Theory. ECOLOGICAL PSYCHOLOGY 2020. [DOI: 10.1080/10407413.2019.1708200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Steven J. Harrison
- Doctoral Physical Therapy Program, Department of Kinesiology, University of Connecticut
- Center for the Ecological Study of Perception and Action, Department of Psychological Sciences, University of Connecticut
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Neuromechanical control of leg length and orientation in children and adults during single-leg hopping. Exp Brain Res 2019; 237:1745-1757. [DOI: 10.1007/s00221-019-05548-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/24/2019] [Indexed: 10/26/2022]
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Amemiya K, Morita T, Saito DN, Ban M, Shimada K, Okamoto Y, Kosaka H, Okazawa H, Asada M, Naito E. Local-to-distant development of the cerebrocerebellar sensorimotor network in the typically developing human brain: a functional and diffusion MRI study. Brain Struct Funct 2019; 224:1359-1375. [PMID: 30729998 PMCID: PMC6499876 DOI: 10.1007/s00429-018-01821-5] [Citation(s) in RCA: 10] [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: 10/04/2018] [Accepted: 12/16/2018] [Indexed: 01/19/2023]
Abstract
Sensorimotor function is a fundamental brain function in humans, and the cerebrocerebellar circuit is essential to this function. In this study, we demonstrate how the cerebrocerebellar circuit develops both functionally and anatomically from childhood to adulthood in the typically developing human brain. We measured brain activity using functional magnetic resonance imaging while a total of 57 right-handed, blindfolded, healthy children (aged 8-11 years), adolescents (aged 12-15 years), and young adults (aged 18-23 years) (n = 19 per group) performed alternating extension-flexion movements of their right wrists in precise synchronization with 1-Hz audio tones. We also collected their diffusion MR images to examine the extent of fiber maturity in cerebrocerebellar afferent and efferent tracts by evaluating the anisotropy-sensitive index of hindrance modulated orientational anisotropy (HMOA). During the motor task, although the ipsilateral cerebellum and the contralateral primary sensorimotor cortices were consistently activated across all age groups, the functional connectivity between these two distant regions was stronger in adults than in children and adolescents, whereas connectivity within the local cerebellum was stronger in children and adolescents than in adults. The HMOA values in cerebrocerebellar afferent and efferent tracts were higher in adults than in children (some were also higher than in adolescents). The results indicate that adult-like cerebrocerebellar functional coupling is not completely achieved during childhood and adolescence, even for fundamental sensorimotor brain function, probably due to anatomical immaturity of cerebrocerebellar tracts. This study clearly demonstrated the principle of "local-to-distant" development of functional brain networks in the human cerebrocerebellar sensorimotor network.
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Affiliation(s)
- Kaoru Amemiya
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), 1-4 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Tomoyo Morita
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), 1-4 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Daisuke N Saito
- Research Center for Child Mental Development, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Research Center for Child Mental Development, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa, 920-8640, Japan
| | - Midori Ban
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Koji Shimada
- Research Center for Child Mental Development, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
| | - Yuko Okamoto
- Research Center for Child Mental Development, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- ATR Promotions, 2-2 Hikaridai, Seika, Soraku-gun, Kyoto, 619-0288, Japan
| | - Hirotaka Kosaka
- Research Center for Child Mental Development, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
| | - Hidehiko Okazawa
- Research Center for Child Mental Development, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
- Biomedical Imaging Research Center, University of Fukui, 23-3 Matsuoka-shimoaizuki, Eiheiji, Yoshida, Fukui, 910-1193, Japan
| | - Minoru Asada
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), 1-4 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Eiichi Naito
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), 1-4 Yamadaoka, Suita, Osaka, 565-0871, Japan.
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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Fathi Y, Erfanian A. A probabilistic recurrent neural network for decoding hind limb kinematics from multi-segment recordings of the dorsal horn neurons. J Neural Eng 2019; 16:036023. [PMID: 30849772 DOI: 10.1088/1741-2552/ab0e51] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Providing accurate and robust estimates of limb kinematics from recorded neural activities is prominent in closed-loop control of functional electrical stimulation (FES). A major issue in providing accurate decoding the limb kinematics is the decoding model. The primary goal of this study is to develop a decoding approach to model the dynamic interactions of neural systems for accurate decoding. Another critical issue is to find reliable recording sites. Up to now, neural recordings from spinal neural activities were investigated. In this paper, the neural recordings from different vertebrae in decoding limb kinematics are investigated. APPROACH In the current study, a new generative probabilistic model with explicit considering the joint density is developed. Then, an adaptive discriminative learning algorithm is proposed for learning the model. It will be shown that the proposed generative process can be implemented by a recurrent neural network (RNN) with specific structure. We record the neural activities from dorsal horn neurons by using three electrodes placed in the L4, L5, and L6 vertebrae in anesthetized cats. MAIN RESULTS Information theoretic analysis on single-joint movement and multi-segment recordings implies the rostrocaudal distribution of kinematic information. It is demonstrated that during hip movement, best decoding performance is achieved by L4 recordings. For knee and ankle movements, best decodings are achieved by L5, and L6 recordings respectively. It is also shown that the decoding accuracy using multi-segment recordings outperforms decoding accuracy obtained by single-segment recording in multi-joint movement. The results also confirm the superiority of the proposed probabilistic recurrent neural network (PRNN) over the conventional recurrent neural network and Kalman filter ([Formula: see text]). SIGNIFICANCE Multi-segment recordings from dorsal horn neurons as well as the proposed probabilistic recurrent network model provide a promising approach for robust and accurate decoding limb kinematics.
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Affiliation(s)
- Yaser Fathi
- Department of Biomedical Engineering, Iran Neural Technology Research Centre, Iran University of Science and Technology (IUST), Tehran, Iran
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Chang YH, Housley SN, Hart KS, Nardelli P, Nichols RT, Maas H, Cope TC. Progressive adaptation of whole-limb kinematics after peripheral nerve injury. Biol Open 2018; 7:7/8/bio028852. [PMID: 30082274 PMCID: PMC6124561 DOI: 10.1242/bio.028852] [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] [Indexed: 12/27/2022] Open
Abstract
The ability to recover purposeful movement soon after debilitating neuromuscular injury is essential to animal survival. Various neural and mechanical mechanisms exist to preserve whole-limb kinematics despite exhibiting long-term deficits of individual joints following peripheral nerve injury. However, it is unclear whether functionally relevant whole-limb movement is acutely conserved following injury. Therefore, the objective of this longitudinal study of the injury response from four individual cats was to test the hypothesis that whole-limb length is conserved following localized nerve injury of ankle extensors in cats with intact nervous systems. The primary finding of our study was that whole-limb kinematics during walking was not immediately preserved following peripheral nerve injuries that paralyzed subsets of ankle extensor muscles. Instead, whole-limb kinematics recovered gradually over multiple weeks, despite having the mechanical capacity of injury-spared muscles across all joints to achieve immediate functional recovery. The time taken to achieve complete recovery of whole-limb kinematics is consistent with an underlying process that relies on neuromuscular adaptation. Importantly, the gradual recovery of ankle joint kinematics remained incomplete, discontinuing once whole-limb kinematics had fully recovered. These findings support the hypothesis that a whole-limb representation of healthy limb function guides a locomotor compensation strategy after neuromuscular injury that arrests progressive changes in the joint kinematics once whole-limb kinematics is regained.
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Affiliation(s)
- Young-Hui Chang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Stephen N Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Kerry S Hart
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio 45435, USA
| | - Paul Nardelli
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio 45435, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Richard T Nichols
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Huub Maas
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, 1081 HV Amsterdam, Netherlands
| | - Timothy C Cope
- Department of Neuroscience, Cell Biology and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio 45435, USA .,School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.,The Coulter Department of Biomedical Engineering Georgia Tech College of Engineering and Emory School of Medicine Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Yeganegi H, Fathi Y, Erfanian A. Decoding hind limb kinematics from neuronal activity of the dorsal horn neurons using multiple level learning algorithm. Sci Rep 2018; 8:577. [PMID: 29330489 PMCID: PMC5766487 DOI: 10.1038/s41598-017-18971-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/19/2017] [Indexed: 01/05/2023] Open
Abstract
Decoding continuous hind limb joint angles from sensory recordings of neural system provides a feedback for closed-loop control of hind limb movement using functional electrical stimulation. So far, many attempts have been done to extract sensory information from dorsal root ganglia and sensory nerves. In this work, we examine decoding joint angles trajectories from the single-electrode extracellular recording of dorsal horn gray matter of the spinal cord during passive limb movement in anesthetized cats. In this study, a processing framework based on ensemble learning approach is propose to combine firing rate (FR) and interspike interval (ISI) information of the neuronal activity. For this purpose, a stacked generalization approach based on recurrent neural network is proposed to enhance decoding accuracy of the movement kinematics. The results show that the high precision neural decoding of limb movement can be achieved even with a single electrode implanted in the spinal cord gray matter.
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Affiliation(s)
- Hamed Yeganegi
- Department of Biomedical Engineering, School of electrical engineering, Iran Neural Technology Research Center, Iran University of Science and Technology (IUST), Tehran, Iran
| | - Yaser Fathi
- Department of Biomedical Engineering, School of electrical engineering, Iran Neural Technology Research Center, Iran University of Science and Technology (IUST), Tehran, Iran
| | - Abbas Erfanian
- Department of Biomedical Engineering, School of electrical engineering, Iran Neural Technology Research Center, Iran University of Science and Technology (IUST), Tehran, Iran.
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Valle MS, Bosco G, Poppele RE. Cerebellar compartments for the processing of kinematic and kinetic information related to hindlimb stepping. Exp Brain Res 2017; 235:3437-3448. [PMID: 28835990 DOI: 10.1007/s00221-017-5067-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/14/2017] [Indexed: 12/19/2022]
Abstract
We previously showed that proprioceptive sensory input from the hindlimbs to the anterior cerebellar cortex of the cat may not be simply organized with respect to a body map, but it may also be distributed to multiple discrete functional areas extending beyond classical body map boundaries. With passive hindlimb stepping movements, cerebellar activity was shown to relate to whole limb kinematics as does the activity of dorsal spinocerebellar tract (DSCT) neurons. For DSCT activity, whole limb kinematics provides a solid functional framework within which information about limb forces, such as those generated during active stepping, may also be embedded. In this study, we investigated this idea for the spinocerebellar cortex activity by examining the activity of cerebellar cortical neurons during both passive bipedal hindlimb stepping and active stepping on a treadmill. Our results showed a functional compartmentalization of cerebellar responses to hindlimb stepping movements depending on the two types of stepping and strong relationships between neural activities and limb axis kinematics during both. In fact, responses to passive and active stepping were generally different, but in both cases their waveforms were related strongly to the limb axis kinematics. That is, the different stepping conditions modified the kinematics representation without producing different components in the response waveforms. In sum, cerebellar activity was consistent with a global kinematics framework serving as a basis upon which detailed information about limb mechanics and/or about individual limb segments might be imposed.
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Affiliation(s)
- M S Valle
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Catania, Italy
| | - G Bosco
- Department of Neuroscience and CBMS, University of Rome "Tor Vergata", Rome, Italy.,IRCSS Santa Lucia Foundation, Rome, Italy
| | - R E Poppele
- Department of Neuroscience, University of Minnesota, 321 Church St SE, Minneapolis, MN, 55455, USA.
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Abstract
Proper execution of voluntary movement requires a sensorimotor transformation based on the initial limb state. For example, successfully reaching to a stable target requires the recruitment of different muscle groups depending on limb position at movement initiation. To test whether this transformation could occur at the spinal level, we stimulated the cervical spinal cord of anesthetized monkeys while systematically changing initial posture and examined the modulation of the twitch response induced in the upper limb muscles. In three monkeys, a multichannel microelectrode array was implanted into the C6 segment of the spinal cord and electromyographic electrodes were implanted in 12 limb muscles (five hand, four elbow, and three shoulder muscles). The magnitude and onset latency of the evoked response in each electrode-muscle pair were examined by systematically changing the hand position through nine positions in a horizontal plane with the monkey prone. Among 330 electrode-muscle pairs examined, 61% of pairs exhibited significant modulation of either magnitude or latency of twitch responses across different hand/arm configurations (posture dependency). We found that posture dependency occurred preferentially in the distal rather than proximal muscles and was not affected by the location of the electrode within the stimulated spinal segment. Importantly, this posture dependency was not affected by spinalization at the C2 level. These results suggest that excitability in the cervical spinal cord is affected by initial arm posture through spinal reflex pathways. This posture dependency of spinal motor output could affect voluntary arm movement by adjusting descending motor commands relative to the initial arm posture.
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Stecina K, Fedirchuk B, Hultborn H. Information to cerebellum on spinal motor networks mediated by the dorsal spinocerebellar tract. J Physiol 2013; 591:5433-43. [PMID: 23613538 DOI: 10.1113/jphysiol.2012.249110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The main objective of this review is to re-examine the type of information transmitted by the dorsal and ventral spinocerebellar tracts (DSCT and VSCT respectively) during rhythmic motor actions such as locomotion. Based on experiments in the 1960s and 1970s, the DSCT was viewed as a relay of peripheral sensory input to the cerebellum in general, and during rhythmic movements such as locomotion and scratch. In contrast, the VSCT was seen as conveying a copy of the output of spinal neuronal circuitry, including those circuits generating rhythmic motor activity (the spinal central pattern generator, CPG). Emerging anatomical and electrophysiological information on the putative subpopulations of DSCT and VSCT neurons suggest differentiated functions for some of the subpopulations. Multiple lines of evidence support the notion that sensory input is not the only source driving DSCT neurons and, overall, there is a greater similarity between DSCT and VSCT activity than previously acknowledged. Indeed the majority of DSCT cells can be driven by spinal CPGs for locomotion and scratch without phasic sensory input. It thus seems natural to propose the possibility that CPG input to some of these neurons may contribute to distinguishing sensory inputs that are a consequence of the active locomotion from those resulting from perturbations in the external world.
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Affiliation(s)
- Katinka Stecina
- K. Stecina: University of Copenhagen, Department of Neuroscience and Pharmacology, The Panum Institute, 33.3, Blegdamsvej 3, Copenhagen 2200, Denmark.
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Spanne A, Jörntell H. Processing of multi-dimensional sensorimotor information in the spinal and cerebellar neuronal circuitry: a new hypothesis. PLoS Comput Biol 2013; 9:e1002979. [PMID: 23516353 PMCID: PMC3597523 DOI: 10.1371/journal.pcbi.1002979] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 01/23/2013] [Indexed: 02/08/2023] Open
Abstract
Why are sensory signals and motor command signals combined in the neurons of origin of the spinocerebellar pathways and why are the granule cells that receive this input thresholded with respect to their spike output? In this paper, we synthesize a number of findings into a new hypothesis for how the spinocerebellar systems and the cerebellar cortex can interact to support coordination of our multi-segmented limbs and bodies. A central idea is that recombination of the signals available to the spinocerebellar neurons can be used to approximate a wide array of functions including the spatial and temporal dependencies between limb segments, i.e. information that is necessary in order to achieve coordination. We find that random recombination of sensory and motor signals is not a good strategy since, surprisingly, the number of granule cells severely limits the number of recombinations that can be represented within the cerebellum. Instead, we propose that the spinal circuitry provides useful recombinations, which can be described as linear projections through aspects of the multi-dimensional sensorimotor input space. Granule cells, potentially with the aid of differentiated thresholding from Golgi cells, enhance the utility of these projections by allowing the Purkinje cell to establish piecewise-linear approximations of non-linear functions. Our hypothesis provides a novel view on the function of the spinal circuitry and cerebellar granule layer, illustrating how the coordinating functions of the cerebellum can be crucially supported by the recombinations performed by the neurons of the spinocerebellar systems.
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Affiliation(s)
- Anton Spanne
- Neural basis for Sensorimotor Control, BMC F10, Lund University, SE-22184 Lund, Sweden
| | - Henrik Jörntell
- Neural basis for Sensorimotor Control, BMC F10, Lund University, SE-22184 Lund, Sweden
- * E-mail:
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Gizzi L, Nielsen JF, Felici F, Moreno JC, Pons JL, Farina D. Motor modules in robot-aided walking. J Neuroeng Rehabil 2012; 9:76. [PMID: 23043818 PMCID: PMC3533908 DOI: 10.1186/1743-0003-9-76] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 10/01/2012] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND It is hypothesized that locomotion is achieved by means of rhythm generating networks (central pattern generators) and muscle activation generating networks. This modular organization can be partly identified from the analysis of the muscular activity by means of factorization algorithms. The activity of rhythm generating networks is described by activation signals whilst the muscle intervention generating network is represented by motor modules (muscle synergies). In this study, we extend the analysis of modular organization of walking to the case of robot-aided locomotion, at varying speed and body weight support level. METHODS Non Negative Matrix Factorization was applied on surface electromyographic signals of 8 lower limb muscles of healthy subjects walking in gait robotic trainer at different walking velocities (1 to 3 km/h) and levels of body weight support (0 to 30%). RESULTS The muscular activity of volunteers could be described by low dimensionality (4 modules), as for overground walking. Moreover, the activation signals during robot-aided walking were bursts of activation timed at specific phases of the gait cycle, underlying an impulsive controller, as also observed in overground walking. This modular organization was consistent across the investigated speeds, body weight support level, and subjects. CONCLUSIONS These results indicate that walking in a Lokomat robotic trainer is achieved by similar motor modules and activation signals as overground walking and thus supports the use of robotic training for re-establishing natural walking patterns.
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Affiliation(s)
- Leonardo Gizzi
- Pain Clinic, Center for Anesthesiology, Emergency and Intensive Care Medicine, University Hospital Göttingen, Göttingen, Germany
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Kim SH, Banala SK, Brackbill EA, Agrawal SK, Krishnamoorthy V, Scholz JP. Robot-assisted modifications of gait in healthy individuals. Exp Brain Res 2010; 202:809-24. [PMID: 20186402 DOI: 10.1007/s00221-010-2187-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2008] [Accepted: 02/04/2010] [Indexed: 01/14/2023]
Abstract
This study investigated whether short-term modifications of gait could be induced in healthy adults and whether a combination of kinetic (a compliant force resisting deviation of the foot from the prescribed footpath) and visual guidance was superior to either kinetic guidance or visual guidance alone in producing this modification. Thirty-nine healthy adults, 20-33 years old, were randomly assigned to the three groups receiving six 10-min blocks of treadmill training requiring them to modify their footpath to match a scaled-down path. Changes of the footpath, specific joint events and joint moments were analyzed. Persons receiving combined kinetic and visual guidance showed larger modifications of their gait patterns that were maintained longer, persisting up to 2 h after intervening over-ground activities, than did persons receiving training with primarily kinetic guidance or with visual guidance alone. The results emphasize the short-term plasticity of locomotor circuits and provide a possible basis for persons learning to achieve more functional gait patterns following a stroke or other neurological disorders.
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Affiliation(s)
- Seok Hun Kim
- School of Physical Therapy and Rehabilitation Sciences, University of South Florida, Tampa, FL 33612, USA.
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16
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Chang YH, Auyang AG, Scholz JP, Nichols TR. Whole limb kinematics are preferentially conserved over individual joint kinematics after peripheral nerve injury. ACTA ACUST UNITED AC 2010; 212:3511-21. [PMID: 19837893 DOI: 10.1242/jeb.033886] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Biomechanics and neurophysiology studies suggest whole limb function to be an important locomotor control parameter. Inverted pendulum and mass-spring models greatly reduce the complexity of the legs and predict the dynamics of locomotion, but do not address how numerous limb elements are coordinated to achieve such simple behavior. As a first step, we hypothesized whole limb kinematics were of primary importance and would be preferentially conserved over individual joint kinematics after neuromuscular injury. We used a well-established peripheral nerve injury model of cat ankle extensor muscles to generate two experimental injury groups with a predictable time course of temporary paralysis followed by complete muscle self-reinnervation. Mean trajectories of individual joint kinematics were altered as a result of deficits after injury. By contrast, mean trajectories of limb orientation and limb length remained largely invariant across all animals, even with paralyzed ankle extensor muscles, suggesting changes in mean joint angles were coordinated as part of a long-term compensation strategy to minimize change in whole limb kinematics. Furthermore, at each measurement stage (pre-injury, paralytic and self-reinnervated) step-by-step variance of individual joint kinematics was always significantly greater than that of limb orientation. Our results suggest joint angle combinations are coordinated and selected to stabilize whole limb kinematics against short-term natural step-by-step deviations as well as long-term, pathological deviations created by injury. This may represent a fundamental compensation principle allowing animals to adapt to changing conditions with minimal effect on overall locomotor function.
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Affiliation(s)
- Young-Hui Chang
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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17
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Neuromechanical stabilization of leg length and orientation through interjoint compensation during human hopping. Exp Brain Res 2008; 192:253-64. [PMID: 18839158 DOI: 10.1007/s00221-008-1582-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Accepted: 09/17/2008] [Indexed: 10/21/2022]
Abstract
Evidence for the simplification of motor control of the limbs through a reduction in the number of degrees of freedom exists in areas of research such as neuroscience, robotics, and biomechanics. Human hopping in place can be modeled well with spring-mass dynamics and provides a tractable model by which to study how the locomotor system compensates through inter-joint coordination to achieve stability of performance variables, leg length and orientation. This study provides the first evidence for how the redundancy of human leg joints may be simply coordinated to stabilize spring-mass dynamics throughout the hopping cycle using an uncontrolled manifold (UCM) analysis. We use a UCM analysis to quantify the structure of joint variance that stabilizes the hypothesized performance variables, leg length and leg orientation. For one-legged human hopping in place, we hypothesized that leg length and orientation would each be stabilized throughout the entire hopping cycle. We also hypothesized that hopping at non-preferred frequencies would be more difficult for subjects and stabilization of leg length and orientation would increase. Kinematic data from eleven subjects hopping at three frequencies (2.2, 2.8, and 3.2 Hz) were collected and analyzed within the framework of the UCM. Maximum leg length stabilization was observed at mid-stance when leg length was most susceptible to small changes in joint angles. Overall stabilization of leg length increased as subjects hopped at higher frequencies, reflecting the increased demands on the control system. The stabilization of leg orientation during aerial phase acted to position the foot at initial contact to determine velocity and trajectory of the center of mass during the stance phase. Because hopping in place does not require a change in forward velocity, the control strategy for leg orientation remained the same across frequencies. We conclude that stabilization of leg length and orientation may signify a reduction in degrees of freedom in the control system.
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Changes in synaptic effectiveness of myelinated joint afferents during capsaicin-induced inflammation of the footpad in the anesthetized cat. Exp Brain Res 2008; 187:71-84. [PMID: 18251018 DOI: 10.1007/s00221-008-1281-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 01/10/2008] [Indexed: 12/20/2022]
Abstract
The present series of experiments was designed to examine, in the anesthetized cat, the extent to which the synaptic efficacy of knee joint afferents is modified during the state of central sensitization produced by the injection of capsaicin into the hindlimb plantar cushion. We found that the intradermic injection of capsaicin increased the N2 and N3 components of the focal potentials produced by stimulation of intermediate and high threshold myelinated fibers in the posterior articular nerve (PAN), respectively. This facilitation lasted several hours, had about the same time course as the paw inflammation and was more evident for the N2 and N3 potentials recorded within the intermediate zone in the L6 than in the L7 spinal segments. The capsaicin-induced facilitation of the N2 focal potentials, which are assumed to be generated by activation of fibers signaling joint position, suggests that nociception may affect the processing of proprioceptive and somato-sensory information and, probably also, movement. In addition, the increased effectiveness of these afferents could activate, besides neurons in the intermediate region, neurons located in the more superficial layers of the dorsal horn. As a consequence, normal joint movements could produce pain representing a secondary hyperalgesia. The capsaicin-induced increased efficacy of the PAN afferents producing the N3 focal potentials, together with the reduced post-activation depression that follows high frequency autogenetic stimulation of these afferents, could further contribute to the pain sensation from non-inflamed joints during skin inflammation in humans. The persistence, after capsaicin, of the inhibitory effects produced by stimulation of cutaneous nerves innervating non-inflamed skin regions may account for the reported reduction of the articular pain sensations produced by trans-cutaneous stimulation.
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Pollok B, Butz M, Gross J, Südmeyer M, Timmermann L, Schnitzler A. Coupling between cerebellar hemispheres: behavioural, anatomic, and functional data. THE CEREBELLUM 2006; 5:212-9. [PMID: 16997753 DOI: 10.1080/14734220600621294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Although the cerebellum has been related to emotional, cognitive, and sensory processes, its outstanding significance for motor behaviour has attracted a vast variety of studies. Specifically, the role of cerebellar activity for appropriate movement timing has been investigated intensively. Behavioural studies, particularly of patients following cerebellar lesions, gave rise to the hypothesis that each hand is controlled by separate timing mechanisms most likely localized within lateral portions of each cerebellar hemisphere. Reduced timing variability during simultaneous bimanual tasks implies that both timing signals are integrated prior to movement execution, probably by information transfer between both cerebellar hemispheres. However, this raises the question for functional and anatomic fundamentals of such an integration process. The present article reviews behavioural, functional, and anatomic data to shed light on possible interactions between both cerebellar hemispheres during the execution of timed motor behaviour.
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Affiliation(s)
- Bettina Pollok
- Department of Neurology, Heinrich Heine University, Duesseldorf, Germany.
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Bosco G, Eian J, Poppele RE. Phase-specific sensory representations in spinocerebellar activity during stepping: evidence for a hybrid kinematic/kinetic framework. Exp Brain Res 2006; 175:83-96. [PMID: 16733704 DOI: 10.1007/s00221-006-0530-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
The dorsal spinocerebellar tract (DSCT) provides a major mossy fiber input to the spinocerebellum, which plays a significant role in the control of posture and locomotion. Recent work from our laboratory has provided evidence that DSCT neurons encode a global representation of hindlimb mechanics during passive limb movements. The framework that most successfully accounts for passive DSCT behavior is kinematics-based having the coordinates of the limb axis, limb-axis length and orientation. Here we examined the responses of DSCT neurons in decerebrate cats as they walked on a moving treadmill and compared them with the responses passive step-like movements of the hindlimb produced manually. We found that DSCT responses to active locomotion were quantitatively different from the responses to kinematically similar passive limb movements on the treadmill. The differences could not be simply accounted for by the difference in limb-axis kinematics in the two conditions, nor could they be accounted for by new or different response components. Instead, differences could be attributed to an increased relative prominence of specific response components occurring during the stance phase of active stepping, which may reflect a difference in the behavior of the sensory receptors and/or of the DSCT circuitry during active stepping. We propose from these results that DSCT neurons encode two global aspects of limb mechanics that are also important in controlling locomotion at the spinal level, namely the orientation angle of the limb axis and limb loading. Although limb-axis length seemed to be an independent predictor of DSCT activity during passive limb movements, we argue that it is not independent of limb loading, which is likely to be proportional to limb length under passive conditions.
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Affiliation(s)
- G Bosco
- Department of Neuroscience, University of Rome Tor Vergata, IRCCS Fondazione Santa Lucia, Rome, Italy
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Dixon KJ, Hilber W, Speare S, Willson ML, Bower AJ, Sherrard RM. Post-lesion transcommissural olivocerebellar reinnervation improves motor function following unilateral pedunculotomy in the neonatal rat. Exp Neurol 2005; 196:254-65. [PMID: 16125176 DOI: 10.1016/j.expneurol.2005.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Revised: 07/01/2005] [Accepted: 07/27/2005] [Indexed: 11/30/2022]
Abstract
In the adult mammalian central nervous system, reinnervation and recovery from trauma are limited. During development, however, post-lesion plasticity may generate alternate paths providing models to investigate reinnervation and repair. Sometimes, these paths are maladaptive, although the relationship between dysfunction and anatomical abnormality remains unknown. After unilateral transection of the neonatal rat olivocerebellar path (pedunculotomy), axons from the remaining inferior olive reinnervate Purkinje cells in the denervated hemicerebellum with appropriate topography and synaptic function. However, whether this new pathway confers beneficial behavioural effects remains unknown. We studied the behavioural sequelae in rats with and without transcommissural reinnervation using righting and vestibular-drop reflexes, simple locomotion (bridge), complex locomotion (wire) and motor coordination (rotarod) tests. In animals pedunculotomised on day 3 (Px3), which develop olivocerebellar reinnervation, dynamic postural adjustments and complex motor skills develop normally, whereas simple gait is broad-based and slightly delayed. In contrast, Px11 animals, which do not develop reinnervation, have delayed maturation of postural reflexes, gait and complex locomotor skills. In addition, when compared to control animals, their performance in locomotory tasks was slower and the complex task impaired. On the rotarod, control and Px3 animals learned to coordinate their gait and walked for longer at 10 and 20 rpm than Px11 animals. These results show that transcommissural olivocerebellar reinnervation is associated with almost normal motor development and the ability to synchronise gait at slow and moderate speeds, i.e. this reinnervation confers significant behavioural function and is therefore truly compensatory.
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Affiliation(s)
- Kirsty J Dixon
- School of Biomedical Science, James Cook University, Australia
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Bosco G, Eian J, Poppele RE. Kinematic and non-kinematic signals transmitted to the cat cerebellum during passive treadmill stepping. Exp Brain Res 2005; 167:394-403. [PMID: 16261337 DOI: 10.1007/s00221-005-0033-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 04/28/2005] [Indexed: 10/25/2022]
Abstract
Previous work from this laboratory has shown that activity in the dorsal spinocerebellar tract (DSCT) relates strongly to global hindlimb kinematics variables during passive displacements of the hindlimb. A linear relationship to limb axis orientation and length variables accounts for most of the response variance for passive limb positioning and movement. Here we extend those observations to more natural movements by examining the information carried by the DSCT during passive stepping movements on a treadmill, and we compare it to information transmitted during passive robot-driven hindlimb movements. Using a principal component analysis approach, we found that a linear relationship between the responses and hindlimb kinematics was comparable across experimental conditions. We also observed systematic non-linearities in this relationship for both types of movement that could be attributed to events corresponding to the touch-down and lift-off phases of the movement. We concluded that proprioceptive information transmitted to the cerebellum by the DSCT during locomotion has at least two major components. One component is associated with limb kinematics (limb orientation) and may be more or less related to the metrics of the step (stride length, for example) or its velocity. The other component is associated with limb length and/or limb loading, and it may signal some aspect of limb stiffness.
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Affiliation(s)
- G Bosco
- Department of Neuroscience, University of Rome, Tor Vergata and IRCCS Fondazione Santa Lucia, Rome, Italy
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Morningstar MW, Pettibon BR, Schlappi H, Schlappi M, Ireland TV. Reflex control of the spine and posture: a review of the literature from a chiropractic perspective. CHIROPRACTIC & OSTEOPATHY 2005; 13:16. [PMID: 16091134 PMCID: PMC1198239 DOI: 10.1186/1746-1340-13-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Accepted: 08/09/2005] [Indexed: 12/26/2022]
Abstract
OBJECTIVE This review details the anatomy and interactions of the postural and somatosensory reflexes. We attempt to identify the important role the nervous system plays in maintaining reflex control of the spine and posture. We also review, illustrate, and discuss how the human vertebral column develops, functions, and adapts to Earth's gravity in an upright position. We identify functional characteristics of the postural reflexes by reporting previous observations of subjects during periods of microgravity or weightlessness. BACKGROUND Historically, chiropractic has centered around the concept that the nervous system controls and regulates all other bodily systems; and that disruption to normal nervous system function can contribute to a wide variety of common ailments. Surprisingly, the chiropractic literature has paid relatively little attention to the importance of neurological regulation of static upright human posture. With so much information available on how posture may affect health and function, we felt it important to review the neuroanatomical structures and pathways responsible for maintaining the spine and posture. Maintenance of static upright posture is regulated by the nervous system through the various postural reflexes. Hence, from a chiropractic standpoint, it is clinically beneficial to understand how the individual postural reflexes work, as it may explain some of the clinical presentations seen in chiropractic practice. METHOD We performed a manual search for available relevant textbooks, and a computer search of the MEDLINE, MANTIS, and Index to Chiropractic Literature databases from 1970 to present, using the following key words and phrases: "posture," "ocular," "vestibular," "cervical facet joint," "afferent," "vestibulocollic," "cervicocollic," "postural reflexes," "spaceflight," "microgravity," "weightlessness," "gravity," "posture," and "postural." Studies were selected if they specifically tested any or all of the postural reflexes either in Earth's gravity or in microgravitational environments. Studies testing the function of each postural component, as well as those discussing postural reflex interactions, were also included in this review. DISCUSSION It is quite apparent from the indexed literature we searched that posture is largely maintained by reflexive, involuntary control. While reflexive components for postural control are found in skin and joint receptors, somatic graviceptors, and baroreceptors throughout the body, much of the reflexive postural control mechanisms are housed, or occur, within the head and neck region primarily. We suggest that the postural reflexes may function in a hierarchical fashion. This hierarchy may well be based on the gravity-dependent or gravity-independent nature of each postural reflex. Some or all of these postural reflexes may contribute to the development of a postural body scheme, a conceptual internal representation of the external environment under normal gravity. This model may be the framework through which the postural reflexes anticipate and adapt to new gravitational environments. CONCLUSION Visual and vestibular input, as well as joint and soft tissue mechanoreceptors, are major players in the regulation of static upright posture. Each of these input sources detects and responds to specific types of postural stimulus and perturbations, and each region has specific pathways by which it communicates with other postural reflexes, as well as higher central nervous system structures. This review of the postural reflex structures and mechanisms adds to the growing body of posture rehabilitation literature relating specifically to chiropractic treatment. Chiropractic interest in these reflexes may enhance the ability of chiropractic physicians to treat and correct global spine and posture disorders. With the knowledge and understanding of these postural reflexes, chiropractors can evaluate spinal configurations not only from a segmental perspective, but can also determine how spinal dysfunction may be the ultimate consequence of maintaining an upright posture in the presence of other postural deficits. These perspectives need to be explored in more detail.
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Affiliation(s)
- Mark W Morningstar
- Director of Research; The Pettibon Institute, 3416-A 57 St Ct NW Gig Harbor, WA 98335, USA; Private practice of chiropractic, 10683 S Saginaw St, Suite B, Grand Blanc, MI 48439, USA
| | - Burl R Pettibon
- Executive Director; The Pettibon Institute, 3416-A 57 St Ct NW Gig Harbor, WA 98335, USA
| | - Heidi Schlappi
- Doctor of Chiropractic Candidate; Palmer College of Chiropractic. 1000 Brady St Davenport, IA 52803, USA
| | - Mark Schlappi
- Doctor of Chiropractic Candidate; Palmer College of Chiropractic. 1000 Brady St Davenport, IA 52803, USA
| | - Trevor V Ireland
- Board of Trustees; Palmer College of Chiropractic. 1000 Brady St Davenport, IA 52803, USA
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Stein RB, Weber DJ, Aoyagi Y, Prochazka A, Wagenaar JBM, Shoham S, Normann RA. Coding of position by simultaneously recorded sensory neurones in the cat dorsal root ganglion. J Physiol 2004; 560:883-96. [PMID: 15331686 PMCID: PMC1665274 DOI: 10.1113/jphysiol.2004.068668] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Muscle, cutaneous and joint afferents continuously signal information about the position and movement of individual joints. How does the nervous system extract more global information, for example about the position of the foot in space? To study this question we used microelectrode arrays to record impulses simultaneously from up to 100 discriminable nerve cells in the L6 and L7 dorsal root ganglia (DRG) of the anaesthetized cat. When the hindlimb was displaced passively with a random trajectory, the firing rate of the neurones could be predicted from a linear sum of positions and velocities in Cartesian (x, y), polar or joint angular coordinates. The process could also be reversed to predict the kinematics of the limb from the firing rates of the neurones with an accuracy of 1-2 cm. Predictions of position and velocity could be combined to give an improved fit to limb position. Decoders trained using random movements successfully predicted cyclic movements and movements in which the limb was displaced from a central point to various positions in the periphery. A small number of highly informative neurones (6-8) could account for over 80% of the variance in position and a similar result was obtained in a realistic limb model. In conclusion, this work illustrates how populations of sensory receptors may encode a sense of limb position and how the firing of even a small number of neurones can be used to decode the position of the limb in space.
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Affiliation(s)
- R B Stein
- Centre for Neuroscience, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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Scott SH. Optimal feedback control and the neural basis of volitional motor control. Nat Rev Neurosci 2004; 5:532-46. [PMID: 15208695 DOI: 10.1038/nrn1427] [Citation(s) in RCA: 578] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Stephen H Scott
- Department of Anatomy and Cell Biology, Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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