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Papitsa A, Paizis C, Papaiordanidou M, Martin A. Specific modulation of presynaptic and recurrent inhibition of the soleus muscle during lengthening and shortening submaximal and maximal contractions. J Appl Physiol (1985) 2022; 133:1327-1340. [PMID: 36356258 DOI: 10.1152/japplphysiol.00065.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The study analyzed neural mechanisms mediating spinal excitability modulation during eccentric (ECC) movement (passive muscle lengthening, submaximal, and maximal ECC contractions) as compared with concentric (CON) conditions. Twenty-two healthy subjects participated in three experiments. Experiment A (n = 13) examined D1 presynaptic inhibition (D1 PI) and recurrent inhibition (RI) modulation during passive muscle lengthening and shortening, by conditioning the soleus (SOL) H-reflex with common peroneal nerve submaximal and tibial nerve maximal stimulation, respectively. Experiment B (n = 13) analyzed the effect of passive muscle lengthening on D1 PI and heteronymous Ia facilitation (HF, conditioning the SOL H-reflex by femoral stimulation). Experiment C (n = 13) focused on the effect of muscle contraction level (20%, 50%, and 100% of maximal voluntary contraction) on D1 PI and RI. Results showed a significantly higher level of D1 PI during passive muscle lengthening than shortening (P < 0.01), whereas RI and HF were not affected by passive muscle movement. D1 PI and RI were both higher during ECC as compared with CON contractions (P < 0.001). However, the amount of D1 PI was independent of the torque level, whereas RI was reduced as the torque level increased (P < 0.05). The decreased spinal excitability induced by muscle lengthening during both passive and active conditions is mainly attributed to D1 PI, whereas RI also plays a role in the control of the specific motoneuron output during ECC contractions. Both inhibitory mechanisms are centrally controlled, but the fact that they evolve differently with torque increases, suggests a distinct supraspinal control.NEW & NOTEWORTHY Presynaptic (PI) and recurrent inhibitions (RI) were studied during passive muscle lengthening and eccentric contractions. Results indicate that the increased PI during passive muscle lengthening accounts for the decreased spinal excitability at rest. During eccentric contraction both mechanisms contribute to spinal excitability modulation. The same amount of PI was observed during eccentric contractions, while RI decreased as developed torque increased. This distinct modulation according to torque level suggests a distinct supraspinal control of these mechanisms.
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Affiliation(s)
- Athina Papitsa
- Department of Physical Education and Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki Greece
| | - Christos Paizis
- Faculty of Sport Sciences, CAPS, INSERM U1093, University of Bourgogne Franche-Comté, Dijon, France.,Faculty of Sport Sciences, Centre for Performance Expertise, CAPS, U1093 INSERM, University of Bourgogne Franche-Comté, Dijon, France
| | - Maria Papaiordanidou
- Faculty of Sport Sciences, CAPS, INSERM U1093, University of Bourgogne Franche-Comté, Dijon, France
| | - Alain Martin
- Faculty of Sport Sciences, CAPS, INSERM U1093, University of Bourgogne Franche-Comté, Dijon, France
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Grosprêtre S, Lebon F, Papaxanthis C, Martin A. Spinal plasticity with motor imagery practice. J Physiol 2018; 597:921-934. [PMID: 30417924 DOI: 10.1113/jp276694] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/09/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS While a consensus has now been reached on the effect of motor imagery (MI) - the mental simulation of an action - on motor cortical areas, less is known about its impact on spinal structures. The current study, using H-reflex conditioning paradigms, examined the effect of a 20 min MI practice on several spinal mechanisms of the plantar flexor muscles. We observed modulations of spinal presynaptic circuitry while imagining, which was even more pronounced following an acute session of MI practice. We suggested that the small cortical output generated during MI may reach specific spinal circuits and that repeating MI may increase the sensitivity of the spinal cord to its effects. The short-term plasticity induced by MI practice may include spinal network modulation in addition to cortical reorganization. ABSTRACT Kinesthetic motor imagery (MI) is the mental simulation of a movement with its sensory consequences but without its concomitant execution. While the effect of MI practice on cortical areas is well known, its influence on spinal circuitry remains unclear. Here, we assessed plastic changes in spinal structures following an acute MI practice. Thirteen young healthy participants accomplished two experimental sessions: a 20 min MI training consisting of four blocks of 25 imagined maximal isometric plantar flexions, and a 20 min rest (control session). The level of spinal presynaptic inhibition was assessed by conditioning the triceps surae spinal H-reflex with two methods: (i) the stimulation of the common peroneal nerve that induced D1 presynaptic inhibition (HPSI response), and (ii) the stimulation of the femoral nerve that induced heteronymous Ia facilitation (HFAC response). We then compared the effects of MI on unconditioned (HTEST ) and conditioned (HPSI and HFAC ) responses before, immediately after and 10 min after the 20 min session. After resting for 20 min, no changes were observed on the recorded parameters. After MI practice, the amplitude of rest HTEST was unchanged, while HPSI and HFAC significantly increased, showing a reduction of presynaptic inhibition with no impact on the afferent-motoneuronal synapse. The current results revealed the acute effect of MI practice on baseline spinal presynaptic inhibition, increasing the sensitivity of the spinal circuitry to MI. These findings will help in understanding the mechanisms of neural plasticity following chronic practice.
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Affiliation(s)
- Sidney Grosprêtre
- EA4660-C3S Laboratory - Culture, Sport, Health and Society, University of Bourgogne Franche-Comté, Besançon, France
| | - Florent Lebon
- CAPS, U1093 INSERM, Université de Bourgogne Franche-Comté, Facultés des Sciences du Sport, F-21078, Dijon, France
| | - Charalambos Papaxanthis
- CAPS, U1093 INSERM, Université de Bourgogne Franche-Comté, Facultés des Sciences du Sport, F-21078, Dijon, France
| | - Alain Martin
- CAPS, U1093 INSERM, Université de Bourgogne Franche-Comté, Facultés des Sciences du Sport, F-21078, Dijon, France
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Zelenin PV, Lyalka VF, Orlovsky GN, Deliagina TG. Effect of acute lateral hemisection of the spinal cord on spinal neurons of postural networks. Neuroscience 2016; 339:235-253. [PMID: 27702647 PMCID: PMC5118056 DOI: 10.1016/j.neuroscience.2016.09.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 08/10/2016] [Accepted: 09/25/2016] [Indexed: 01/24/2023]
Abstract
In quadrupeds, acute lateral hemisection of the spinal cord (LHS) severely impairs postural functions, which recover over time. Postural limb reflexes (PLRs) represent a substantial component of postural corrections in intact animals. The aim of the present study was to characterize the effects of acute LHS on two populations of spinal neurons (F and E) mediating PLRs. For this purpose, in decerebrate rabbits, responses of individual neurons from L5 to stimulation causing PLRs were recorded before and during reversible LHS (caused by temporal cold block of signal transmission in lateral spinal pathways at L1), as well as after acute surgical LHS at L1. Results obtained after Sur-LHS were compared to control data obtained in our previous study. We found that acute LHS caused disappearance of PLRs on the affected side. It also changed a proportion of different types of neurons on that side. A significant decrease and increase in the proportion of F- and non-modulated neurons, respectively, was found. LHS caused a significant decrease in most parameters of activity in F-neurons located in the ventral horn on the lesioned side and in E-neurons of the dorsal horn on both sides. These changes were caused by a significant decrease in the efficacy of posture-related sensory input from the ipsilateral limb to F-neurons, and from the contralateral limb to both F- and E-neurons. These distortions in operation of postural networks underlie the impairment of postural control after acute LHS, and represent a starting point for the subsequent recovery of postural functions.
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Affiliation(s)
- P V Zelenin
- Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden
| | - V F Lyalka
- Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden
| | - G N Orlovsky
- Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden
| | - T G Deliagina
- Department of Neuroscience, Karolinska Institute, SE-17177 Stockholm, Sweden.
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Grosprêtre S, Lebon F, Papaxanthis C, Martin A. New evidence of corticospinal network modulation induced by motor imagery. J Neurophysiol 2015; 115:1279-88. [PMID: 26719089 DOI: 10.1152/jn.00952.2015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/11/2015] [Indexed: 02/01/2023] Open
Abstract
Motor imagery (MI) is the mental simulation of movement, without the corresponding muscle contraction. Whereas the activation of cortical motor areas during MI is established, the involvement of spinal structures is still under debate. We used original and complementary techniques to probe the influence of MI on spinal structures. Amplitude of motor-evoked potentials (MEPs), cervico-medullary-evoked potentials (CMEPs), and Hoffmann (H)-reflexes of the flexor carpi radialis (FCR) muscle and of the triceps surae muscles was measured in young, healthy subjects at rest and during MI. Participants were asked to imagine maximal voluntary contraction of the wrist and ankle, while the targeted limb was fixed (static condition). We confirmed previous studies with an increase of FCR MEPs during MI compared with rest. Interestingly, CMEPs, but not H-reflexes, also increased during MI, revealing a possible activation of subcortical structures. Then, to investigate the effect of MI on the spinal network, we used two techniques: 1) passive lengthening of the targeted muscle via an isokinetic dynamometer and 2) conditioning of H-reflexes with stimulation of the antagonistic nerve. Both techniques activate spinal inhibitory presynaptic circuitry, reducing the H-reflex amplitude at rest. In contrast, no reduction of H-reflex amplitude was observed during MI. These findings suggest that MI has modulatory effects on the spinal neuronal network. Specifically, the activation of low-threshold spinal structures during specific conditions (lengthening and H-reflex conditioning) highlights the possible generation of subliminal cortical output during MI.
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Affiliation(s)
- Sidney Grosprêtre
- Institut National de la Santé et de la Recherche Médicale U1093, Faculté des sciences du sport, Dijon, France; and Université de Bourgogne Franche-Comté, Besançon, France
| | - Florent Lebon
- Institut National de la Santé et de la Recherche Médicale U1093, Faculté des sciences du sport, Dijon, France; and Université de Bourgogne Franche-Comté, Besançon, France
| | - Charalambos Papaxanthis
- Institut National de la Santé et de la Recherche Médicale U1093, Faculté des sciences du sport, Dijon, France; and Université de Bourgogne Franche-Comté, Besançon, France
| | - Alain Martin
- Institut National de la Santé et de la Recherche Médicale U1093, Faculté des sciences du sport, Dijon, France; and Université de Bourgogne Franche-Comté, Besançon, France
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Matthews CC, Fishman PS, Wittenberg GF. Tetanus toxin reduces local and descending regulation of the H-reflex. Muscle Nerve 2014; 49:495-501. [PMID: 24772492 DOI: 10.1002/mus.23938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Skeletal muscles that are under the influence of tetanus toxin show an exaggerated reflex response to stretch. We examined which changes in the stretch reflex may underlie the exaggerated response. METHODS H-reflexes were obtained from the tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles in rats 7 days after intramuscular injection of tetanus toxin into the TA. RESULTS We found effects of the toxin on the threshold, amplitude, and duration of H-waves from the TA. The toxin inhibited rate-dependent depression in the FDB between the stimulation frequencies of 0.5–50 HZ and when a conditioning magnetic stimulus applied to the brain preceded a test electrical stimulus delivered to the plantar nerve. CONCLUSIONS Tetanus toxin increased the amplitude of the Hwave and reduced the normal depression of H-wave amplitude that is associated with closely timed stimuli, two phenomena that could contribute to hyperactivity of the stretch reflex.
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Grosprêtre S, Papaxanthis C, Martin A. Modulation of spinal excitability by a sub-threshold stimulation of M1 area during muscle lengthening. Neuroscience 2014; 263:60-71. [DOI: 10.1016/j.neuroscience.2014.01.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 12/16/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022]
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Abstract
Postural limb reflexes (PLRs) represent a substantial component of the postural system responsible for stabilization of dorsal-side-up trunk orientation in quadrupeds. Spinalization causes spinal shock, that is a dramatic reduction of extensor tone and spinal reflexes, including PLRs. The goal of our study was to determine changes in activity of spinal interneurons, in particular those mediating PLRs, that is caused by spinalization. For this purpose, in decerebrate rabbits, activity of individual interneurons from L5 was recorded during stimulation causing PLRs under two conditions: (1) when neurons received supraspinal influences and (2) when these influences were temporarily abolished by a cold block of spike propagation in spinal pathways at T12 ("reversible spinalization"; RS). The effect of RS, that is a dramatic reduction of PLRs, was similar to the effect of surgical spinalization. In the examined population of interneurons (n = 199), activity of 84% of them correlated with PLRs, suggesting that they contribute to PLR generation. RS affected differently individual neurons: the mean frequency decreased in 67% of neurons, increased in 15%, and did not change in 18%. Neurons with different RS effects were differently distributed across the spinal cord: 80% of inactivated neurons were located in the intermediate area and ventral horn, whereas 50% of nonaffected neurons were located in the dorsal horn. We found a group of neurons that were coactivated with extensors during PLRs before RS and exhibited a dramatic (>80%) decrease in their activity during RS. We suggest that these neurons are responsible for reduction of extensor tone and postural reflexes during spinal shock.
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Onushko T, Hyngstrom A, Schmit BD. Bilateral oscillatory hip movements induce windup of multijoint lower extremity spastic reflexes in chronic spinal cord injury. J Neurophysiol 2011; 106:1652-61. [PMID: 21753029 DOI: 10.1152/jn.00859.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
After spinal cord injury (SCI), alterations in intrinsic motoneuron properties have been shown to be partly responsible for spastic reflex behaviors in human SCI. In particular, a dysregulation of voltage-dependent depolarizing persistent inward currents (PICs) may permit sustained muscle contraction after the removal of a brief excitatory stimulus. Windup, in which the motor response increases with repeated activation, is an indicator of PICs. Although windup of homonymous stretch reflexes has been shown, multijoint muscle activity is often observed following imposed limb movements and may exhibit a similar windup phenomenon. The purpose of this study was to identify and quantify windup of multijoint reflex responses to repeated imposed hip oscillations. Ten chronic SCI subjects participated in this study. A custom-built servomotor apparatus was used to oscillate the legs about the hip joint bilaterally and unilaterally from 10° of extension to 40° flexion for 10 consecutive cycles. Surface electromyograms (EMGs) and joint torques were recorded from both legs. Consistent with a windup response, hip and knee flexion/extension and ankle plantarflexion torque and EMG responses varied according to movement cycle number. The temporal patterns of windup depended on the muscle groups that were activated, which may suggest a difference in the response of neurons in different spinal pathways. Furthermore, because windup was seen in muscles that were not being stretched, these results imply that changes in interneuronal properties are also likely to be associated with windup of spastic reflexes in human SCI.
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Affiliation(s)
- Tanya Onushko
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
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Chen XY, Chen L, Chen Y, Wolpaw JR. Operant Conditioning of Reciprocal Inhibition in Rat Soleus Muscle. J Neurophysiol 2006; 96:2144-50. [PMID: 16807351 DOI: 10.1152/jn.00253.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), induces activity-dependent plasticity in the spinal cord and might be used to improve locomotion after spinal cord injury. To further assess the potential clinical significance of spinal reflex conditioning, this study asks whether another well-defined spinal reflex pathway, the disynaptic pathway underlying reciprocal inhibition (RI), can also be operantly conditioned. Sprague-Dawley rats were implanted with electromyographic (EMG) electrodes in right soleus (SOL) and tibialis anterior (TA) muscles and a stimulating cuff on the common peroneal (CP) nerve. When background EMG in both muscles remained in defined ranges, CP stimulation elicited the TA H-reflex and SOL RI. After collection of control data for 20 days, each rat was exposed for 50 days to up-conditioning (RIup mode) or down-conditioning (RIdown mode) in which food reward occurred if SOL RI evoked by CP stimulation was more (RIup mode) or less (RIdown mode) than a criterion. TA and SOL background EMG and TA M response remained stable. In every rat, RI conditioning was successful (i.e., change ≥20% in the correct direction). In the RIup rats, final SOL RI averaged 171± 28% (mean ± SE) of control, and final TA H-reflex averaged 114 ± 14%. In the RIdown rats, final SOL RI averaged 37 ± 13% of control, and final TA H-reflex averaged 60 ± 18%. Final SOL RI and TA H-reflex sizes were significantly correlated. Thus like the SSR and the H-reflex, RI can be operantly conditioned; and conditioning one reflex can affect another reflex as well.
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Affiliation(s)
- Xiang Yang Chen
- Wadsworth Center, Laboratory of Nervous System Disorders, New York State Department of Health and State University of New York, Albany, New York 12201-0509, USA.
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Repetitive Sensory Input Increases Reciprocal Ia Inhibition In Individuals With Incomplete Spinal Cord Injury. J Neurol Phys Ther 2004. [DOI: 10.1097/01253086-200409000-00003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Westad C, Westgaard RH, De Luca CJ. Motor unit recruitment and derecruitment induced by brief increase in contraction amplitude of the human trapezius muscle. J Physiol 2004; 552:645-56. [PMID: 14561844 PMCID: PMC2343389 DOI: 10.1113/jphysiol.2003.044990] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The activity pattern of low-threshold human trapezius motor units was examined in response to brief, voluntary increases in contraction amplitude ('EMG pulse') superimposed on a constant contraction at 4-7 % of the surface electromyographic (EMG) response at maximal voluntary contraction (4-7 % EMGmax). EMG pulses at 15-20 % EMGmax were superimposed every minute on contractions of 5, 10, or 30 min duration. A quadrifilar fine-wire electrode recorded single motor unit activity and a surface electrode recorded simultaneously the surface EMG signal. Low-threshold motor units recruited at the start of the contraction were observed to stop firing while motor units of higher recruitment threshold stayed active. Derecruitment of a motor unit coincided with the end of an EMG pulse. The lowest-threshold motor units showed only brief silent periods. Some motor units with recruitment threshold up to 5 % EMGmax higher than the constant contraction level were recruited during an EMG pulse and kept firing throughout the contraction. Following an EMG pulse, there was a marked reduction in motor unit firing rates upon return of the surface EMG signal to the constant contraction level, outlasting the EMG pulse by 4 s on average. The reduction in firing rates may serve as a trigger to induce derecruitment. We speculate that the silent periods following derecruitment may be due to deactivation of non-inactivating inward current ('plateau potentials'). The firing behaviour of trapezius motor units in these experiments may thus illustrate a mechanism and a control strategy to reduce fatigue of motor units with sustained activity patterns.
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Affiliation(s)
- C Westad
- Department of Industrial Economics and Technology Management, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
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Perez MA, Field-Fote EC. Impaired posture-dependent modulation of disynaptic reciprocal Ia inhibition in individuals with incomplete spinal cord injury. Neurosci Lett 2003; 341:225-8. [PMID: 12697289 DOI: 10.1016/s0304-3940(03)00183-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Posture influences the strength of spinal reflex circuits in healthy individuals. The purpose of this study was to determine the extent to which sitting and standing posture influences the strength of reciprocal Ia inhibition between ankle flexor and extensor muscles in individuals with incomplete spinal cord injury (SCI). Ten individuals with SCI and 15 healthy individuals participated in the study. Short-latency reciprocal inhibition was measured by conditioning the soleus H-reflex with stimulation of the common peroneal nerve. There was no significant difference in the strength of reciprocal Ia inhibition in sitting and standing positions in individuals with SCI. However, healthy individuals showed increased inhibition in a standing compared to a sitting position. The results suggest an impaired posture-dependent modulation of reciprocal Ia inhibition following SCI.
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Affiliation(s)
- Monica A Perez
- Department of Orthopedics and Rehabilitation, Division of Physical Therapy, University of Miami School of Medicine, FL 33136, USA
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Hornby TG, Rymer WZ, Benz EN, Schmit BD. Windup of flexion reflexes in chronic human spinal cord injury: a marker for neuronal plateau potentials? J Neurophysiol 2003; 89:416-26. [PMID: 12522190 DOI: 10.1152/jn.00979.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The physiological basis of flexion spasms in individuals after spinal cord injury (SCI) may involve alterations in the properties of spinal neurons in the flexion reflex pathways. We hypothesize that these changes would be manifested as progressive increases in reflex response with repetitive stimulus application (i.e., "windup") of the flexion reflexes. We investigated the windup of flexion reflex responses in 12 individuals with complete chronic SCI. Flexion reflexes were triggered using trains of electrical stimulation of plantar skin at variable intensities and inter-stimulus intervals. For threshold and suprathreshold stimulation, windup of both peak ankle and hip flexion torques and of integrated tibialis anterior electromyographic activity was observed consistently in all patients at inter-stimulus intervals < or =3 s. For subthreshold stimuli, facilitation of reflexes occurred only at intervals < or =1 s. Similarly, the latency of flexion reflexes decreased significantly at intervals < or =1 s. Patients that were receiving anti-spasticity medications (e.g., baclofen) had surprisingly larger windup of reflex responses than those who did not take such medications, although this difference may be related to differences of spasm frequency between the groups of subjects. The results indicate that the increase in spinal neuronal excitability following a train of electrical stimuli lasts for < or =3 s, similar to previous studies of nociceptive processing. Such long-lasting increases in flexion reflex responses suggest that cellular mechanisms such as plateau potentials in spinal motoneurons, interneurons, or both, may partially mediate spinal cord hyperexcitability in the absence of descending modulatory input.
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Affiliation(s)
- T G Hornby
- Department of Physical Medicine and Rehabilitation, Northwestern University Medical School, Chicago, IL 60611, USA.
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de Louw AJA, de Vente J, Steinbusch HPJ, Gavilanes AWD, Steinbusch HWM, Blanco CE, Troost J, Vles JSH. Apoptosis in the rat spinal cord during postnatal development; the effect of perinatal asphyxia on programmed cell death. Neuroscience 2002; 112:751-8. [PMID: 12088735 DOI: 10.1016/s0306-4522(02)00134-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of our study was to investigate the effect of perinatal asphyxia on developmental apoptosis in the cervical and lumbar spinal cord in the neonatal rat. Perinatal asphyxia was induced by keeping pups at term in utero in a water bath at 37 degrees C for 20 min, followed by resuscitation. Effects of this treatment on developmental apoptosis were studied on postnatal days 2, 5 and 8 using terminal deoxynucleotidyl transferase (TdT)-dUTP-biotin nick end labelling (TUNEL) and caspase-3 staining. TUNEL positive cells were identified using double immunostaining. On postnatal day 2 an increase of 215% in TUNEL positive cells was detected (P=0.005) in laminae IV-VII of the lumbar spinal cord of rats which underwent perinatal asphyxia compared to controls. An increase of 55% compared to controls (P=0.03) was seen in laminae I-III of the lumbar spinal cord at postnatal day 8. TUNEL positive cells could be partly identified as microglia cells (ED1 positive) and oligodendrocytes (O4 positive). The effect of perinatal asphyxia on programmed cell death in the neonatal rat spinal cord was mainly observed in the intermediate zone and dorsal horn of the lumbar spinal cord. We conclude that perinatal asphyxia has a pronounced effect on the survival of cells in a specific region of the spinal cord and thus may have a profound effect on the development of motor networks.
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Affiliation(s)
- A J A de Louw
- Department of Neurology, Academic Hospital Maastricht, P.O. Box 5800, The Netherlands.
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