1
|
Li S, Triolo RJ, Charkhkar H. Neural sensory stimulation does not interfere with the H-reflex in individuals with lower limb amputation. Front Neurosci 2023; 17:1276308. [PMID: 37817801 PMCID: PMC10560717 DOI: 10.3389/fnins.2023.1276308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/12/2023] [Indexed: 10/12/2023] Open
Abstract
Introduction Individuals with lower limb loss experience an increased risk of falls partly due to the lack of sensory feedback from their missing foot. It is possible to restore plantar sensation perceived as originating from the missing foot by directly interfacing with the peripheral nerves remaining in the residual limb, which in turn has shown promise in improving gait and balance. However, it is yet unclear how these electrically elicited plantar sensation are integrated into the body's natural sensorimotor control reflexes. Historically, the H-reflex has been used as a model for investigating sensorimotor control. Within the spinal cord, an array of inputs, including plantar cutaneous sensation, are integrated to produce inhibitory and excitatory effects on the H-reflex. Methods In this study, we characterized the interplay between electrically elicited plantar sensations and this intrinsic reflex mechanism. Participants adopted postures mimicking specific phases of the gait cycle. During each posture, we electrically elicited plantar sensation, and subsequently the H-reflex was evoked both in the presence and absence of these sensations. Results Our findings indicated that electrically elicited plantar sensations did not significantly alter the H-reflex excitability across any of the adopted postures. Conclusion This suggests that individuals with lower limb loss can directly benefit from electrically elicited plantar sensation during walking without disrupting the existing sensory signaling pathways that modulate reflex responses.
Collapse
Affiliation(s)
- Suzhou Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland Veteran Affairs Medical Center, Cleveland, OH, United States
| | - Ronald J. Triolo
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland Veteran Affairs Medical Center, Cleveland, OH, United States
| | - Hamid Charkhkar
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland Veteran Affairs Medical Center, Cleveland, OH, United States
| |
Collapse
|
2
|
F-waves induced by motor point stimulation are facilitated during handgrip and motor imagery tasks. Exp Brain Res 2023; 241:527-537. [PMID: 36622384 DOI: 10.1007/s00221-022-06537-x] [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: 07/27/2022] [Accepted: 12/21/2022] [Indexed: 01/10/2023]
Abstract
The F-wave is a motor response elicited via the antidromic firings of motor nerves by the electrical stimulation of peripheral nerves, which reflects the motoneuron pool excitability. However, the F-wave generally has low robustness i.e., low persistence and small amplitude. We recently found that motor point stimulation (MPS), which provides the muscle belly with electrical stimulation, shows different neural responses compared to nerve stimulation, e.g., MPS elicits F-waves more robustly than nerve stimulation. Here, we investigated whether F-waves induced by MPS can identify changes in motoneuron pool excitability during handgrip and motor imagery. Twelve participants participated in the present study. We applied MPS on their soleus muscle and recorded F-waves during eyes-open (EO), eyes-closed (EC), handgrip (HG), and motor imagery (MI) conditions. In the EO and EC conditions, participants relaxed with their eyes open and closed, respectively. In the HG, participants matched the handgrip force level to 30% of the maximum voluntary force with visual feedback. In the MI, they performed kinesthetic MI of plantarflexion at the maximal strength with closed eyes. In the HG and MI, the amplitudes of the F-waves induced by MPS were increased compared with those in the EO and EC, respectively. These results indicate that the motoneuron pool excitability was facilitated during the HG and MI conditions, consistent with findings in previous studies. Our findings suggest that F-waves elicited by MPS can be a good tool in human neurophysiology to assess the motoneuron pool excitability during cognitive and motor tasks.
Collapse
|
3
|
Hagio S, Ishihara A, Terada M, Tanabe H, Kibushi B, Higashibata A, Yamada S, Furukawa S, Mukai C, Ishioka N, Kouzaki M. Muscle synergies of multi-directional postural control in astronauts on Earth after a long-term stay in space. J Neurophysiol 2022; 127:1230-1239. [PMID: 35353615 DOI: 10.1152/jn.00232.2021] [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: 11/22/2022] Open
Abstract
Movements of the human biological system have adapted to the physical environment under the 1-g gravitational force on Earth. However, the effects of microgravity in space on the underlying functional neuromuscular control behaviors remain poorly understood. Here, we aimed to elucidate the effects of prolonged exposure to a microgravity environment on the functional coordination of multiple muscle activities. The activities of 16 lower limb muscles of 5 astronauts who stayed in space for at least 3 months were recorded while they maintained multidirectional postural control during bipedal standing. The coordinated activation patterns of groups of muscles, i.e., muscle synergies, were estimated from the muscle activation datasets using a factorization algorithm. The experiments were repeated a total of 5 times for each astronaut, once before and 4 times after spaceflight. The compositions of muscle synergies were altered, with a constant number of synergies, after long-term exposure to microgravity, and the extent of the changes was correlated with the severity of the deficits in postural stability. Furthermore, the muscle synergies extracted 3 months after the return were similar in their activation profile but not in their muscle composition compared with those extracted in the preflight condition. These results suggest that the modularity in the neuromuscular system became reorganized to adapt to the microgravity environment and then possibly reoptimized to the new sensorimotor environment after the astronauts were re-exposed to a gravitational force. It is expected that muscle synergies can be used as physiological markers of the status of astronauts with gravity-dependent change.
Collapse
Affiliation(s)
- Shota Hagio
- Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.,Unit of Synergetic Studies for Space, Kyoto University, Kyoto, Japan
| | - Akihiko Ishihara
- Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Masahiro Terada
- Unit of Synergetic Studies for Space, Kyoto University, Kyoto, Japan
| | - Hiroko Tanabe
- Institutes of Innovation for Future Society, Nagoya University, Aichi, Japan
| | - Benio Kibushi
- Faculty of Sport Science, Waseda University, Saitama, Japan
| | - Akira Higashibata
- Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, Ibaraki, Japan
| | - Shin Yamada
- Graduate School of Medicine, Kyorin University, Tokyo, Japan
| | - Satoshi Furukawa
- Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, Ibaraki, Japan
| | - Chiaki Mukai
- Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, Ibaraki, Japan
| | - Noriaki Ishioka
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa, Japan
| | - Motoki Kouzaki
- Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.,Unit of Synergetic Studies for Space, Kyoto University, Kyoto, Japan
| |
Collapse
|
4
|
Kaneko N, Fok KL, Nakazawa K, Masani K. Motor point stimulation induces more robust F-waves than peripheral nerve stimulation. Eur J Neurosci 2022; 55:1614-1628. [PMID: 35178805 DOI: 10.1111/ejn.15625] [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: 08/20/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 11/27/2022]
Abstract
The F-wave is a motor response induced by electrical stimulation of peripheral nerves via the antidromic firing of motor nerves, which reflects the motoneuron excitability. To induce F-waves, transcutaneous peripheral nerve stimulation (PNS) is used, which activates nerve branches via transcutaneous electrodes over the nerve branches. An alternative method to activate peripheral nerves, i.e., motor point stimulation (MPS) which delivers electrical stimulation over the muscle belly, has not been used to induce F-waves. In our previous studies, we observed that MPS induced F-wave like responses, i.e., motor responses at the latency of F-waves at a supramaximal stimulation. Here we further investigated the F-wave like responses induced by MPS in comparison to PNS in the soleus muscle. Thirteen individuals participated in this study. We applied MPS and PNS on the participant's left soleus muscle. Using a monopolar double-pulse stimulation, the amplitude of the second H-reflex induced by PNS decreased, while the amplitude of the motor response at the F-wave latency induced by MPS did not decrease. These results suggest that the motor response at the F-wave latency induced by MPS was not an H-reflex but an F-wave. We also found that the F-wave induced by MPS had a greater amplitude, higher persistence, and caused less pain when compared to the F-waves induced using PNS. We conclude that MPS evokes antidromic firing inducing F-waves more consistently compared to PNS.
Collapse
Affiliation(s)
- Naotsugu Kaneko
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,KITE - Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kai Lon Fok
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,KITE - Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada
| | - Kimitaka Nakazawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kei Masani
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,KITE - Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada
| |
Collapse
|
5
|
Megía-García Á, Serrano-Muñoz D, Comino-Suárez N, Del-Ama AJ, Moreno JC, Gil-Agudo A, Taylor J, Gómez-Soriano J. Effect of posture and body weight loading on spinal posterior root reflex responses. Eur J Neurosci 2021; 54:6575-6586. [PMID: 34494329 DOI: 10.1111/ejn.15448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 09/02/2021] [Accepted: 09/02/2021] [Indexed: 11/30/2022]
Abstract
The posterior root muscle response (PRM) is a monosynaptic reflex that is evoked by single pulse transcutaneous spinal cord stimulation (tSCS). The main aim of this work was to analyse how body weight loading influences PRM reflex threshold measured from several lower limb muscles in healthy participants. PRM reflex responses were evoked with 1-ms rectangular monophasic pulses applied at an interval of 6 s via a self-adhesive electrode (9 × 5 cm) at the T11-T12 vertebral level. Surface electromyographic activity of lower limb muscles was recorded during four different conditions, one in decubitus supine (DS) and the other three involving standing at 100%, 50%, and 0% body weight loading (BW). PRM threshold intensity, peak-to-peak amplitude, and latency for each muscle were analysed in different conditions study. PRM reflex threshold increased with body weight unloading compared with DS, and the largest change was observed between DS and 0% BW for the proximal muscles and between DS and 50% BW for distal muscles. Peak-to-peak amplitude analysis showed only a significant mean decrease of 34.6% (SD 10.4, p = 0.028) in TA and 53.6% (SD 15.1, p = 0.019) in GM muscles between DS and 50% BW. No significant differences were observed for PRM latency. This study has shown that sensorimotor networks can be activated with tSCS in various conditions of body weight unloading. Higher stimulus intensities are necessary to evoke reflex response during standing at 50% body weight loading. These results have practical implications for gait rehabilitation training programmes that include body weight support.
Collapse
Affiliation(s)
- Álvaro Megía-García
- Biomechanical and Technical Aids Unit, National Hospital for Paraplegia, SESCAM, Toledo, Spain.,Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing, Castilla La Mancha University, Toledo, Spain
| | - Diego Serrano-Muñoz
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing, Castilla La Mancha University, Toledo, Spain
| | - Natalia Comino-Suárez
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain
| | - Antonio J Del-Ama
- Biomechanical and Technical Aids Unit, National Hospital for Paraplegia, SESCAM, Toledo, Spain.,Rey Juan Carlos University, Madrid, Spain
| | - Juan C Moreno
- Neural Rehabilitation Group, Cajal Institute, Spanish National Research Council (CSIC), Madrid, Spain
| | - Angel Gil-Agudo
- Biomechanical and Technical Aids Unit, National Hospital for Paraplegia, SESCAM, Toledo, Spain
| | - Julian Taylor
- Sensorimotor Function Group, National Hospital for Paraplegia, SESCAM, Toledo, Spain.,Harris Manchester College, University of Oxford, Oxford, UK
| | - Julio Gómez-Soriano
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing, Castilla La Mancha University, Toledo, Spain
| |
Collapse
|
6
|
Dutt-Mazumder A, Segal RL, Thompson AK. Effect of Ankle Angles on the Soleus H-Reflex Excitability During Standing. Motor Control 2020; 24:189-203. [PMID: 31899887 PMCID: PMC7329593 DOI: 10.1123/mc.2018-0118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022]
Abstract
This study investigated effects of ankle joint angle on the Hoffman's reflex (H-reflex) excitability during loaded (weight borne with both legs) and unloaded (full body weight borne with the contralateral leg) standing in people without neurological injuries. Soleus H-reflex/M-wave recruitment curves were examined during upright standing on three different slopes that imposed plantar flexion (-15°), dorsiflexion (+15°), and neutral (0°) angles at the ankle, with the test leg loaded and unloaded. With the leg loaded and unloaded, maximum H-reflex/maximum M-wave ratio of -15° was significantly larger than those of 0° and +15° conditions. The maximum H-reflex/maximum M-wave ratios were 51%, 43%, and 41% with loaded and 56%, 46%, and 44% with unloaded for -15°, 0°, and +15° slope conditions, respectively. Thus, limb loading/unloading had limited impact on the extent of influence that ankle angles exert on the H-reflex excitability. This suggests that task-dependent central nervous system control of reflex excitability may regulate the influence of sensory input on the spinal reflex during standing.
Collapse
|
7
|
Ritzmann R, Freyler K, Helm M, Holubarsch J, Gollhofer A. Stumbling Reactions in Partial Gravity - Neuromechanics of Compensatory Postural Responses and Inter-Limb Coordination During Perturbation of Human Stance. Front Physiol 2019; 10:576. [PMID: 31164834 PMCID: PMC6536696 DOI: 10.3389/fphys.2019.00576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/24/2019] [Indexed: 02/05/2023] Open
Abstract
Spontaneous changes in gravity play a significant role in interplanetary space missions. To preserve the astronauts’ capability to execute mission-critical tasks and reduce the risk of injury in transit and on planetary surfaces, a comprehensive understanding of the neuromuscular control of postural responses after balance deterioration in hypo- or hyper-gravity conditions is essential. Therefore, this study aimed to evaluate the effect of acute gravitational variation on postural adjustments in response to perturbations. Gravitational changes were induced using parabolic flight. Postural set was manipulated by randomly providing unilateral left, bilateral or split perturbations which require balance corrections to restore postural stability. In six subjects, postural reactions were recorded after anterior and posterior surface perturbations for progressively increased gravitational conditions spanning from 0.25 to 1.75 g. Ankle and knee joint kinematics and electromyograms (EMG) of eight leg muscles were recorded prior (PRE) and after perturbation onset. Muscle activation onset latencies and amplitudes in the short-, medium-, and long-latency responses (SLR, MLR, LLR) were assessed. Results demonstrate an increased muscle activity (p < 0.05) and co-contraction in the lower extremities (p < 0.05) prior to perturbation in hypo- and hyper-gravity. After perturbation, reduced muscle onset latencies (p < 0.05) and increased muscle activations in the MLR and LLR (p < 0.05), concomitant with an increased co-contraction in the SLR, were manifested with a progressive rise in gravity. Ankle and knee joint deflections remained unaffected, whereas angular velocities increased (p < 0.05) with increasing gravitation. Effects were more pronounced in bi- compared to unilateral or split perturbations (p < 0.05). Neuro-mechanical adaptations to gravity were more distinct and muscle onset latencies were shorter in the displaced compared to the non-displaced leg. In conclusion, the timing and magnitude of postural reflexes involved in stabilization of bipedal stance are gravity-dependent. The approximately linear relationship between gravity and impulse-directed EMG amplitudes or muscle onset latencies after perturbation indicates that the central nervous system correctly predicts the level of gravity. Moreover, it accurately governs contractions in the antigravity musculature to counterbalance the gravitational pull and to regain upright posture after its disturbance. Importantly, unilateral perturbations evoked fast reflex responses in the synergistic muscles of the non-displaced contralateral leg suggesting a synchronized inter-limb coordination mediated by spinal circuitries.
Collapse
Affiliation(s)
- Ramona Ritzmann
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany.,Praxisklinik Rennbahn AG, Muttenz, Switzerland
| | - Kathrin Freyler
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Michael Helm
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Janek Holubarsch
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Albert Gollhofer
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| |
Collapse
|
8
|
Tseng SC, Shields RK. Limb Segment Load Inhibits the Recovery of Soleus H-Reflex After Segmental Vibration in Humans. J Mot Behav 2017; 50:631-642. [PMID: 29140761 DOI: 10.1080/00222895.2017.1394259] [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: 10/18/2022]
Abstract
We investigated the effects of vertical vibration and compressive load on soleus H-reflex amplitude and postactivation depression. We hypothesized that, in the presence of a compressive load, limb vibration induces a longer suppression of soleus H-reflex. Eleven healthy adults received vibratory stimulation at a fixed frequency (30 Hz) over two loading conditions (0% and 50% of individual's body weight). H-reflex amplitude was depressed ∼88% in both conditions during vibration. Cyclic application of compression after cessation of the vibration caused a persistent reduction in H-reflex excitability and postactivation depression for > 2.5 min. A combination of limb segment vibration and compression may offer a nonpharmacologic method to modulate spinal reflex excitability in people after CNS injury.
Collapse
Affiliation(s)
- Shih-Chiao Tseng
- a School of Physical Therapy , Texas Woman's University , 6700 Fannin, Houston , Texas , USA
| | - Richard K Shields
- b Department of Physical Therapy & Rehabilitation Science , University of Iowa, Carver College of Medicine , Iowa City , Iowa , USA
| |
Collapse
|
9
|
Buettner D, Dalin D, Wiesmeier IK, Maurer C. Virtual Balancing for Studying and Training Postural Control. Front Neurosci 2017; 11:531. [PMID: 29018320 PMCID: PMC5623041 DOI: 10.3389/fnins.2017.00531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/12/2017] [Indexed: 11/13/2022] Open
Abstract
Postural control during free stance has been frequently interpreted in terms of balancing an inverted pendulum. This even holds, if subjects do not balance their own, but an external body weight. We introduce here a virtual balancing apparatus, which produces torque in the ankle joint as a function of ankle angle resembling the gravity and inertial effects of free standing. As a first aim of this study, we systematically modified gravity, damping, and inertia to examine its effect on postural control beyond the physical constraints given in the real world. As a second aim, we compared virtual balancing to free stance to test its suitability for balance training in patients who are not able to balance their full body weight due to certain medical conditions. In a feasibility study, we analyzed postural control during free stance and virtual balancing in 15 healthy subjects. Postural control was characterized by spontaneous sway measures and measures of perturbed stance. During free stance, perturbations were induced by pseudorandom anterior-posterior tilts of the body support surface. In the virtual balancing task, we systematically varied the anterior-posterior position of the foot plate where the balancing forces are zero following a similar pseudorandom stimulus profile. We found that subjects' behavior during virtual balancing resembles free stance on a tilting platform. This specifically holds for the profile of body excursions as a function of stimulus frequencies. Moreover, non-linearity between stimulus and response amplitude is similar in free and virtual balancing. The overall larger stimulus induced body excursions together with an altered phase behavior between stimulus and response could be in part explained by the limited use of vestibular and visual feedback in our experimental setting. Varying gravity or damping significantly affected postural behavior. Inertia as an isolated factor had a mild effect on the response functions. We conclude that virtual balancing may be well suited to simulate conditions which could otherwise only be realized in space experiments or during parabolic flights. Further studies are needed to examine patients' potential benefit of virtual balance training.
Collapse
Affiliation(s)
- Daniela Buettner
- Department of Neurology and Neurophysiology, University Hospital Freiburg, Medical Faculty, Freiburg, Germany
| | - Daniela Dalin
- Department of Neurology and Neurophysiology, University Hospital Freiburg, Medical Faculty, Freiburg, Germany
| | - Isabella K Wiesmeier
- Department of Neurology and Neurophysiology, University Hospital Freiburg, Medical Faculty, Freiburg, Germany
| | - Christoph Maurer
- Department of Neurology and Neurophysiology, University Hospital Freiburg, Medical Faculty, Freiburg, Germany
| |
Collapse
|
10
|
Marinho-Buzelli AR, Rouhani H, Masani K, Verrier MC, Popovic MR. The influence of the aquatic environment on the control of postural sway. Gait Posture 2017; 51:70-76. [PMID: 27710837 DOI: 10.1016/j.gaitpost.2016.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 02/02/2023]
Abstract
Balance training in the aquatic environment is often used in rehabilitation practice to improve static and dynamic balance. Although aquatic therapy is widely used in clinical practice, we still lack evidence on how immersion in water actually impacts postural control. We examined how postural sway measured using centre of pressure and trunk acceleration parameters are influenced by the aquatic environment along with the effects of visual information. Our results suggest that the aquatic environment increases postural instability, measured by the centre of pressure parameters in the time-domain. The mean velocity and area were more significantly affected when individuals stood with eyes closed in the aquatic environment. In addition, a more forward posture was assumed in water with eyes closed in comparison to standing on land. In water, the low frequencies of sway were more dominant compared to standing on dry land. Trunk acceleration differed in water and dry land only for the larger upper trunk acceleration in mediolateral direction during standing in water. This finding shows that the study participants potentially resorted to using their upper trunk to compensate for postural instability in mediolateral direction. Only the lower trunk seemed to change acceleration pattern in anteroposterior and mediolateral directions when the eyes were closed, and it did so depending on the environment conditions. The increased postural instability and the change in postural control strategies that the aquatic environment offers may be a beneficial stimulus for improving balance control.
Collapse
Affiliation(s)
- Andresa R Marinho-Buzelli
- Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada.
| | - Hossein Rouhani
- Department of Mechanical Engineering, University of Alberta, Donadeo Innovation Centre for Engineering, 9211-116 Street NW, Room 10-368, Edmonton, AB, T6G 1H9, Canada.
| | - Kei Masani
- Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 407, Toronto, Ontario, M5S 3G9, Canada.
| | - Mary C Verrier
- Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Department of Physical Therapy, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada.
| | - Milos R Popovic
- Rehabilitation Sciences Institute, University of Toronto, 500 University Avenue, Toronto, ON, M5G 1V7, Canada; Toronto Rehabilitation Institute - University Health Network, Lyndhurst Centre, 520 Sutherland Drive, Toronto, ON, M4G 3V9, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Room 407, Toronto, Ontario, M5S 3G9, Canada.
| |
Collapse
|
11
|
Liang JN, Brown DA. Impaired H-Reflex Gain during Postural Loaded Locomotion in Individuals Post-Stroke. PLoS One 2015; 10:e0144007. [PMID: 26629996 PMCID: PMC4668037 DOI: 10.1371/journal.pone.0144007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 11/06/2015] [Indexed: 11/19/2022] Open
Abstract
Objective Successful execution of upright locomotion requires coordinated interaction between controllers for locomotion and posture. Our earlier research supported this model in the non-impaired and found impaired interaction in the post-stroke nervous system during locomotion. In this study, we sought to examine the role of the Ia afferent spinal loop, via the H-reflex response, under postural influence during a locomotor task. We tested the hypothesis that the ability to increase stretch reflex gain in response to postural loads during locomotion would be reduced post-stroke. Methods Fifteen individuals with chronic post-stroke hemiparesis and 13 non-impaired controls pedaled on a motorized cycle ergometer with specialized backboard support system under (1) seated supported, and (2) non-seated postural-loaded conditions, generating matched pedal force outputs of two levels. H-reflexes were elicited at 90°crank angle. Results We observed increased H-reflex gain with postural influence in non-impaired individuals, but a lack of increase in individuals post-stroke. Furthermore, we observed decreased H-reflex gain at higher postural loads in the stroke-impaired group. Conclusion These findings suggest an impaired Ia afferent pathway potentially underlies the defects in the interaction between postural and locomotor control post-stroke and may explain reduced ability of paretic limb support during locomotor weight-bearing in individuals post-stroke. Significance These results support the judicious use of bodyweight support training when first helping individuals post-stroke to regain locomotor pattern generation and weight-bearing capability.
Collapse
Affiliation(s)
- Jing Nong Liang
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Interdepartmental Neuroscience Program, Feinberg School of Medicine, Northwestern University, Chicago Illinois, United States of America
- Department of Physical Therapy, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
- * E-mail:
| | - David A. Brown
- Department of Physical Therapy, School of Health Related Professions, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| |
Collapse
|
12
|
Ritzmann R, Freyler K, Weltin E, Krause A, Gollhofer A. Load Dependency of Postural Control--Kinematic and Neuromuscular Changes in Response to over and under Load Conditions. PLoS One 2015; 10:e0128400. [PMID: 26053055 PMCID: PMC4459704 DOI: 10.1371/journal.pone.0128400] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 04/28/2015] [Indexed: 11/24/2022] Open
Abstract
Introduction Load variation is associated with changes in joint torque and compensatory reflex activation and thus, has a considerable impact on balance control. Previous studies dealing with over (OL) and under loading (UL) used water buoyancy or additional weight with the side effects of increased friction and inertia, resulting in substantially modified test paradigms. The purpose of this study was to identify gravity-induced load dependency of postural control in comparable experimental conditions and to determine the underlying neuromuscular mechanisms. Methods Balance performance was recorded under normal loading (NL, 1g), UL (0.16g; 0.38g) and OL (1.8g) in monopedal stance. Center of pressure (COP) displacement and frequency distribution (low 0.15-0.5Hz (LF), medium 0.5-2Hz (MF), high 2-6Hz (HF)) as well as ankle, knee and hip joint kinematics were assessed. Soleus spinal excitability was determined by H/M-recruitment curves (H/M-ratios). Results Compared to NL, OL caused an increase in ankle joint excursion, COP HF domain and H/M-ratio. Concomitantly, hip joint excursion and COP LF decreased. Compared to NL, UL caused modulations in the opposite direction: UL decreased ankle joint excursions, COP HF and H/M-ratio. Collaterally, hip joint excursion and COP LF increased. COP was augmented both in UL and in OL compared to NL. Conclusion Subjects achieved postural stability in OL and UL with greater difficulty compared to NL. Reduced postural control was accompanied by modified balance strategies and compensatory reflex activation. With increasing load, a shift from hip to ankle strategy was observed. Accompanying, COP frequency distribution shifted from LF to HF and spinal excitability was enhanced. It is suggested that in OL, augmented ankle joint torques are compensated by quick reflex-induced postural reactions in distal muscles. Contrarily, UL is associated with diminished joint torques and thus, postural equilibrium may be controlled by the proximal segments to adjust the center of gravity above the base of support.
Collapse
Affiliation(s)
- Ramona Ritzmann
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
- * E-mail:
| | - Kathrin Freyler
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Elmar Weltin
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Anne Krause
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| | - Albert Gollhofer
- Institute of Sport and Sport Science, University of Freiburg, Freiburg, Germany
| |
Collapse
|
13
|
Masu Y, Muramatsu K. Soleus H-reflex modulation during receive stance in badminton players in the receive stance. J Phys Ther Sci 2015; 27:123-5. [PMID: 25642054 PMCID: PMC4305541 DOI: 10.1589/jpts.27.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/24/2014] [Indexed: 11/24/2022] Open
Abstract
[Purpose] This study aimed to clarify the characteristics of motor neuron excitability by
examining the soleus H-reflex in the ready position adopted immediately before making a
return during badminton games. [Subjects] Sixteen individuals with (badminton group) and
16 without (control group) experience of playing badminton were studied. [Methods] Each
subject was instructed to take up various stances for returning a shuttlecock to measure
the H- and M-waves in the soleus. [Results] The H-wave was significantly decreased when
gripping a racket was held in the dominant hand than compared to just standing in the
badminton group. In contrast, in the control group, no significant differences were
observed between when standing and the other stances. [Conclusion] Based on these results,
the excitability of spinal motor neurons may have been reduced (H-wave suppression) by
badminton training to increase the instantaneous force (power training).
Collapse
Affiliation(s)
- Yujiro Masu
- Department of Physical Therapy, Health Science University, Japan
| | - Ken Muramatsu
- Department of Physical Therapy, Health Science University, Japan
| |
Collapse
|
14
|
Watanabe S, Oya Y, Iwata J, Someya F. Influences of Changes in the Level of Support and Walking Speed on the H Reflex of the Soleus Muscle and Circulatory Dynamics on Body Weight-supported Treadmill Training: Investigation in Healthy Adults. J Phys Ther Sci 2014; 26:1345-50. [PMID: 25276013 PMCID: PMC4175234 DOI: 10.1589/jpts.26.1345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/27/2014] [Indexed: 12/02/2022] Open
Abstract
[Purpose] To investigate the therapeutic usefulness of treadmill walking using a body
weight support device (BWS), changes in circulatory dynamics and muscle activities with
various levels of support were investigated. [Subjects and Methods] The subjects were
divided into 3 groups: 20% BWS, 40% BWS, and full body weight (FBW). The subjects walked
at maximum and normal speeds. Under each condition, H and M waves and skin temperature
before and after walking and changes in the heart rate during walking were measured.
[Results] The heart rate continued to increase after 3 minutes of FBW at the maximum
walking speed, but a steady state was reached after 3 minutes under the other walking
conditions. Regarding skin temperature, no significant difference from that at rest was
noted 30 minutes after walking at the normal speed, but it was significantly higher than
that at rest at 30 minutes after walking at the maximum speed. The H/M ratio was
significantly higher after walking at the maximum walking speed in the FBW and 20% BWS
groups compared with the 40% BWS groups. [Conclusion] Treatment with 40% BWS at the
maximum walking speed was safe for the circulatory system and may be effective in
elevating the skin temperature for a prolonged period compared with the effects of the
other walking conditions at normal speed.
Collapse
Affiliation(s)
- Shinichi Watanabe
- Graduate School of Medical Science, Division of Health Sciences, Graduate Course of Rehabilitation Science, Kanazawa University, Japan ; Department of Rehabilitation Medicine, Nagoya Medical Center, Japan
| | - Yosuke Oya
- Department of Rehabilitation Medicine, Nanao Hospital, Japan
| | - Jun Iwata
- Department of Rehabilitation Medicine, Nanao Hospital, Japan
| | - Fujiko Someya
- Pharmaceutical and Health Sciences, School of Health Sciences, College of Medical, Kanazawa University, Japan
| |
Collapse
|
15
|
McHenry CL, Wu J, Shields RK. Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health. BMC Res Notes 2014; 7:334. [PMID: 24894666 PMCID: PMC4055276 DOI: 10.1186/1756-0500-7-334] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 05/21/2014] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI). FINDINGS The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9). CONCLUSIONS All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.
Collapse
Affiliation(s)
- Colleen L McHenry
- Department of Physical Therapy & Rehabilitation Science, Carver College of Medicine, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
| | - Jason Wu
- Department of Physical Therapy & Rehabilitation Science, Carver College of Medicine, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
| | - Richard K Shields
- Department of Physical Therapy & Rehabilitation Science, Carver College of Medicine, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA
| |
Collapse
|
16
|
Murray M, Hardee A, Goldberg RL, Lewek MD. Loading and knee flexion after stroke: Less does not equal more. J Electromyogr Kinesiol 2014; 24:172-7. [DOI: 10.1016/j.jelekin.2013.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/22/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022] Open
|
17
|
Sayenko DG, Angeli C, Harkema SJ, Edgerton VR, Gerasimenko YP. Neuromodulation of evoked muscle potentials induced by epidural spinal-cord stimulation in paralyzed individuals. J Neurophysiol 2013; 111:1088-99. [PMID: 24335213 DOI: 10.1152/jn.00489.2013] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Epidural stimulation (ES) of the lumbosacral spinal cord has been used to facilitate standing and voluntary movement after clinically motor-complete spinal-cord injury. It seems of importance to examine how the epidurally evoked potentials are modulated in the spinal circuitry and projected to various motor pools. We hypothesized that chronically implanted electrode arrays over the lumbosacral spinal cord can be used to assess functionally spinal circuitry linked to specific motor pools. The purpose of this study was to investigate the functional and topographic organization of compound evoked potentials induced by the stimulation. Three individuals with complete motor paralysis of the lower limbs participated in the study. The evoked potentials to epidural spinal stimulation were investigated after surgery in a supine position and in one participant, during both supine and standing, with body weight load of 60%. The stimulation was delivered with intensity from 0.5 to 10 V at a frequency of 2 Hz. Recruitment curves of evoked potentials in knee and ankle muscles were collected at three localized and two wide-field stimulation configurations. Epidural electrical stimulation of rostral and caudal areas of lumbar spinal cord resulted in a selective topographical recruitment of proximal and distal leg muscles, as revealed by both magnitude and thresholds of the evoked potentials. ES activated both afferent and efferent pathways. The components of neural pathways that can mediate motor-evoked potentials were highly dependent on the stimulation parameters and sensory conditions, suggesting a weight-bearing-induced reorganization of the spinal circuitries.
Collapse
Affiliation(s)
- Dimitry G Sayenko
- Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | | | | | | | | |
Collapse
|
18
|
Masani K, Sayenko DG, Vette AH. What triggers the continuous muscle activity during upright standing? Gait Posture 2013; 37:72-7. [PMID: 22824676 DOI: 10.1016/j.gaitpost.2012.06.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/28/2012] [Accepted: 06/12/2012] [Indexed: 02/02/2023]
Abstract
The ankle extensors play a dominant role in controlling the equilibrium during bipedal quiet standing. Their primary role is to resist the gravity toppling torque that pulls the body forward. The purpose of this study was to investigate whether the continuous muscle activity of the anti-gravity muscles during standing is triggered by the joint torque requirement for opposing the gravity toppling torque, rather than by the vertical load on the lower limbs. Healthy adults subjects stood on a force plate. The ankle torque, ankle angle, and electromyograms from the right lower leg muscles were measured. A ground-fixed support device was used to support the subject at his/her knees, without changing the posture from the free standing one. During the supported condition, which eliminates the ankle torque requirement while maintaining both the vertical load on the lower limbs and the natural upright standing posture, the plantarflexor activity was attenuated to the resting level. Also, this attenuated plantarflexor activity was found only in one side when the ipsilateral leg was supported. Our results suggest that the vertical load on the lower limb is not determinant for inducing the continuous muscle activity in the anti-gravity muscles, but that it depends on the required joint torque to oppose the gravity toppling torque.
Collapse
Affiliation(s)
- Kei Masani
- Lyndhurst Centre, Toronto Rehabilitation Institute, Toronto, ON M4G 3V9, Canada.
| | | | | |
Collapse
|
19
|
Tseng SC, Shields RK. Limb compressive load does not inhibit post activation depression of soleus H-reflex in indiviudals with chronic spinal cord injury. Clin Neurophysiol 2012; 124:982-90. [PMID: 23168355 DOI: 10.1016/j.clinph.2012.10.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/02/2012] [Accepted: 10/27/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVE We investigated the effect of various doses of limb compressive load on soleus H-reflex amplitude and post activation depression in individuals with/without chronic SCI. We hypothesized that SCI reorganization changes the typical reflex response to an external load. METHODS Ten healthy adults and 10 individuals with SCI received three doses of compressive load to the top of their knee (10%, 25%, and 50% of the body weight, BW). Soleus H-reflexes were measured before (baseline) and during the loading phase. RESULTS With persistent background muscle activity across all testing sessions, segment compressive load significantly decreased post activation depression in the control group, but did not change the post activation ratio in the SCI group. Normalized H2 amplitude significantly increased according to load (50%> 25%> 10%) in the control group whereas was minimally modulated to load in those with SCI. CONCLUSIONS Segment compressive load inhibits post activation depression in humans without SCI, but minimally modulates the reflex circuitry in people with chronic SCI. These findings suggest that spinal cord reorganization mitigates the typical response to load in people with chronic SCI. SIGNIFICANCE Early limb load training may impact the reorganization of the spinal cord in humans with acute SCI.
Collapse
|
20
|
Modulating effects of bodyweight unloading on the lower limb nociceptive withdrawal reflex during symmetrical stance. Clin Neurophysiol 2012; 123:1035-43. [DOI: 10.1016/j.clinph.2011.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 08/31/2011] [Accepted: 09/05/2011] [Indexed: 11/22/2022]
|
21
|
Limb segment load inhibits post activation depression of soleus H-reflex in humans. Clin Neurophysiol 2012; 123:1836-45. [PMID: 22418592 DOI: 10.1016/j.clinph.2012.02.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/06/2012] [Accepted: 02/10/2012] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We investigated the effect of various doses of limb segment load on soleus H-reflex amplitude and post activation depression in healthy individuals. We also explored the influence of limb segment load on spinal circuitry in one individual with chronic SCI. METHODS Twenty-eight healthy adults and one SCI subject received compressive loads applied to the top of their knee at varied doses of load (10%, 25%, and 50% of the body weight). Soleus H-reflexes were measured before (baseline) and during the loading phase. RESULTS There were no significant differences in H-reflex amplitudes during the 50% BW load-on phase as compared to either baseline session or the load-off phase. However, the post activation depression was decreased over 9% (p<0.05) during the load-on phase compared to the load-off phase and scaled according to load (50%>25%>10%). The post activation depression ratio also appears less responsive to varying loads after chronic SCI. CONCLUSIONS Limb segment load decreases post-activation depression in humans. These findings suggest that the mechanism associated with post activation depression is modulated by limb segment load, and may be influenced by spinal reorganization after SCI. SIGNIFICANCE Future studies will determine if various levels of spasticity modulate the response of limb segment load on post activation depression in those with acute and chronic SCI.
Collapse
|
22
|
Different modulation pattern of spinal stretch reflex excitability in highly trained endurance runners. Eur J Appl Physiol 2012; 112:3641-8. [PMID: 22350360 DOI: 10.1007/s00421-012-2351-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 02/03/2012] [Indexed: 10/28/2022]
Abstract
This study was undertaken to elucidate the impact of long-term physical training on the modulation of stretch reflex excitability. To this end, electromyographic activities of the soleus muscle in response to quick toe-up rotation were compared between highly trained endurance runners (n = 8) and non-trained control subjects (n = 9). We specifically focused on the stretch reflex modulation under different voluntary activation levels, from rest to pre-activated conditions (5, 10, 20, and 30% of the maximal). While the two groups showed similar modulation patterns of the stretch reflex responses, the extent of reflex modulation in accordance with the muscle pre-activation level was larger in the trained group. The present results therefore suggest a different modulation pattern of the stretch reflex responses with changing activation level between individuals with different physical background, and the enhancement of the responses in the trained individuals may particularly be advantageous in exerting high level muscle contraction.
Collapse
|
23
|
Karaca S, Tan M, Tan U. Lateralized α-motoneuron excitabilities during lying and standing of healthy individuals in relation to parkinsonian rigidity. Neurol Res 2011; 33:976-82. [PMID: 22081001 DOI: 10.1179/1743132811y.0000000024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES To elucidate mechanisms of Parkinsonian rigidity by assessing excitability of alpha-motoneurons innervating right and left soleus muscles in healthy controls and Parkinson's disease (PD) patients with rigidities in the right, left and both legs. METHODS One group of 45 controls was recruited and 60 PD patients in three groups: rigidities, predominantly in the right, left and both legs. H-reflex (H) and muscle response (M) were recorded from right and left soleus muscles during stimulations of the posterior tibial nerve at the popliteal fossa while lying and standing. The H/M ratio was taken as an index for motoneuron excitability. RESULTS Mean H/M ratios were significantly different on the right and left sides, modified by postural changes in controls and PD patients. Analysis of variance showed that in healthy subjects the H/M ratio was: standing>lying (right), lying>standing (left). In right leg rigidity patients, the H/M ratio was greatest during standing, and smallest during lying. In left leg rigidity patients, the H/M ratios on the right and left sides were equally independent of posture. In controls, left H/M>right while lying, <right while standing. In right leg rigidity patients, right H/M>left, but <right in left leg rigidity patients, independent of posture. There was no side difference in patients with rigidity in both legs. CONCLUSIONS (i) motoneuron excitability may show side and postural differences in healthy individuals and PD patients; (ii) posture may be associated with lateralized motoneuron excitability in these subjects; and (iii) Parkinsonian rigidity may have spinal motor origins.
Collapse
Affiliation(s)
- Sibel Karaca
- Department of Neurology, Adana Teaching and Research Center, Faculty of Medicine, Baskent University, Adana, Turkey
| | | | | |
Collapse
|
24
|
Hwang S, Jeon HS, Kwon OY, Yi CH. The effects of body weight on the soleus H-reflex modulation during standing. J Electromyogr Kinesiol 2011; 21:445-9. [PMID: 21144768 DOI: 10.1016/j.jelekin.2010.11.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 10/01/2010] [Accepted: 11/05/2010] [Indexed: 11/25/2022] Open
|
25
|
Keller M, Pfusterschmied J, Buchecker M, Müller E, Taube W. Improved postural control after slackline training is accompanied by reduced H-reflexes. Scand J Med Sci Sports 2011; 22:471-7. [PMID: 21385217 DOI: 10.1111/j.1600-0838.2010.01268.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
"Slacklining" represents a modern sports activity where people have to keep balance on a tightened ribbon. The first trials on the slackline result in uncontrollable lateral swing of the supporting leg. Training decreases those oscillations and therefore improves postural control. However, the underlying neural mechanisms are not known. Therefore, the present study aimed to highlight spinal adaptations going along with slackline training. Twenty-four subjects were either assigned to a training or a control group and postural control was assessed before and after the 10 training sessions. Additionally, soleus Hoffmann (H)-reflexes were elicited to evaluate changes in the excitability of the spinal reflex circuitry. Trained subjects were able to maintain balance on the slackline for at least 20 s (P<0.001) and reduced platform movements on the balance board (P<0.05). The H-reflexes were significantly diminished (P<0.05) while no changes occurred in the background electromyography (bEMG). The control group showed no significant changes. From a functional point of view the reflex reduction may serve to suppress uncontrollable reflex mediated joint oscillations. As the bEMG remained unchanged, presynaptic rather than post-synaptic mechanisms are speculated to be responsible for the changes in the Ia-afferent transmission.
Collapse
Affiliation(s)
- M Keller
- Department of Medicine, Unit of Sports Science, University of Fribourg, Fribourg, Switzerland.
| | | | | | | | | |
Collapse
|
26
|
Enhanced excitability of the corticospinal pathway of the ankle extensor and flexor muscles during standing in humans. Exp Brain Res 2009; 197:207-13. [DOI: 10.1007/s00221-009-1874-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 05/20/2009] [Indexed: 10/20/2022]
|
27
|
Al Abdulwahab SS, Beatti AM. The effect of prone position and interferential therapy on lumbosacral radiculopathy. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/14038190600563296] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
28
|
Soleus H-reflex modulation during body weight support treadmill walking in spinal cord intact and injured subjects. Exp Brain Res 2008; 193:397-407. [PMID: 19011843 DOI: 10.1007/s00221-008-1636-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 10/24/2008] [Indexed: 10/21/2022]
Abstract
The soleus H-reflex modulation pattern was investigated in ten spinal cord intact subjects during treadmill walking at varying levels of body weight support (BWS), and nine spinal cord injured (SCI) subjects at a BWS level that promoted the best stepping pattern. The soleus H-reflex was elicited by tibial nerve stimulation with a single 1-ms pulse at an intensity that the M-waves ranged from 4 to 8% of the maximal M-wave (M(max)). During treadmill walking, the H-reflex was elicited every four steps, and stimuli were randomly dispersed across the gait cycle which was divided into 16 equal bins. EMGs were recorded with surface electrodes from major left and right hip, knee, and ankle muscles. M-waves and H-reflexes at each bin were normalized to the M(max) elicited at 60-100 ms after the test reflex stimulus. For every subject, the integrated EMG area of each muscle was established and plotted as a function of the step cycle phase. The H-reflex gain was determined as the slope of the relationship between H-reflex and soleus EMG amplitudes at 60 ms before H-reflex elicitation for each bin. In spinal cord intact subjects, the phase-dependent H-reflex modulation, reflex gain, and EMG modulation pattern were constant across all BWS (0, 25, and 50) levels, while tibialis anterior muscle activity increased with less body loading. In three out of nine SCI subjects, a phase-dependent H-reflex modulation pattern was evident during treadmill walking at BWS that ranged from 35 to 60%. In the remaining SCI subjects, the most striking difference was an absent H-reflex depression during the swing phase. The reflex gain was similar for both subject groups, but the y-intercept was increased in SCI subjects. We conclude that the mechanisms underlying cyclic H-reflex modulation during walking are preserved in some individuals after SCI.
Collapse
|
29
|
Ogawa T, Kim GH, Sekiguchi H, Akai M, Suzuki S, Nakazawa K. Enhanced stretch reflex excitability of the soleus muscle in experienced swimmers. Eur J Appl Physiol 2008; 105:199-205. [PMID: 18925414 DOI: 10.1007/s00421-008-0890-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2008] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to investigate effects of long-term participation to swimming on adaptations of spinal reflex excitability. To this end, mechanically induced stretch reflex (SR) and electrically induced Hoffmann (H-) reflex of the soleus muscle were investigated between swimmers with experience of more than 10 years and non-trained individuals while sitting at rest. The amplitude and the gain (stretch velocity vs. amplitude of the reflex response) of the SR were significantly greater in the swimming group than in the non-trained control group. Similarly, the responses of the H-reflex were also significantly greater in the swimming group than in the non-trained control group. Results of this study demonstrated that the spinal reflex excitability in experienced swimmers was far more enhanced than in non-trained individuals.
Collapse
Affiliation(s)
- Tetsuya Ogawa
- Graduate School of Human Sciences, Waseda University, 2-579-15, Mikajima, Tokorozawa, Saitama, Japan
| | | | | | | | | | | |
Collapse
|
30
|
Tokuno CD, Carpenter MG, Thorstensson A, Garland SJ, Cresswell AG. Control of the triceps surae during the postural sway of quiet standing. Acta Physiol (Oxf) 2007; 191:229-36. [PMID: 17635414 DOI: 10.1111/j.1748-1716.2007.01727.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The present study investigated how the triceps surae are controlled at the spinal level during the naturally occurring postural sway of quiet standing. METHODS Subjects stood on a force platform as electrical stimuli were applied to the posterior tibial nerve when the center of pressure (COP) was either 1.6 standard deviations anterior (COP(ant)) or posterior (COP(post)) to the mean baseline COP signal. Peak-to-peak amplitudes of the H-reflex and M-wave from the soleus (SOL) and medial gastrocnemius (MG) muscles were recorded to assess the efficacy of the Ia pathway. RESULTS A significant increase in the H(max) : M(max) ratio for both the SOL (12 +/- 6%) and MG (23 +/- 6%) was observed during the COP(ant) as compared to the COP(post) condition. The source of the modulation between COP conditions cannot be determined from this study. However, the observed changes in the synaptic efficacy of the Ia pathway are unlikely to be simply a result of an altered level of background electromyographic activity in the triceps surae. This was indicated by the lack of differences observed in the H(max) : M(max) ratio when subjects stood without postural sway (via the use of a tilt table) at two levels of background activity. CONCLUSIONS It is suggested that the phase-dependent modulation of the triceps surae H-reflexes during the postural sway of quiet standing functions to maintain upright stance and may explain the results from previous studies, which, until now, had not taken the influence of postural sway on the H-reflex into consideration.
Collapse
Affiliation(s)
- C D Tokuno
- Department of Neuroscience, Karolinska Institutet and The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | | | | | | | | |
Collapse
|
31
|
Influence of posture and stimulus parameters on post-activation depression of the soleus H-reflex in individuals with chronic spinal cord injury. Neurosci Lett 2006; 410:37-41. [PMID: 17046161 DOI: 10.1016/j.neulet.2006.09.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Revised: 09/22/2006] [Accepted: 09/24/2006] [Indexed: 10/24/2022]
Abstract
In non-disabled (ND) individuals, reflexes are modulated by influences related to physiologic state (e.g., posture, joint position, load) and activation history. Repeated activation of the H-reflex results in post-activation depression (PAD) of the response amplitude. The modulation associated with physiologic state and activation history is suppressed or abolished in individuals with spinal cord injury (SCI). While posture is known to affect H-reflex amplitude and PAD in non-disabled individuals, the effect of posture on PAD in SCI individuals is not known. Further, while the amount of PAD is also known to be influenced by the stimulus rate and by the amplitude of the evoked reflex, the interaction of posture with stimulus parameters has not been previously investigated in either group. We investigated differences in PAD of the soleus H-reflex between SCI subjects and ND subjects during sitting versus supported standing. Subjects were tested using paired conditioning-test stimulus pulses of 2.5s and 5s interpulse intervals (ISI) and with stimulus intensity adjusted to evoke reflex responses of 20% and 40% of the maximum motor response. We found standing posture to be associated with significantly less PAD in SCI subjects compared to ND subjects. In both groups, shorter ISIs and smaller reflex amplitudes were associated with greater PAD of the H-reflex. These results indicate that postural influences on post-activation modulation, while present, are impaired in individuals with chronic incomplete SCI.
Collapse
|
32
|
Kawashima N, Yano H, Ohta Y, Nakazawa K. Stretch reflex modulation during imposed static and dynamic hip movements in standing humans. Exp Brain Res 2006; 174:342-50. [PMID: 16767396 DOI: 10.1007/s00221-006-0470-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 03/21/2006] [Indexed: 10/24/2022]
Abstract
The purpose of this study was to investigate the effects of hip proprioceptors on soleus stretch reflex excitability in standing humans. A custom-made device to stretch the ankle extensors was mounted on the lower leg portion of a gait orthosis and was used to elicit stretch reflex responses while standing. Six subjects with motor complete spinal cord injury (SCI) and six spinal intact subjects were placed in the orthosis, and stretch reflex responses were elicited when static and/or dynamic hip joint angle changes were imposed. We found that static hip extension significantly enhanced the stretch reflex responses as compared to the neutral position and the hip flexion position only in the SCI group. The EMG magnitude induced by hip extension was 142 +/- 16.6% greater than that induced by the neutral position. When the leg was dynamically swung, the reflex responses also changed with the phase of the hip angle in the SCI group; in particular, the reflex amplitude was enhanced with hip extension and in the transition phase from flexion to extension. Although the magnitude of the changes was less than that in the SCI group, a similar type of modulation was found in the normal group. Given the fact that the persons with SCI had lost the neural connection between higher nervous center and the paralyzed lower limb muscles, the mechanism underlying the present results can be attributed to the peripheral afferent input due to the hip angle changes. We concluded that hip mediated afferent input has a significant influence on the excitability modulation of the soleus stretch reflex pathway. Such neural modulation may play a role in the mechanism responsible for the phase-dependent modulation of the stretch reflex while walking.
Collapse
Affiliation(s)
- Noritaka Kawashima
- Department of Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama, 359-8555, Japan.
| | | | | | | |
Collapse
|
33
|
Phadke CP, Wu SS, Thompson FJ, Behrman AL. Soleus H-reflex modulation in response to change in percentage of leg loading in standing after incomplete spinal cord injury. Neurosci Lett 2006; 403:6-10. [PMID: 16723187 DOI: 10.1016/j.neulet.2006.04.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2005] [Revised: 04/08/2006] [Accepted: 04/14/2006] [Indexed: 11/19/2022]
Abstract
Body weight support (BWS) is frequently used to retrain standing and walking in persons post spinal cord injury (SCI), but the effects of leg unloading using BWS on H-reflex excitability in this population are unknown. The purpose of the study was to assess the effect of two different loading conditions on soleus H-reflex while standing in persons with motor incomplete SCI (i-SCI) and non-injured persons. Eight persons with motor i-SCI (mean age 50.25 years) and five non-injured persons (mean age 48.6 years) participated in the study. Specific control of the loading conditions was achieved using a BWS system. To compare reflex modulation at 40% versus 0% BWS, soleus H-reflexes were evoked during standing and normalized to the maximum M wave amplitude. These studies revealed that (1) H-reflex excitability is significantly greater after SCI and is exhibited even during quiet standing; and (2) no significant modulation in reflex excitability was observed by change in loading conditions in either the non-injured or the i-SCI subjects. These findings suggest that non-injured persons and persons with i-SCI respond similarly to bilateral limb unloading during standing with no change in H-reflex amplitude. Our results suggest that BWS of up to 40% does not produce detectable changes in the excitability of the soleus H-reflex in persons with i-SCI.
Collapse
Affiliation(s)
- Chetan P Phadke
- Department of Physical Therapy, University of Florida, P.O. Box 100154, Gainesville, USA
| | | | | | | |
Collapse
|
34
|
Bove M, Trompetto C, Abbruzzese G, Schieppati M. The posture-related interaction between Ia-afferent and descending input on the spinal reflex excitability in humans. Neurosci Lett 2006; 397:301-6. [PMID: 16426752 DOI: 10.1016/j.neulet.2005.12.049] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Revised: 12/14/2005] [Accepted: 12/14/2005] [Indexed: 12/01/2022]
Abstract
The separate and combined depressive effects induced by vibration and standing on the soleus H-reflex have been studied by administering Achilles' tendon vibration in prone position and during stance. Without vibration, H-reflex amplitude was larger under prone than standing condition. Vibration reduced the reflex both in prone position and even more during stance. When vibration was superimposed to inclined stance (greater EMG background), the reflex was reduced of the same absolute amount as when it was superimposed to normal stance. When vibration was superimposed on stance with minimal or no background EMG, the reflex disappeared. These results confirm that both upright posture and vibration have a strong depressive effect on the H-reflex. They also show that muscle activity during stance is enough for overcoming the reflex depression. These findings provide information about the origin of the disfacilitatory effects on the monosynaptic reflex pathway, contribute to the understanding of the posture-related mechanisms responsible for the modulation of the spinal reflex excitability, and allow arguing in favour of a minor but adaptable role for the short latency stretch reflex in the control of quiet unperturbed stance.
Collapse
Affiliation(s)
- Marco Bove
- Department of Experimental Medicine, Section of Human Physiology, University of Genoa, Viale Benedetto XV, 3, Genoa I-16132, Italy.
| | | | | | | |
Collapse
|
35
|
Miyoshi T, Hotta K, Yamamoto SI, Nakazawa K, Akai M. Somatosensory graviception inhibits soleus H-reflex gain in humans during walking. Exp Brain Res 2005; 169:135-8. [PMID: 16365752 DOI: 10.1007/s00221-005-0289-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Accepted: 11/01/2005] [Indexed: 11/26/2022]
Abstract
To investigate the effects of gravity-related somatosensory information on spinal human reflexes, the soleus H-reflex was recorded in ten healthy subjects walking on a treadmill at 2.0 km/h on land and in water. The modulation pattern of the soleus H-reflex was determined in ten different phases of the step cycle. While the subjects were walking in water, the background electromyographic activity (BGA) of the soleus was lower than that on land; on the other hand, the soleus H-reflex amplitude while the subjects were walking in water showed no significant differences throughout the step cycle compared with that while the subjects were on land; the phase-dependent soleus H-reflex modulation pattern was well preserved while walking in water. There was a linear relationship between the BGA and the H-reflex amplitude in each condition; however, the soleus H-reflex gain while walking in water was significantly higher than that on land. These findings suggest that the somatosensory graviception can markedly reduce the spinal reflex excitability. Our findings are discussed in relation to human gait; therefore, further studies are needed to clarify the effect of somatosensory graviception on human neural mechanisms.
Collapse
Affiliation(s)
- Tasuku Miyoshi
- Faculty of Systems Engineering, Shibaura Institute of Technology, 307 Fukasaku, 3308570 Saitama-City, Japan.
| | | | | | | | | |
Collapse
|