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Burke D. Crosstalk opposing view: Independent fusimotor control of muscle spindles in humans: there is little to gain. J Physiol 2021; 599:2505-2508. [PMID: 33749872 DOI: 10.1113/jp281337] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- David Burke
- Department of Neurology, Royal Prince Alfred Hospital and The University of Sydney, New South Wales 2006, Australia
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2
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Modulation of tendon tap reflex activation of soleus motor neurons with reduced stability tandem stance. Hum Mov Sci 2019; 64:274-282. [DOI: 10.1016/j.humov.2019.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 02/06/2019] [Accepted: 02/19/2019] [Indexed: 11/22/2022]
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Magrini MA, Thiele RM, Colquhoun RJ, Barrera-Curiel A, Blackstock TS, DeFreitas JM. The reactive leg drop: a simple and novel sensory-motor assessment to predict fall risk in older individuals. J Neurophysiol 2018; 119:1556-1561. [PMID: 29357449 DOI: 10.1152/jn.00713.2017] [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
There is need for a functional ability test that appropriately assesses the rapid integration of the sensory and motor systems required for older adults to recover from a slip. The purpose of this study was to assess the efficacy and reliability of a novel test, the reactive leg drop, for assessing sensory-motor function in older adults. Fourteen young (YW; mean age = 20 yr) and 11 older women (OW; mean age = 76 yr) participated in this study. For each drop, the leg was passively moved to full extension and then released. The subjects had to recognize their leg was free-falling and reactively kick up as quickly as possible during varying sensory conditions. To assess the leg drop's reliance on proprioception, other proprioceptive tests (e.g., patellar tendon reflexes and balance) were separately performed. Leg drops performed with the eyes closed ( P = 0.011) and with a blocked view of the leg ( P = 0.033) showed significant differences in drop angle between YW and OW. Significant relationships between leg drop conditions and balance were observed in OW that were not present within YW. When collapsed across groups, reflex latency was correlated with drop angle when the eyes were closed. The reactive leg drop was age sensitive, reliable, and likely reliant on proprioception, as shown by relationships to other sensory-motor assessments, such as balance and the patellar reflex. Although more research is needed, we propose that the reactive leg drop is an effective tool to assess sensory-motor integration in a manner that may mimic fall recovery. NEW & NOTEWORTHY The reactive leg drop was age sensitive and was significantly related to other sensory-motor assessments. The ability to accurately assess sensory-motor integration may aid clinicians, practitioners, and researchers in developing new interventions. The reactive leg drop presented in the current study is a potentially effective tool to assess sensory and motor integration in a manner that may mimic fall recovery.
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Affiliation(s)
- Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Ryan M Thiele
- Department of Food, Nutrition, Dietetics and Health, Kansas State University , Manhattan, Kansas
| | - Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | | | - Taryn S Blackstock
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
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4
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Klarner T, Barss TS, Sun Y, Kaupp C, Loadman PM, Zehr EP. Long-Term Plasticity in Reflex Excitability Induced by Five Weeks of Arm and Leg Cycling Training after Stroke. Brain Sci 2016; 6:brainsci6040054. [PMID: 27827888 PMCID: PMC5187568 DOI: 10.3390/brainsci6040054] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/22/2016] [Accepted: 10/28/2016] [Indexed: 12/21/2022] Open
Abstract
Neural connections remain partially viable after stroke, and access to these residual connections provides a substrate for training-induced plasticity. The objective of this project was to test if reflex excitability could be modified with arm and leg (A & L) cycling training. Nineteen individuals with chronic stroke (more than six months postlesion) performed 30 min of A & L cycling training three times a week for five weeks. Changes in reflex excitability were inferred from modulation of cutaneous and stretch reflexes. A multiple baseline (three pretests) within-subject control design was used. Plasticity in reflex excitability was determined as an increase in the conditioning effect of arm cycling on soleus stretch reflex amplitude on the more affected side, by the index of modulation, and by the modulation ratio between sides for cutaneous reflexes. In general, A & L cycling training induces plasticity and modifies reflex excitability after stroke.
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Affiliation(s)
- Taryn Klarner
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada.
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada.
| | - Trevor S Barss
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada.
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada.
| | - Yao Sun
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada.
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada.
| | - Chelsea Kaupp
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada.
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada.
| | - Pamela M Loadman
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
| | - E Paul Zehr
- Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC V8W 3P1, Canada.
- Human Discovery Science, International Collaboration on Repair Discoveries (ICORD), Vancouver, BC V5Z 1M9, Canada.
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2, Canada.
- Division of Medical Sciences, University of Victoria, BC V8P 5C2, Canada.
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Pope ZK, DeFreitas JM. The effects of acute and prolonged muscle vibration on the function of the muscle spindle’s reflex arc. Somatosens Mot Res 2015; 32:254-61. [DOI: 10.3109/08990220.2015.1091770] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Zachary K. Pope
- Applied Musculoskeletal and Human Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
| | - Jason M. DeFreitas
- Applied Musculoskeletal and Human Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
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6
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Pope ZK, DeFreitas JM. The effects of body position and muscle activation on patellar tendon reflex properties. Physiol Meas 2015; 36:1429-38. [DOI: 10.1088/0967-3334/36/7/1429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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The representation of egocentric space in the posterior parietal cortex. Behav Brain Sci 2013; 15 Spec No 4:691-700. [PMID: 23842408 DOI: 10.1017/s0140525x00072605] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The posterior parietal cortex (PPC) is the most likely site where egocentric spatial relationships are represented in the brain. PPC cells receive visual, auditory, somaesthetic, and vestibular sensory inputs; oculomotor, head, limb, and body motor signals; and strong motivational projections from the limbic system. Their discharge increases not only when an animal moves towards a sensory target, but also when it directs its attention to it. PPC lesions have the opposite effect: sensory inattention and neglect. The PPC does not seem to contain a "map" of the location of objects in space but a distributed neural network for transforming one set of sensory vectors into other sensory reference frames or into various motor coordinate systems. Which set of transformation rules is used probably depends on attention, which selectively enhances the synapses needed for making a particular sensory comparison or aiming a particular movement.
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8
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Rhythmic arm cycling differentially modulates stretch and H-reflex amplitudes in soleus muscle. Exp Brain Res 2011; 214:529-37. [PMID: 21901451 DOI: 10.1007/s00221-011-2851-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 08/23/2011] [Indexed: 10/17/2022]
Abstract
During rhythmic arm cycling, soleus H-reflex amplitudes are reduced by modulation of group Ia presynaptic inhibition. This suppression of reflex amplitude is graded to the frequency of arm cycling with a threshold of 0.8 Hz. Despite the data on modulation of the soleus H-reflex amplitude induced by rhythmic arm cycling, comparatively little is known about the modulation of stretch reflexes due to remote limb movement. Therefore, the present study was intended to explore the effect of arm cycling on stretch and H-reflex amplitudes in the soleus muscle. In so doing, additional information on the mechanism of action during rhythmic arm cycling would be revealed. Although both reflexes share the same afferent pathway, we hypothesized that stretch reflex amplitudes would be less suppressed by arm cycling because they are less inhibited by presynaptic inhibition. Failure to reject this hypothesis would add additional strength to the argument that Ia presynaptic inhibition is the mechanism modulating soleus H-reflex amplitude during rhythmic arm cycling. Participants were seated in a customized chair with feet strapped to footplates. Three motor tasks were performed: static control trials and arm cycling at 1 and 2 Hz. Soleus H-reflexes were evoked using single 1 ms pulses of electrical stimulation delivered to the tibial nerve at the popliteal fossa. A constant M-wave and ~6% MVC activation of soleus were maintained across conditions. Stretch reflexes were evoked using a single sinusoidal pulse at 100 Hz given by a vibratory shaker placed over the triceps surae tendon and controlled by a custom-written LabView program. Results demonstrated that rhythmic arm cycling that was effective for conditioning soleus H-reflexes did not show a suppressive effect on the amplitude of the soleus stretch reflex. We suggest this indicates that stretch reflexes are less sensitive to conditioning by rhythmic arm movement, as compared to H-reflexes, due to the relative insensitivity to Ia presynaptic inhibition.
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10
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Abstract
Abstract
This target article draws together two groups of experimental studies on the control of human movement through peripheral feedback and centrally generated signals of motor commands. First, during natural movement, feedback from muscle, joint, and cutaneous afferents changes; in human subjects these changes have reflex and kinesthetic consequences. Recent psychophysical and microneurographic evidence suggests that joint and even cutaneous afferents may have a proprioceptive role. Second, the role of centrally generated motor commands in the control of normal movements and movements following acute and chronic deafferentation is reviewed. There is increasing evidence that subjects can perceive their motor commands under various conditions, but that this is inadequate for normal movement; deficits in motor performance arise when the reliance on proprioceptive feedback is abolished either experimentally or because of pathology. During natural movement, the CNS appears to have access to functionally useful input from a range of peripheral receptors as well as from internally generated command signals. The unanswered questions that remain suggest a number of avenues for further research.
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11
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Equilibrium-point hypothesis, minimum effort control strategy and the triphasic muscle activation pattern. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00073209] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Successive approximation in targeted movement: An alternative hypothesis. Behav Brain Sci 2011. [DOI: 10.1017/s0140525x00072848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
AbstractEngineers use neural networks to control systems too complex for conventional engineering solutions. To examine the behavior of individual hidden units would defeat the purpose of this approach because it would be largely uninterpretable. Yet neurophysiologists spend their careers doing just that! Hidden units contain bits and scraps of signals that yield only arcane hints about network function and no information about how its individual units process signals. Most literature on single-unit recordings attests to this grim fact. On the other hand, knowing a system's function and describing it with elegant mathematics tell one very little about what to expect of interneuronal behavior. Examples of simple networks based on neurophysiology are taken from the oculomotor literature to suggest how single-unit interpretability might decrease with increasing task complexity. It is argued that trying to explain how any real neural network works on a cell-by-cell, reductionist basis is futile and we may have to be content with trying to understand the brain at higher levels of organization.
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15
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Does the nervous system use equilibrium-point control to guide single and multiple joint movements? Behav Brain Sci 2011; 15:603-13. [PMID: 23302290 DOI: 10.1017/s0140525x00072538] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Nardone A, Schieppati M. Inhibitory effect of the Jendrassik maneuver on the stretch reflex. Neuroscience 2008; 156:607-17. [DOI: 10.1016/j.neuroscience.2008.07.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/18/2008] [Accepted: 07/21/2008] [Indexed: 12/29/2022]
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Chapter 10 Reflex responses, silent period and long latency reflexes. HANDBOOK OF CLINICAL NEUROPHYSIOLOGY 2006. [DOI: 10.1016/s1567-4231(09)70071-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Abstract
The deep tendon reflexes (and the abdominal reflexes) are important physical signs which have a special place in neurological diagnosis, particularly in early disease when they alone may be abnormal. They act as "hard" signs in situations where clinical assessment is complicated by patient anxiety, and become more useful as clinical experience develops.
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Affiliation(s)
- J P R Dick
- Greater Manchester Neuroscience Centre, Hope Hospital, Salford M8 6HD, UK.
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20
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Robichaud JA, Brunt D, Tennant LK. Spinal cord modulation associated with isometric contractions. Brain Res 2002; 950:64-73. [PMID: 12231229 DOI: 10.1016/s0006-8993(02)02986-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The dual-strategy hypothesis explains single-joint voluntary movement by dividing movements into two different strategies and suggesting that different excitation pulses modulate these movements. The existence of this excitation pulse was evaluated by quantifying magnitude and timing changes in the H-reflex (changes in spinal excitability) prior to a voluntary contraction. These changes in spinal excitability were assessed during a ballistic plantar flexion isometric contraction, where both the target size and force level was manipulated. METHODS AND MATERIALS Subjects were seated in a modified chair with a force transducer placed under the metatarsal heads to measure ankle force output. Following a visual stimulus subjects were trained to produce a plantar flexion force of 25% and 50% of a maximum voluntary contraction, within target sizes of 5% and 15% of the selected force level. Soleus motor neuron reflex excitability was analyzed by measuring changes in the H/M ratio. The H-reflex was randomly elicited by tibial nerve stimulations at 15, 30, 45, 60, 75 and 90 ms prior to the recorded average soleus premotor time for each of the force and target size conditions. RESULTS A two-way repeated-measures analysis of variance indicated a significant effect among target sizes for the time of change in spinal excitability, slope of facilitation (rate of rise of spinal excitability), and peak facilitation. A significant difference was also established between force levels for the slope and peak facilitation, but there was no difference with time of facilitation. CONCLUSIONS These results indicate that changes in both target size and force level can influence slope and peak of facilitation. However, only target size appears to affect the time of facilitation. Results clearly support the existence of an excitation pulse that is regulated by the type of movement.
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Affiliation(s)
- Julie A Robichaud
- School of Kinesiology, Motor Control Laboratory, University of Illinois at Chicago, 901 W. Roosevelt Road, Chicago, IL 60608-1516, USA.
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Sugawara K, Kasai T. Facilitation of motor evoked potentials and H-reflexes of flexor carpi radialis muscle induced by voluntary teeth clenching. Hum Mov Sci 2002; 21:203-12. [PMID: 12167299 DOI: 10.1016/s0167-9457(02)00099-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In order to examine the effects of remote facilitation on cortical and spinal sites, we recorded motor evoked potentials (MEPs) and H-reflexes from the flexor carpi radialis muscle of 13 healthy subjects. The H-reflex was used to assess excitability changes at the spinal level, while the MEP following transcranial magnetic stimulation was used to study excitability changes at the cortical level. We induced remote facilitation by means of voluntary teeth clenching (VTC), the so-called Jendrassik maneuver, because this procedure is known to be effective and reliable. Although the facilitation induced by VTC was observed in both evoked potentials (i.e., H-reflex and MEP), which is consistent with previous reports, MEP onset latencies were shortened by VTC in proportion to an increased MEP amplitude, whereas the latencies of the H-reflex were not. Furthermore, statistically significant relationships between MEP latencies and amplitudes were observed in all subjects, whereas no such relationships were observed for the H-reflex. On the basis of these results, two neural pathways are presumed: one involving a release of pre-synaptic inhibition at the spinal level and the other involving an unmasking of lateral excitatory projections at the cortical level.
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Affiliation(s)
- Kenichi Sugawara
- Department of Restorative Science, Faculty of Medical Professions, Kawasaki University of Medical Welfare, Kawasaki City, Japan
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Takahashi T, Ueno T, Taniguchi H, Ohyama T, Nakamura Y. Modulation of H reflex of pretibial and soleus muscles during mastication in humans. Muscle Nerve 2001; 24:1142-8. [PMID: 11494266 DOI: 10.1002/mus.1125] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A previous study in our laboratory demonstrated that the soleus H reflex was facilitated during mastication in humans. In the present study, we investigated whether there was any modulation of the magnitude of the pretibial H reflex during mastication in five healthy adult volunteers. The pretibial H reflex was significantly facilitated during mastication, and there was no significant difference in the facilitation between jaw-closing and jaw-opening phases; that is, the gain of the H reflex was modulated tonically but not in a phase-dependent manner during mastication. Furthermore, in the same subjects, we confirmed that the soleus H reflex was facilitated during mastication. Based on our findings, we conclude that the H reflexes in both the pretibial and soleus muscles undergo a nonreciprocal facilitation during mastication. It is suggested that mastication contributes to stabilization of postural stance in humans.
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Affiliation(s)
- T Takahashi
- Department of Maxillofacial Reconstruction and Function, Division of Maxillofacial/Neck Reconstruction, Graduate School, Tokyo Medical and Dental University, 5-45 Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan.
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Uysal H, Mogyoros I, Burke D. Reproducibility of tendon jerk reflexes during a voluntary contraction. Clin Neurophysiol 1999; 110:1481-7. [PMID: 10454287 DOI: 10.1016/s1388-2457(99)00082-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES The present study explored whether testing tendon jerks during voluntary contraction of the test muscle would improve reproducibility by effectively 'clamping' the excitability of the motoneurone pool at firing threshold. METHODS Tendon jerk reflexes of soleus, tibialis anterior and vastus lateralis and the soleus H reflex were recorded in 12 healthy subjects at rest and during voluntary contractions of 10-20% of maximum. Recordings were repeated 8-10 times in 5 subjects, in whom reflex symmetry was also determined. RESULTS Not all tendon jerk reflexes could be recorded at rest, and the variability of latency and amplitude was high. All reflexes could be recorded in each subject during contractions. The latency of tendon jerk reflexes decreased by approximately 2 ms during contractions, but H-reflex latency decreased by only 0.2-0.3 ms. For the tendon jerks, an asymmetry of >3.0 ms at rest and >2.5 ms contracting would be outside 3 SD of the normal mean. In repeat studies, the coefficient of variation of reflex latency was <4% for the tendon jerk. CONCLUSIONS A voluntary contraction could potentiate the tendon jerk by a number of mechanisms, but the most important is probably enhancement of the excitability of the motoneurone pool. The present techniques should increase the value of tendon reflex testing when assessing possible peripheral nerve, plexus and root disturbances.
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Affiliation(s)
- H Uysal
- Department of Neurology, Prince of Wales Hospital, Prince of Wales Medical Research Institute, and University of New South Wales, Sydney, Australia
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Abstract
The sacral cord conduction time of the soleus H-reflex was investigated in 30 normal adult subjects using three different methods. (1) The posterior tibial nerve was stimulated at the popliteal fossa by graded electric shocks, and the recordings were made from different lumbar epidural intervertebral levels. The afferent action potentials from the dorsal roots and the reflexively evoked efferent action potentials from the ventral roots were recorded. The time interval between the negative peaks of the ventral and dorsal root potentials was used to calculate the approximate sacral cord reflex delay time, which was found to be 1.3 ms. on average. (2) The sacral cord reflex delay time was found to be about 2.0 ms using the conduction time of the afferent, that of the efferent limbs and total reflex time of the soleus H-response. (3) By stimulating the lumbosacral roots at the epidural levels and using the difference between the soleus H and M response latencies, the sacral cord reflex delay was determined to be approximately 2.4 ms. These findings indicated that the soleus H-reflex is exclusively monosynaptic. It is proposed that in humans the synaptic transmission at the sacral cord is approximately 0.4 ms.
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Affiliation(s)
- C Ertekin
- Department of Neurology, Medical School Hospital, Ege University Bornova, Izmir, Turkey
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Rau H, Brody S, Brunia CH, Damen EP, Elbert T. Activation of carotid baroreceptors inhibits spinal reflexes in man. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1993; 89:328-34. [PMID: 7691572 DOI: 10.1016/0168-5597(93)90072-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The present study was designed to investigate the effect of baroreceptors on a spinal reflex. The Achilles tendon reflex (T reflex), a monosynaptic spinal reflex, was chosen as an indicator of descending influences of central activation. The baroreceptors are stretch receptors which respond to extensions of the arterial wall. Carotid sinus baroreceptors can be manipulated non-invasively by means of a cuff around the neck. In this study, the phase-related external suction (PRES) neck cuff technique was used. PRES applies short changes in cuff pressure as a function of heart cycle phase, controlling for non-specific effects found in other baroreceptor manipulation methods. The T reflex was reduced when elicited during the highest levels of baroreceptor activation. Reflex amplitude was largest when elicited during the lowest levels of baroreceptor activation. These results are consistent with previous findings that baroreceptor activation reduces CNS excitability.
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Affiliation(s)
- H Rau
- Medical Psychology, University of Tübingen, Germany
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Abstract
The influence of vibration on the H-reflex and on the tendon reflex amplitudes was compared and the efficacy of both methods for the assessment of the presynaptic inhibition was studied. One hundred and twenty patients with post-stroke spastic hemiparesis were investigated. Muscle tone, muscle force and tendon reflexes were assessed. The H-reflex and the Achilles tendon reflex (TA) were recorded under identical experimental conditions. Vibration at a frequency of 100 Hz and an amplitude of 2 mm was applied to the TA. Just after vibration the maximal amplitudes of both reflexes were measured. The ratios of reflex amplitudes after vibration to normal maximal reflex amplitudes (Hvibr/Hmax and TAvibr/TAmax) were evaluated. In all patients with hemiparesis the healthy side was used as a control. Our results revealed significantly increased amplitude ratios on the spastic side. Hence it is concluded that presynaptic inhibition is decreased in spasticity. The amplitude ratios on the healthy and the spastic side were consistent. There was good positive correlation between Hvibr/Hmax and TAvibr/TAmax ratios, suggesting that they provide similar and reliable estimates of presynaptic inhibition.
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Affiliation(s)
- I Milanov
- Institute of Neurology, Psychiatry and Neurosurgery, Bulgarian Medical Academy, Sofia
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Abbruzzese M, Reni L, Favale E. Interindividual variability of central delay changes in the soleus H reflex pathway. Muscle Nerve 1992; 15:21-6. [PMID: 1310157 DOI: 10.1002/mus.880150105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Central delay (CD) changes in the soleus H reflex pathway, as demonstrated by variations in the time interval between afferent (P1) and efferent (P2) neurographic volleys underlying the reflex response, were assessed in a group of normal subjects, both during the steady state and after homosynaptic spatial summation of afferent impulses. The maximal range of CD changes, regardless of whether "spontaneous" or provoked, showed significant interindividual differences whose size was positively related to the Hmax/Mmax ratio, provided that the extension of the subliminal fringe was suitably normalized. Comparatively similar variations in amplitude of the reflex motoneuronal discharge under different experimental conditions can be associated with different CD changes. Indeed, "spontaneous" CD fluctuations occurring during the steady state were consistently greater than CD reductions provoked by spatial summation, the gap size being negatively related to the Hmax/Mmax ratio.
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Affiliation(s)
- M Abbruzzese
- Department of Neurology, University of Genoa, Italy
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Thilmann AF, Fellows SJ, Garms E. Pathological stretch reflexes on the "good" side of hemiparetic patients. J Neurol Neurosurg Psychiatry 1990; 53:208-14. [PMID: 2324753 PMCID: PMC1014129 DOI: 10.1136/jnnp.53.3.208] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The reflex EMG responses from a tendon tap or an imposed, medium amplitude (30 degrees), stretch at a range of stretch velocities have been recorded from the triceps and biceps muscles of normal human subjects and in both the affected and "unaffected" arms of hemiparetic patients under relaxed conditions. In the hemiparetic arm, exaggerated tendon jerks were, as expected, observed in both muscles. The response of the biceps to elbow extension was also exaggerated compared with normal values and displayed both an additional earlier component and a much reduced velocity threshold. The triceps, in contrast, showed depressed responses to elbow flexion, with a much higher velocity threshold than normal subjects. Furthermore, on the supposedly "unaffected" side of the hemiparetic subjects, the reciprocal pattern was seen, with depression of the biceps response and a raising of its threshold, along with considerably exaggerated responses in the triceps including earlier components not seen in the normal subjects. The increased excitability of the flexor musculature on the spastic side may be paralleled by increases in activity in the segmental pathways responsible for modulation of agonist/antagonist activity in the ipsi and contralateral limb, leading to an inhibition of the ipsilateral extensors and contralateral flexors and excitatory input to the contralateral extensors. Thus the "good" side of hemiparetic patients also receives pathological changes, and studies of the mechanisms of spasticity should avoid the use of the "unaffected" side of hemiparetic subjects as a control for monitoring pathological reflexes.
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Affiliation(s)
- A F Thilmann
- Department of Neurology and Clinical Neurophysiology, Alfried Krupp Krankenhaus, Essen, Federal Republic of Germany
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Abbruzzese M, Reni L, Favale E. Neurographic assessment of central delay changes in the H reflex pathway: a new test of spinal function in man. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY. SUPPLEMENT 1990; 41:73-83. [PMID: 2289455 DOI: 10.1016/b978-0-444-81352-7.50011-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- M Abbruzzese
- Department of Neurology, University of Genoa, Italy
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Dawson NJ, Lippold OC, Milne RJ. Contralateral intramuscular acupuncture-like electrical stimulation differentially changes the short-latency responses to muscle stretch. Exp Neurol 1987; 98:41-53. [PMID: 3653333 DOI: 10.1016/0014-4886(87)90070-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Measurements were made from the human first dorsal interosseous and extensor digitorum communis muscles of the surface electromyographic activity reflexly produced by brief stretch of the muscle. For the first dorsal interosseous muscle, reflex EMG activity was also produced by electrical stimulation of the ulnar nerve at the wrist. The procedures were carried out before, during, and after 25 min of nonspecific, low-frequency electrical stimulation to the contralateral arm delivered through intramuscular electrodes. Control stimulation was delivered subcutaneously. The EMG recorded during a maintained contraction was rectified, filtered, and averaged. Two reflex components (M1 and M2) of the EMG response to muscle stretch or ulnar nerve stimulation were investigated. During nonspecific intramuscular stimulation to the contralateral arm, M1 responses of the extensor digitorum communis were depressed, initially by 37%. The effect began to fade during stimulation but extended beyond it. Reflex responses were elicited alternately by brief stretch of the first dorsal interosseus muscle and by electrical stimulation of the ulnar nerve in the same experiment. Nonspecific intramuscular stimulation to the contralateral arm depressed the M1 response to stretch, but had no effect on the M1 response to electrical stimulation. It is concluded that nonspecific intramuscular electrical stimulation reduces the amplitude of the M1 component of the response to brief stretch of contralateral muscle, either through depression of fusimotor activity or inhibition of oligosynaptic pathways that contribute to the early reflex response.
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Affiliation(s)
- N J Dawson
- Department of Physiology, School of Medicine, University of Auckland, New Zealand
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Abstract
Empirical and theoretical reasons were given to investigate operant conditioning in a new, integrative approach within motor control physiology. Elements of inborn and learned behavior were presented in a framework specifying their stimuli and responses. The operant was redefined as a controlling discriminative stimulus, Sd, together with the response, R, it produces, on the basis of a previous literature of operant and instrumental research. Complex motor and neural activity were reviewed in accordance with partitioning of: responses, controlling stimulation, reinforcement, and functions of movement-produced stimulation. Schematics portrayed reinforcement principles through analysis of a fast pathway from Ia muscle spindle afferents to motor outflow. Methods were suggested to minimize operant units through selective reinforcement and establish them to defined end points of learning within composite, ongoing behavior. It was argued that operant neural mechanisms can be investigated efficiently only by starting with individual operants that are thoroughly characterized.
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Ratto S, Reni L, Abbruzzese G, Abbruzzese M, Favale E. Facilitation and inhibition of synaptic transmission in the spinal cord: an electroneurographic study in humans. Exp Brain Res 1986; 64:411-20. [PMID: 3026829 DOI: 10.1007/bf00340478] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The neurographic activity evoked either by stimulation of the tibial nerve at the popliteal fossa or by percussion of the Achilles tendon has been recorded at lumbar and thigh levels, in order to find out whether conduction time, temporal dispersion and central delay of the neural volleys underlying the monosynaptic reflex (H or T) may change as a function of stimulus intensity; under facilitatory or inhibitory experimental conditions; "spontaneously", i.e. during the steady state. The reflexly evoked ventral root discharge (VRD) decreases in latency with increasing stimulus intensity up to the maximum reflex response in the absence of changes in afferent (thigh to spine) or efferent (spine to thigh) conduction times. Reduction of the central delay was greater with mechanical than electrical stimulation, probably due to the combined effect of spatial and temporal summation under the former experimental condition. The latency of the VRD related to the maximal H response was not further modified by supramaximal stimulus strengths. The Jendrassik manoeuvre caused a significant decrease in latency of the VRD, the opposite effect being observed during calf muscle vibration. A significant relationship between amplitude and latency of single VRDs could be demonstrated during the "steady state". Our data point to the existence of a positive correlation between the size of the motoneuronal pool activated by an afferent volley and speed of transmission in the reflex pathway, both during the "steady state" and under either facilitatory or inhibitory experimental conditions, provided that the test stimulus strength does not exceed the maximum reflex response (H or T). No detectable signs of peripheral dispersion of the VRD could be demonstrated, irrespective of the stimulus employed: this suggests that the axon diameters of the motoneurones contributing to the monosynaptic reflex fall within a fairly narrow distribution.
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Scheirs JG, Brunia CH. Motor preparation and the Achilles tendon reflex: the role of background muscle tension. Biol Psychol 1986; 23:163-78. [PMID: 3790653 DOI: 10.1016/0301-0511(86)90080-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The effects of instructed tension or relaxation of the soleus muscles on the amplitude of the Achilles tendon reflex were investigated. Reflexes were evoked during the foreperiod of a warned reaction time experiment with a plantar flexion of the right foot serving as the response, and during isometric contractions of the right soleus muscle at different low levels of tension. The tension levels were related to the subject's maximal voluntary contraction force. The results were comparable in the two tasks. When background muscle tension was present in the right leg the reflexes in that leg were depressed, whereas in the contralateral leg reflexes were increased. This difference in amplitude was roughly proportional to the amount of tension and independent of whether the antagonist muscle was also activated during the contraction. It was argued that the differential reflex effect found in the two soleus muscles during motor preparation need not be a reflection of a selective neural inhibition. It could also be explained by a reduced effectiveness of the tendon tap in stretching the muscle, due to stiffening of the muscle during contraction. It was concluded that during motor preparation, only reflex changes recorded in the absence of muscle tension can be considered reflections of subliminal changes in spinal reactivity.
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Abbruzzese M, Ratto S, Abbruzzese G, Favale E. Electroneurographic correlates of the monosynaptic reflex: experimental studies and normative data. J Neurol Neurosurg Psychiatry 1985; 48:434-44. [PMID: 3998752 PMCID: PMC1028330 DOI: 10.1136/jnnp.48.5.434] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The neurographic concomitants of the monosynaptic reflex, evoked either by electrical stimulation of the tibial nerve at the popliteal fossa or by percussion of the Achilles tendon, have been recorded from the sciatic nerve in the lower and middle thigh. Neurographic recordings were characterised by two travelling waves (P1 and P2), respectively increasing and decreasing in latency in the proximal direction, that showed the same chronological trend of the propagated action potentials concurrently recorded in the dorsal and ventral spinal roots at the lumbar level. At variance with P2, the speed of propagation of the P1 volley was stimulus-related, being faster on mechanical than on electrical stimulation, probably because in the latter case the latency of the fastest afferents is overestimated. The P2 volley is subserved by alpha-efferent fibres in either case as suggested, inter alia, by the strict parallelism between the P2 volley and the monosynaptic reflex under appropriate experimental conditions. Simultaneous recordings of spinal root and sciatic nerve action potentials allowed the direct assessment of afferent and efferent conduction velocities, both in the proximal (that is from the middle thigh to the spinal recording site and vice-versa) and in the distal (that is from the lower to the middle thigh recording site and vice versa) segments of the reflex arc. As expected, the speed of propagation of impulses was significantly higher in the proximal than in the distal segments, as well as in the afferent than in efferent limb of the monosynaptic pathway. The P1-P2 time interval was longer on mechanical than on electrical stimulation, probably due to the increased spinal delay of the T versus the H reflex. The present study provides a reliable method for the direct assessment of alpha-efferent as well as of Ia afferent group fibres conduction velocity, provided that in the latter case mechanical stimuli be used.
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Delwaide PJ. Electrophysiological analysis of the mode of action of muscle relaxants in spasticity. Ann Neurol 1985; 17:90-5. [PMID: 3985591 DOI: 10.1002/ana.410170119] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Variations in four electrophysiological tests (H/M, T/M, vibratory inhibition, and recovery curve of Hoffmann's reflex following stimulation at the ankle) were studied following a single administration of four myorelaxant drugs: diazepam (10 mg intramuscularly), baclofen (20 mg intramuscularly), tizanidine (4 mg orally), and idrocilamide (60 mg intramuscularly). Fifty-one spastic patients, divided into four groups, were tested. All four drugs reduced the H/M and T/M ratios very slightly. Only diazepam and tizanidine reinforced vibratory inhibition. Diazepam and tizanidine did not modify the abnormal recovery curves, however, whereas baclofen and idrocilamide did. Reinforcement of vibratory inhibition suggests an increase in presynaptic inhibition mediated by gamma-aminobutyric acid; changes in recovery curves are likely due to modifications of interneuronal reactivity. Matching myorelaxants to the predominant pathophysiological abnormality detected by electrophysiological exploration may lead to better treatment of spasticity.
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Morgan DL, Prochazka A, Proske U. Can fusimotor activity potentiate the responses of muscle spindles to a tendon tap? Neurosci Lett 1984; 50:209-15. [PMID: 6238244 DOI: 10.1016/0304-3940(84)90488-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Experiments on the cat soleus muscle have determined the effect of selective activation of the fusimotor system on the responses of muscle receptors to a simulated tendon tap. Primary endings of spindles responded in the passive muscle with an average 4.3 impulses at a mean instantaneous rate of 502 impulses/s. Static fusimotor stimulation at 100 pulses/s increased the number of impulses during the tap to 4.8 but dropped the mean instantaneous rate to 400 impulses/s. Dynamic fusimotor stimulation increased the number of impulses to 6.3 and the instantaneous rate to 557 impulses/s. Combined stimulation of the two axons gave intermediate values. We consider these effects as rather feeble. The tendon jerk in man shows a large increase in reflex amplitude following a reinforcement manoeuvre (Jendrassik manoeuvre). Based on our animal experiments we conclude that such increases cannot be accounted for simply in terms of selective engagement of the fusimotor system.
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Eichenberger A, Rüegg DG. Relation between the specific H reflex facilitation preceding a voluntary movement and movement parameters in man. J Physiol 1984; 347:545-59. [PMID: 6707967 PMCID: PMC1199463 DOI: 10.1113/jphysiol.1984.sp015082] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In a reaction-time situation, the monosynaptic spinal reflex (H reflex) is facilitated before the onset of an electromyographic (e.m.g.) response. The aim of the present investigation was to study aspects of this facilitation. Human subjects were required to perform isometric plantarflexions of the foot in response to a visual stimulus. The movement was always on the same side in the simple reaction-time situation, and randomly with the right or left foot in the choice reaction-time situation. Stimuli to evoke H reflexes were applied bilaterally 40-400 ms after the onset of the visual stimulus. Pre-motor time, i.e. the interval between the onset of the visual stimulus and the e.m.g. response, and reaction time, i.e. the interval between the onset of the visual stimulus and the response on the torque recording, were computed. In both reaction-time situations, there was a significant facilitation of the ipsilateral H reflex 100-160 ms before e.m.g. onset and, in some subjects, a small facilitation of the contralateral H reflex. The specific facilitation, i.e. the difference between the facilitation on the ipsi- and contralateral side relative to the movement, was not significantly different on the right and left side. Pre-motor time was divided into the interval from the light onset until the onset of the specific facilitation, and the interval from the onset of the facilitation until the onset of the voluntary response. Both intervals increased, and the slope and the amplitude of the facilitation decreased with increasing pre-motor time and reaction time. The specificity of the H reflex facilitation in a choice reaction-time situation implies that the interval from light onset until the onset of the facilitation includes stimulus identification and response selection, and the interval from the onset of the facilitation until the e.m.g. response preparation of the motor system for the required movement. The present results suggest that the specific facilitation of the H reflex before a movement is caused by removal of presynaptic inhibition at I a terminals or by activation of interneurones intercalated in polysynaptic components of the H reflex rather than by a subthreshold activation of motoneurones.
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Burke D, McKeon B, Skuse NF. The irrelevance of fusimotor activity to the Achilles tendon jerk of relaxed humans. Ann Neurol 1981; 10:547-50. [PMID: 6459756 DOI: 10.1002/ana.410100609] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In two normal subjects the sciatic nerve was blocked completely using concentrated lidocaine. The muscle afferent and reflex electromyographic responses to reproducible percussion of the Achilles tendon were recorded while the blocks developed. The intensity of percussion was sufficient to produce an Achilles tendon jerk in one subject when at rest and in the other during reinforcement. The block did not alter the muscle afferent response to tendon percussion in either subject. It is concluded that background fusimotor activity is not a prerequisite for the tendon jerk and that, during complete relaxation, there may be no significant fusimotor drive directed to the triceps surae. The varying ease with which tendon jerks can be elicited in different normal subjects or in different muscles of the same subject appears to be related not to fusimotor activity but to differences in the "central excitability state."
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