Neural Control of Rhythmic Human Arm Movement: Phase Dependence and Task Modulation of Hoffmann Reflexes in Forearm Muscles

2003 ◽  
Vol 89 (1) ◽  
pp. 12-21 ◽  
Author(s):  
E. Paul Zehr ◽  
David F. Collins ◽  
Alain Frigon ◽  
Nienke Hoogenboom
Keyword(s):  
Neural Control ◽  
Arm Movement ◽  
H Reflex ◽  
Neural Mechanisms ◽  
Emg Activity ◽  
Reflex Amplitude ◽  
Forearm Muscles ◽  
Custom Made ◽  
Static Contraction ◽  
Leg Movement

Although we move our arms rhythmically during walking, running, and swimming, we know little about the neural control of such movements. Our working hypothesis is that neural mechanisms controlling rhythmic movements are similar in the human lumbar and cervical spinal cord. Thus reflex modulation during rhythmic arm movement should be similar to that seen during leg movement. Our main experimental hypotheses were that the amplitude of H-reflexes in the forearm muscles would be modulated during arm movement (i.e., phase-dependent) and would be inhibited during cycling compared with static contraction (i.e., task-dependent). Furthermore, to determine the locus of any modulation, we tested the effect that active and passive movement of the ipsilateral (relative to stimulated arm) and contralateral arm had on H-reflex amplitude. Subjects performed rhythmic arm cycling on a custom-made hydraulic ergometer in which the two arms could be constrained to move together (180° out of phase) or could rotate independently. Position of the stimulated limb in the movement cycle is described with respect to the clock face. H-reflexes were evoked at 12, 3, 6, and 9 o'clock positions during static contraction as well as during rhythmic arm movements. Reflex amplitudes were compared between tasks at equal M wave amplitudes and similar levels of electromyographic (EMG) activity in the target muscle. Surface EMG recordings were obtained bilaterally from flexor carpi radialis as well as from other muscles controlling the wrist, elbow, and shoulder. Compared with reflexes evoked during static contractions, movement of the stimulated limb attenuated H-reflexes by 50.8% ( P < 0.005), 65.3% ( P < 0.001), and 52.6% ( P < 0.001) for bilateral, active ipsilateral, and passive ipsilateral movements, respectively. In contrast, movement of the contralateral limb did not significantly alter H-reflex amplitude. H-reflexes were also modulated by limb position ( P < 0.005). Thus task- and phase-dependent modulation were observed in the arm as previously demonstrated in the leg. The data support the hypothesis that neural mechanisms regulating reflex pathways in the moving limb are similar in the human upper and lower limbs. However, the inhibition of H-reflex amplitude induced by contralateral leg movement is absent in the arms. This may reflect the greater extent to which the arms can be used independently.

Effect of afferent feedback and central motor commands on soleus H-reflex suppression during arm cycling

2012 ◽  
Vol 108 (11) ◽  
pp. 3049-3058 ◽  
Author(s):  
S. R. Hundza ◽  
Geoff C. de Ruiter ◽  
M. Klimstra ◽  
E. Paul Zehr
Keyword(s):  
Primary Source ◽  
Arm Movement ◽  
H Reflex ◽  
Afferent Feedback ◽  
Reflex Modulation ◽  
Muscle Vibration ◽  
Reflex Amplitude ◽  
Motor Commands ◽  
Arm Cycling ◽  
Central Motor Commands

Suppression of soleus H-reflex amplitude in stationary legs is seen during rhythmic arm cycling. We examined the influence of various arm-cycling parameters on this interlimb reflex modulation to determine the origin of the effect. We previously showed the suppression to be graded with the frequency of arm cycling but not largely influenced by changes in peripheral input associated with crank length. Here, we more explicitly explored the contribution of afferent feedback related to arm movement on the soleus H-reflex suppression. We explored the influence of load and rate of muscle stretch by manipulating crank-load and arm-muscle vibration during arm cycling. Furthermore, internally driven (“Active”) and externally driven (“Passive”) arm cycling was compared. Soleus H-reflexes were evoked with tibial nerve stimulation during stationary control and rhythmic arm-cycling conditions, including: 1) six different loads; 2) with and without vibration to arm muscles; and 3) Active and Passive conditions. No significant differences were seen in the level of suppression between the different crank loads or between conditions with and without arm-muscle vibration. Furthermore, in contrast to the clear effect seen during active cycling, passive arm cycling did not significantly suppress the soleus H-reflex amplitude. Current results, in conjunction with previous findings, suggest that the afferent feedback examined in these studies is not the primary source responsible for soleus H-reflex suppression. Instead, it appears that central motor commands (supraspinal or spinal in origin) associated with frequency of arm cycling are relatively more dominant sources.

Possible contributions of CPG activity to the control of rhythmic human arm movement

2004 ◽  
Vol 82 (8-9) ◽  
pp. 556-568 ◽  
Author(s):  
E Paul Zehr ◽  
Timothy J Carroll ◽  
Romeo Chua ◽  
David F Collins ◽  
Alain Frigon ◽  
...  
Keyword(s):  
Motor Control ◽  
Neural Control ◽  
Arm Movement ◽  
Rhythmic Movement ◽  
Lower Limbs ◽  
Reflex Modulation ◽  
Arm Cycling ◽  
Reflex Reversal ◽  
Arm Muscles ◽  
Leg Movement

There is extensive modulation of cutaneous and H-reflexes during rhythmic leg movement in humans. Mechanisms controlling reflex modulation (e.g., phase- and task-dependent modulation, and reflex reversal) during leg movements have been ascribed to the activity of spinal central pattern generating (CPG) networks and peripheral feedback. Our working hypothesis has been that neural mechanisms (i.e., CPGs) controlling rhythmic movement are conserved between the human lumbar and cervical spinal cord. Thus reflex modulation during rhythmic arm movement should be similar to that for rhythmic leg movement. This hypothesis has been tested by studying the regulation of reflexes in arm muscles during rhythmic arm cycling and treadmill walking. This paper reviews recent studies that have revealed that reflexes in arm muscles show modulation within the movement cycle (e.g., phase-dependency and reflex reversal) and between static and rhythmic motor tasks (e.g., task-dependency). It is concluded that reflexes are modulated similarly during rhythmic movement of the upper and lower limbs, suggesting similar motor control mechanisms. One notable exception to this pattern is a failure of contralateral arm movement to modulate reflex amplitude, which contrasts directly with observations from the leg. Overall, the data support the hypothesis that CPG activity contributes to the neural control of rhythmic arm movement.Key words: central pattern generator, locomotion, motor control, neural control.

Robotic-assisted stepping modulates monosynaptic reflexes in forearm muscles in the human

2011 ◽  
Vol 106 (4) ◽  
pp. 1679-1687 ◽  
Author(s):  
Tsuyoshi Nakajima ◽  
Taku Kitamura ◽  
Kiyotaka Kamibayashi ◽  
Tomoyoshi Komiyama ◽  
E. Paul Zehr ◽  
...  
Keyword(s):  
Suppressive Effect ◽  
H Reflex ◽  
Afferent Feedback ◽  
Quiet Standing ◽  
Reflex Amplitude ◽  
Robotic Assisted ◽  
Forelimb Muscles ◽  
Leg Movement ◽  
Gait Trainer ◽  
Body Loading

Although the amplitude of the Hoffmann (H)-reflex in the forelimb muscles is known to be suppressed during rhythmic leg movement, it is unknown which factor plays a more important role in generating this suppression—movement-related afferent feedback or feedback related to body loading. To specifically explore the movement- and load-related afferent feedback, we investigated the modulation of the H-reflex in the flexor carpi radialis (FCR) muscle during robotic-assisted passive leg stepping. Passive stepping and standing were performed using a robotic gait-trainer system (Lokomat). The H-reflex in the FCR, elicited by electrical stimulation to the median nerve, was recorded at 10 different phases of the stepping cycle, as well as during quiet standing. We confirmed that the magnitude of the FCR H-reflex was suppressed significantly during passive stepping compared with during standing. The suppressive effect on the FCR H-reflex amplitude was seen at all phases of stepping, irrespective of whether the stepping was conducted with body weight loaded or unloaded. These results suggest that movement-related afferent feedback, rather than load-related afferent feedback, plays an important role in suppressing the FCR H-reflex amplitude.

Neural mechanisms of soleus H-reflex depression accompanying voluntary arm movement in standing humans

1999 ◽  
Vol 832 (1-2) ◽  
pp. 13-22 ◽  
Author(s):  
Masayuki Kawanishi ◽  
Susumu Yahagi ◽  
Tatsuya Kasai
Keyword(s):  
Arm Movement ◽  
H Reflex ◽  
Neural Mechanisms ◽  
Standing Humans

Corticospinal Excitability Is Lower During Rhythmic Arm Movement Than During Tonic Contraction

2006 ◽  
Vol 95 (2) ◽  
pp. 914-921 ◽  
Author(s):  
Timothy J. Carroll ◽  
Evan R. L. Baldwin ◽  
David F. Collins ◽  
E. Paul Zehr
Keyword(s):  
Motor Cortex ◽  
Neural Control ◽  
Motor Evoked Potentials ◽  
Arm Movement ◽  
Voluntary Contraction ◽  
Tonic Contraction ◽  
H Reflex ◽  
Corticospinal Excitability ◽  
Arm Cycling ◽  
Subcortical Regions

Humans perform rhythmic, locomotor movements with the arms and legs every day. Studies using reflexes to probe the functional role of the CNS suggest that spinal circuits are an important part of the neural control system for rhythmic arm cycling and walking. Here, by studying motor-evoked potentials (MEPs) in response to transcranial magnetic stimulation (TMS) of the motor cortex, and H-reflexes induced by electrical stimulation of peripheral nerves, we show a reduction in corticospinal excitability during rhythmic arm movement compared with tonic, voluntary contraction. Responses were compared between arm cycling and tonic contraction at four positions, while participants generated similar levels of muscle activity. Both H-reflexes and MEPs were significantly smaller during arm cycling than during tonic contraction at the midpoint of arm flexion ( F = 13.51, P = 0.006; F = 11.83, P = 0.009). Subthreshold TMS significantly facilitated the FCR H-reflex during tonic contractions, but did not significantly modulate H-reflex amplitude during arm cycling. The data indicate a reduction in the responsiveness of cells constituting the fast, monosynaptic, corticospinal pathway during arm cycling and suggest that the motor cortex may contribute less to motor drive during rhythmic arm movement than during tonic, voluntary contraction. Our results are consistent with the idea that subcortical regions contribute to the control of rhythmic arm movements despite highly developed corticospinal projections to the human upper limb.

Differential Control of Reciprocal Inhibition During Walking Versus Postural and Voluntary Motor Tasks in Humans

1997 ◽  
Vol 78 (1) ◽  
pp. 429-438 ◽  
Author(s):  
Brigitte A. Lavoie ◽  
Hervé Devanne ◽  
Charles Capaday
Keyword(s):  
Reaction Time ◽  
Motor Activity ◽  
Reciprocal Inhibition ◽  
Swing Phase ◽  
Voluntary Contraction ◽  
H Reflex ◽  
Quiet Standing ◽  
Emg Activity ◽  
Reflex Amplitude ◽  
Differential Control

Lavoie, Brigitte A., Hervé Devanne, and Charles Capaday. Differential control of reciprocal inhibition during walking versus postural and voluntary motor tasks in humans. J. Neurophysiol. 78: 429–438, 1997. Experiments were done to determine whether the strength of reciprocal inhibition from ankle flexors to extensors can be controlled independently of the level of ongoing motor activity in a task-dependent manner. In this paper we use the term reciprocal inhibition in the functional sense—inhibition of the antagonist(s) during activity of the agonist(s)—without reference to specific neural pathways that may be involved. The strength of reciprocal inhibition of the soleus α-motoneurons was determined by measuring the amplitude of the H reflex during voluntary, postural, and locomotor tasks requiring activity of the ankle flexor tibialis anterior (TA). Differences in the strength of reciprocal inhibition between tasks were determined from plots of the soleus H reflex amplitude versus the mean value of the TA electromyogram (EMG). Additionally, in tasks involving movement, the correlation between the H reflex amplitude and the joint kinematics was calculated. In most subjects (15 of 22) the soleus H reflex decreased approximately linearly with increasing tonic voluntary contractions of the TA. The H reflex also decreased approximately linearly with the TA EMG activity when subjects where asked to lean backward. There were no statistical differences between the regression lines obtained in these tasks. In some subjects (7 of 22), however, the H reflex amplitude was independent of the level of TA EMG activity, except for a sudden drop at high levels of TA activity (∼60–80% of maximum voluntary contraction). The type of relation between the soleus H reflex and the TA EMG activity in these tasks was not correlated with the maximum H reflex to maximum M wave ( H max/ M max) ratio measured during quiet standing. In marked contrast, during the swing phase of walking—over the same range of TA EMG activity as during the tonic voluntary contraction task—the H reflex was reduced to zero in most subjects (24 of 31). In seven subjects the H reflex during the swing phase was reduced to some 5% of the value during quiet standing. The same result was found when subjects were asked to produce a stepping movement with one leg (OLS) in response to an auditory “go” signal. Additionally, in the OLS task it was possible to examine the behavior of the H reflex during the reaction time and thus to evaluate the relative contribution of central commands versus movement-related afferent activity to the inhibition of the soleus H reflex. In 11 of 12 subjects the H reflex attained its minimum value before either the onset of EMG activity or movement of any of the leg joints. It is significant that the H reflex was most powerfully inhibited during the swing phase of walking and the closely related OLS task. The H reflex was also measured during isolated ankle dorsiflexion movements. The subjects were asked to track a target displayed on a computer screen with dorsiflexion movements of the ankle. The trajectory of the target was the same as that of the ankle during the swing phase of walking. The soleus H reflexes were intermediate in size between the values obtained in the tonic contraction task and the walking or OLS tasks. A negative, but weak, correlation ( r 2 < 0.68) between the soleus H reflex and the TA EMG was found in 3 of 10 subjects. Furthermore, there was no correlation between the H reflex amplitude and the ankle angular displacement or angular velocity. In this task, as in the OLS task, the H reflex began to decrease during the reaction time before the onset of TA EMG activity. We conclude that the strength of reciprocal inhibition of the soleus α-motoneuron pool can thus be controlled independently of the level of motor activity in the ankle flexors. The strength of the inhibition of the antagonist(s) depends on the task, and for each task the strength of the inhibition is not necessarily proportional to the level of motor activity in the agonist(s). Additionally, the evidence suggests a strong central contribution to these task-dependent changes, because the inhibition of the H reflex is essentially completed during the reaction time before the onset of EMG activity or joint movement. The possible neural mechanisms involved in the task-dependent control of reciprocal inhibition are treated in the discussion.

scholarly journals Neural control of rhythmic arm cycling after stroke

2012 ◽  
Vol 108 (3) ◽  
pp. 891-905 ◽  
Author(s):  
E. Paul Zehr ◽  
Pamela M. Loadman ◽  
Sandra R. Hundza
Keyword(s):  
Neural Control ◽  
Arm Movement ◽  
Constant Current ◽  
Cycle Phase ◽  
Emg Activity ◽  
Reflex Modulation ◽  
Cutaneous Reflexes ◽  
Cutaneous Reflex ◽  
Arm Cycling ◽  
Modulation Pattern

Disordered reflex activity and alterations in the neural control of walking have been observed after stroke. In addition to impairments in leg movement that affect locomotor ability after stroke, significant impairments are also seen in the arms. Altered neural control in the upper limb can often lead to altered tone and spasticity resulting in impaired coordination and flexion contractures. We sought to address the extent to which the neural control of movement is disordered after stroke by examining the modulation pattern of cutaneous reflexes in arm muscles during arm cycling. Twenty-five stroke participants who were at least 6 mo postinfarction and clinically stable, performed rhythmic arm cycling while cutaneous reflexes were evoked with trains (5 × 1.0-ms pulses at 300 Hz) of constant-current electrical stimulation to the superficial radial (SR) nerve at the wrist. Both the more (MA) and less affected (LA) arms were stimulated in separate trials. Bilateral electromyography (EMG) activity was recorded from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted on averaged reflexes in 12 equidistant phases of the movement cycle. Phase-modulated cutaneous reflexes were present, but altered, in both MA and LA arms after stroke. Notably, the pattern was “blunted” in the MA arm in stroke compared with control participants. Differences between stroke and control were progressively more evident moving from shoulder to wrist. The results suggest that a reduced pattern of cutaneous reflex modulation persists during rhythmic arm movement after stroke. The overall implication of this result is that the putative spinal contributions to rhythmic human arm movement remain accessible after stroke, which has translational implications for rehabilitation.

scholarly journals Enhancement of Arm and Leg Locomotor Coupling With Augmented Cutaneous Feedback From the Hand

2007 ◽  
Vol 98 (3) ◽  
pp. 1810-1814 ◽  
Author(s):  
E. Paul Zehr ◽  
Marc Klimstra ◽  
Katie Dragert ◽  
Yasaman Barzi ◽  
Mark G. Bowden ◽  
...  
Keyword(s):  
Significant Contribution ◽  
Movement Control ◽  
Suppressive Effect ◽  
Cycle Ergometer ◽  
H Reflex ◽  
Reflex Amplitude ◽  
Cutaneous Feedback ◽  
Leg Cycling ◽  
Leg Movement ◽  
Stimulation Of

Cutaneous feedback from the hand could assist with coordination between the arms and legs during locomotion. Previously we used a reduced walking model of combined arm and leg (arm&leg) cycling to examine the separate effects of rhythmic arm (arm) and leg (leg) movement. Here we use this same paradigm to test the modulation H-reflexes with and without interlimb cutaneous conditioning evoked by stimulating a nerve innervating the hand (superficial radial, SR). It was hypothesized that both arm and leg would contribute significantly to suppression of H-reflex amplitude during arm&leg. We also predicted a conservation of interlimb cutaneous conditioning during movement and an interaction between arm and leg rhythmic movement control. Subjects were seated in a recumbent arm&leg cycle ergometer and maintained a low-level soleus contraction for all tasks. H-reflex amplitude was facilitated by cutaneous conditioning evoked by stimulation of the SR nerve. H-reflex amplitudes were taken from recruitment curves and included modulation of 50% Hmax and Hmax. The suppressive effect of arm was less than that for leg and arm&leg, while suppression during leg and arm&leg were generally equivalent. For H-reflexes conditioned by cutaneous input, amplitudes during arm&leg instead were in between those for arm and leg modulation. Multiple regression analysis revealed a significant contribution for arm only in trials when SR stimulation was used to condition H-reflex amplitudes. We suggest that there is a measurable interaction between neural activity regulating arm and leg movement during locomotion that is specifically enhanced when cutaneous input from the hand is present.

Effect of Rhythmic Arm Movement on Reflexes in the Legs: Modulation of Soleus H-Reflexes and Somatosensory Conditioning

2004 ◽  
Vol 91 (4) ◽  
pp. 1516-1523 ◽  
Author(s):  
Alain Frigon ◽  
David F. Collins ◽  
E. Paul Zehr
Keyword(s):  
Spinal Cord ◽  
Nerve Stimulation ◽  
Presynaptic Inhibition ◽  
Arm Movement ◽  
Common Peroneal Nerve ◽  
H Reflex ◽  
Reflex Amplitude ◽  
Lumbosacral Spinal Cord ◽  
Arm Cycling ◽  
Shoulder Flexion

During locomotor tasks such as walking, running, and swimming, the arms move rhythmically with the legs. It has been suggested that connections between the cervical and lumbosacral spinal cord may mediate some of this interlimb coordination. However, it is unclear how these interlimb pathways modulate reflex excitability during movement. We hypothesized that rhythmic arm movement would alter the gain of reflex pathways in the stationary leg. Soleus H-reflexes recorded during arm cycling were compared with those recorded at similar positions with the arms stationary. Nerve stimulation was delivered with the right arm at approximately 70° shoulder flexion or 10° shoulder extension. H-reflexes were evoked alone (unconditioned) or with sural or common peroneal nerve (CP) conditioning to decrease or increase soleus IA presynaptic inhibition, respectively. Both conditioning stimuli were also delivered with no H-reflex stimulation. H-reflex amplitudes were compared at similar M-wave amplitudes and activation levels of the soleus. Arm cycling significantly reduced ( P < 0.05) unconditioned soleus H-reflexes at shoulder flexion by 21.7% and at shoulder extension by 8.8% compared with static controls. The results demonstrate a task-dependent modulation of soleus H-reflexes between arm cycling and stationary trials. Sural nerve stimulation facilitated H-reflexes at shoulder extension but not at shoulder flexion during static and cycling trials. CP nerve stimulation significantly reduced H-reflex amplitude in all conditions. Reflexes in soleus when sural and CP nerve stimulation were delivered alone, were not different between cycling and static trials; thus the task-dependent change in H reflex amplitude was not due to changes in motoneuron excitability. Therefore modulation occurred at a pre-motoneuronal level, probably by presynaptic inhibition of the IA afferent volley. Results indicate that neural networks coupling the cervical and lumbosacral spinal cord in humans are activated during rhythmic arm movement. It is proposed that activation of these networks may assist in reflex linkages between the arms and legs during locomotor tasks.

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