Changes in H-Reflex Amplitude During Massage of Triceps Surae in Healthy Subjects

1. Study of memory traces in higher animals requires experimental models possessing well-localized and technically accessible memory traces--plasticity responsible for behavioral change, not dependent on control from elsewhere, and open to detailed investigation. Our purpose has been to develop such a model based on the wholly spinal, largely monosynaptic path of the spinal stretch reflex. Previous studies described operant conditioning of this reflex and of its electrical analog, the H-reflex. In this study, we sought to determine whether conditioning causes changes in the spinal cord that affect the reflex and are not dependent on continued supraspinal influence, and thus qualify as memory traces. 2. Sixteen monkeys underwent chronic conditioning of the triceps surae H-reflex. Eight were rewarded for increasing H-reflex amplitude (HR increases mode), and eight were rewarded for decreasing it (HR decreases mode). In each animal, the other leg was an internal control. Over several months of conditioning, H-reflex amplitude in the conditioned leg rose in HR increases animals and fell in HR decreases animals. H-reflex amplitude in the control leg changed little. 3. After HR increases or HR decreases conditioning, each animal was deeply anesthetized and surgically prepared. The reflex response to supramaximal dorsal root stimulation was measured from the triceps surae nerve as percent of response to supramaximal ventral root stimulation, which was the maximum possible response. Data from both legs were collected before and for up to 3 days after thoracic (T9-10) cord transection. The animal remained deeply anesthetized throughout and was killed by overdose. 4. The reflex asymmetries produced by conditioning were still present several days after transection removed supraspinal influence: reflexes of HR increases animals were significantly larger in HR increases legs than in control legs and reflexes of HR decreases animals were significantly smaller in HR decreases legs than in control legs. 5. Reflex amplitude was much greater in the control legs of anesthetized HR decreases animals than in the control legs of anesthetized HR increases animals. 6. Chronic conditioning had at least two effects on the spinal cord. The first effect, task-appropriate reflex asymmetry, was evident both in the awake behaving animal and in the anesthetized transected animal. The second effect, larger control leg reflexes in HR decreases than in HR increases animals, was evident only in the anesthetized animal. By removing supraspinal control, anesthesia and transection revealed a previously hidden effect of conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)

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Operant conditioning of primate spinal reflexes: the H-reflex

Journal of Neurophysiology ◽

10.1152/jn.1987.57.2.443 ◽

1987 ◽

Vol 57 (2) ◽

pp. 443-459 ◽

Cited By ~ 93

Author(s):

J. R. Wolpaw

Keyword(s):

Operant Conditioning ◽

H Reflex ◽

Spinal Reflexes ◽

Triceps Surae ◽

Spinal Reflex ◽

Control Mode ◽

Response Threshold ◽

Reflex Amplitude ◽

Emg Amplitude ◽

Spinal Stretch Reflex

The study of primate memory substrates, the CNS alterations which preserve conditioned responses, requires an experimental model that fulfills two criteria. First, the essential alterations must be in a technically accessible location. Second, they must persist without input from other CNS regions. The spinal cord is the most technically accessible and readily isolated portion of the primate CNS. Recent work has demonstrated that the spinal stretch reflex (SSR), the initial, wholly segmental response to muscle stretch, can be operantly conditioned and suggests that this conditioning may produce persistent spinal alteration. The present study attempted similar operant conditioning of the H-reflex, the electrical analog of the SSR. The primary goals were to demonstrate that spinal reflex conditioning can occur even if the muscle spindle is removed from the reflex arc and to demonstrate conditioning in the lumbosacral cord, which is far preferable to the cervical cord for future studies of neuronal and synaptic mechanisms. Nine monkeys prepared with chronic fine-wire triceps surae (gastrocnemius and soleus) electromyographic (EMG) electrodes were taught by computer to maintain a given level of background EMG activity. At random times, a voltage pulse just above M response (direct muscle response) threshold was delivered to the posterior tibial nerve via a chronically implanted silicon nerve cuff and elicited the triceps surae H-reflex. Under the control mode, reward always followed. Under the HR increases or HR decreases mode, reward followed only if the absolute value of triceps surae EMG from 12 to 22 ms after the pulse (the H-reflex interval) was above (HR increases) or below (HR decreases) a set value. Monkeys completed 3,000-6,000 trials/day over study periods of 2-3 mo. Background EMG and M response amplitude remained stable throughout data collection. H-reflex amplitude remained stable under the control mode. Under the HR increases mode (5 animals) or HR decreases mode (4 animals), H-reflex amplitude (EMG amplitude in the H-reflex interval minus background EMG amplitude) changed appropriately over at least 6 wk. Change appeared to occur in two phases: an abrupt change within the first day, followed by slower change, which continued indefinitely. Change occurred in all three triceps surae muscles (medial and lateral gastrocnemii and soleus). Under the HR increases mode, H-reflex amplitude rose to an average of 213% of control, whereas under the HR decreases mode it fell to an average of 68% of control. The results demonstrate that the H-reflex can be operantly conditioned.(ABSTRACT TRUNCATED AT 400 WORDS)

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Sway-dependent modulation of the triceps surae H-reflex during standing

Journal of Applied Physiology ◽

10.1152/japplphysiol.00857.2007 ◽

2008 ◽

Vol 104 (5) ◽

pp. 1359-1365 ◽

Cited By ~ 31

Author(s):

Craig D. Tokuno ◽

S. Jayne Garland ◽

Mark G. Carpenter ◽

Alf Thorstensson ◽

Andrew G. Cresswell

Keyword(s):

Postural Sway ◽

Center Of Pressure ◽

H Reflex ◽

Triceps Surae ◽

Quiet Standing ◽

Electromyographic Activity ◽

Experimental Conditions ◽

Reflex Amplitude ◽

Independent Effects ◽

Spinal Excitability

Previous research has shown that changes in spinal excitability occur during the postural sway of quiet standing. In the present study, it was of interest to examine the independent effects of sway position and sway direction on the efficacy of the triceps surae Ia pathway, as reflected by the Hoffman (H)-reflex amplitude, during standing. Eighteen participants, tested under two different experimental protocols, stood quietly on a force platform. Percutaneous electrical stimulation was applied to the posterior tibial nerve when the position and direction of anteroposterior (A-P) center of pressure (COP) signal satisfied the criteria for the various experimental conditions. It was found that, regardless of sway position, a larger amplitude of the triceps surae H-reflex (difference of 9–14%; P = 0.005) occurred when subjects were swaying in the forward compared with the backward direction. The effects of sway position, independent of the sway direction, on spinal excitability exhibited a trend ( P = 0.075), with an 8.9 ± 3.7% increase in the H-reflex amplitude occurring when subjects were in a more forward position. The observed changes to the efficacy of the Ia pathway cannot be attributed to changes in stimulus intensity, as indicated by a constant M-wave amplitude, or to the small changes in the level of background electromyographic activity. One explanation for the changes in reflex excitability with respect to the postural sway of standing is that the neural modulation may be related to the small lengthening and shortening contractions occurring in the muscles of the triceps surae.

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New evidence of corticospinal network modulation induced by motor imagery

Journal of Neurophysiology ◽

10.1152/jn.00952.2015 ◽

2016 ◽

Vol 115 (3) ◽

pp. 1279-1288 ◽

Cited By ~ 26

Author(s):

Sidney Grosprêtre ◽

Florent Lebon ◽

Charalambos Papaxanthis ◽

Alain Martin

Keyword(s):

Evoked Potentials ◽

Motor Imagery ◽

Motor Evoked Potentials ◽

Static Condition ◽

Mental Simulation ◽

Voluntary Contraction ◽

H Reflex ◽

Triceps Surae ◽

Subcortical Structures ◽

Reflex Amplitude

Motor imagery (MI) is the mental simulation of movement, without the corresponding muscle contraction. Whereas the activation of cortical motor areas during MI is established, the involvement of spinal structures is still under debate. We used original and complementary techniques to probe the influence of MI on spinal structures. Amplitude of motor-evoked potentials (MEPs), cervico-medullary-evoked potentials (CMEPs), and Hoffmann (H)-reflexes of the flexor carpi radialis (FCR) muscle and of the triceps surae muscles was measured in young, healthy subjects at rest and during MI. Participants were asked to imagine maximal voluntary contraction of the wrist and ankle, while the targeted limb was fixed (static condition). We confirmed previous studies with an increase of FCR MEPs during MI compared with rest. Interestingly, CMEPs, but not H-reflexes, also increased during MI, revealing a possible activation of subcortical structures. Then, to investigate the effect of MI on the spinal network, we used two techniques: 1) passive lengthening of the targeted muscle via an isokinetic dynamometer and 2) conditioning of H-reflexes with stimulation of the antagonistic nerve. Both techniques activate spinal inhibitory presynaptic circuitry, reducing the H-reflex amplitude at rest. In contrast, no reduction of H-reflex amplitude was observed during MI. These findings suggest that MI has modulatory effects on the spinal neuronal network. Specifically, the activation of low-threshold spinal structures during specific conditions (lengthening and H-reflex conditioning) highlights the possible generation of subliminal cortical output during MI.

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Human soleus H-reflex excitability is decreased by dynamic head-and-body tilts

Journal of Vestibular Research ◽

10.3233/ves-1999-9507 ◽

1999 ◽

Vol 9 (5) ◽

pp. 379-383

Author(s):

Nicole Paquet ◽

Christina W.Y. Hui-Chan

Keyword(s):

Healthy Subjects ◽

Stretch Reflex ◽

H Reflex ◽

Quiet Standing ◽

Head Acceleration ◽

Reflex Amplitude ◽

Reflex Excitability ◽

Dynamic Head ◽

Reflex Arc

The modulation of soleus (SO) H-reflex excitability during dynamic whole head-and-body tilts (WHBT) was investigated in normal healthy subjects. Between 30 and 70 ms, and 151 and 190 ms after head acceleration onset, the H-reflex amplitude was smaller than during quiet standing by 7.6% ( p < 0.01) and 15.4% ( p = 0.06) respectively. This finding suggested that dynamic WHBT reduced the excitability of the predominantly monosynaptic stretch reflex arc in the majority of the subjects studied.

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Long-lasting depression of soleus motoneurons excitability following repetitive magnetic stimuli of the spinal cord in multiple sclerosis patients

Multiple Sclerosis Journal ◽

10.1177/135245859700300103 ◽

1997 ◽

Vol 3 (1) ◽

pp. 18-30 ◽

Cited By ~ 33

Author(s):

Jørgen F Nielsen ◽

Thomas Sinkjær

Keyword(s):

Healthy Subjects ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

H Reflex ◽

Reflex Amplitude ◽

Repetitive Magnetic Stimulation ◽

Limb Spasticity ◽

Lower Limb Spasticity ◽

Multiple Sclerosis Patients

The effect of repetitive magnetic stimulation at the spinal level on the soleus H-reflex amplitude was evaluated in II MS patients with lower limb spasticity and in nine healthy subjects. In MS patients stimulation with a train of 16 stimuli at 25 Hz induced a decrease in amplitude to 61.2 ± 25.7% of the unconditioned H-reflex amplitude at interstimulus interval (ISI) of 10 - 1000 ms (P < 0.0 1). The amount of decrease in H-reflex amplitude was highly dependent on the stimulation intensity and the placement of the coil, and to a lesser extent influenced by the stimulation frequency. No decrease in motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation was seen following trains of 16 stimuli at mid-thoracic in contrast to the post-stimulation depression in H-reflex amplitude which could imply that mechanisms acting at presynaptic level were involved. In response to repetitive magnetic stimuli for 5 min, a long-lasting decrease in H-reflex amplitude to a level of about 70% of the pre-stimulation H-reflex amplitude occurred in MS patients (P< 0.01 ). A similar although not significant decrease was observed in healthy subjects. We propose that long-lasting depression of the soleus H-reflex amplitude after repetitive magnetic stimuli is due to long-term depression of the synaptic transmission.

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Acute Effects of Kinesiology Taping Stretch Tensions on Soleus and Gastrocnemius H-Reflex Modulations

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18094411 ◽

2021 ◽

Vol 18 (9) ◽

pp. 4411

Author(s):

Yung-Sheng Chen ◽

Shi Zhou ◽

Zachary J. Crowley-McHattan ◽

Pedro Bezerra ◽

Wei-Chin Tseng ◽

...

Keyword(s):

H Reflex ◽

Triceps Surae ◽

Reflex Modulation ◽

Hoffmann Reflex ◽

Acute Effects ◽

Physically Active ◽

M Wave ◽

Subject Design ◽

Minor Influence ◽

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This study examined the acute effects of stretch tensions of kinesiology taping (KT) on the soleus (SOL), medial (MG), and lateral (LG) gastrocnemius Hoffmann-reflex (H-reflex) modulation in physically active healthy adults. A cross-over within-subject design was used in this study. Twelve physically active collegiate students voluntarily participated in the study (age = 21.3 ± 1.2 years; height = 175.6 ± 7.1 cm; body weight = 69.9 ± 7.1 kg). A standard Y-shape of KT technique was applied to the calf muscles. The KT was controlled in three tension intensities in a randomised order: paper-off, 50%, and 100% of maximal stretch tension of the tape. The peak-to-peak amplitude of maximal M-wave (Mmax) and H-reflex (Hmax) responses in the SOL, MG, and LG muscles were assessed before taping (pre-taping), taping, and after taping (post-taping) phases in the lying prone position. The results demonstrated significantly larger LG Hmax responses in the pre-taping condition than those in the post-taping condition during paper-off KT (p = 0.002). Moreover, the ΔHmax/Mmax of pre- and post-taping in the SOL muscle was significantly larger during 50%KT tension than that of paper-off (p = 0.046). In conclusion, the stretch tension of KT contributes minor influence on the spinal motoneuron excitability in the triceps surae during rest.

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