Monosynaptic Ia excitation and recurrent inhibition from quadriceps to ankle flexors and extensors in man.

Meunier, Sabine; Pénicaud, Anne; Pierrot-Deseilligny, E; Rossi, Alessandro

doi:10.1113/jphysiol.1990.sp018046

Cited by 102 publications

(108 citation statements)

References 16 publications

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“…These studies along with our findings suggest that the strength of reciprocal Ia and presynaptic inhibition is influenced by afferents of distal and proximal muscles and that some heteronymous connections postulated in healthy subjects (Meunier et al 1990) are preserved following SCI.…”

Section: Hip-induced Modulation Of Spinal Inhibitory Mechanismsmentioning

confidence: 68%

Effects of hip joint angle changes on intersegmental spinal coupling in human spinal cord injury

Knikou

2005

Exp Brain Res

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Pathological expression of movement and muscle tone in human upper motor neuron disorders has been partly associated with impaired modulation of spinal inhibitory mechanisms, such as reciprocal or presynaptic inhibition. In addition, input from specific afferent systems contributes significantly to spinal reflex circuits coupled with posture or locomotion. Accordingly, the objectives of this study were to identify the involved afferents and their relative contribution to soleus H-reflex modulation induced by changes in hip position, and to relate these effects with activity of spinal interneuronal circuits. Specifically, we investigated the actions of group I synergistic and antagonistic muscle afferents (e.g. common peroneal nerve, CPN; medial gastrocnemius, MG) and tactile plantar cutaneous afferents on the soleus H-reflex during controlled hip angle variations in 11 motor incomplete spinal cord injured (SCI) subjects. It has been postulated in healthy subjects that CPN stimulation evokes an inhibition on the soleus H-reflex at a conditioning test (C-T) interval of 2-4 ms. This short latency reflex depression is caused mainly by activation of the reciprocal Ia inhibitory pathway. At longer C-T intervals (beyond 30 ms) the soleus H-reflex is again depressed, and is generally accepted to be caused by presynaptic inhibition of soleus Ia afferents. Similarly, MG nerve stimulation depresses soleus H-reflex excitability at the C-T interval of 6 ms, involving the pathway of non-reciprocal group I inhibition, while excitation of plantar cutaneous afferents affects the activity of spinal reflex pathways in the extensors. In this study, soleus H-reflexes recorded alone or during CPN stimulation at either short (2, 3, 4 ms) or long (80, 100, 120 ms) C-T intervals, and MG nerve stimulation delivered at 6 ms were elicited via conventional methods and similar to those adopted in studies conducted in healthy subjects. Plantar skin conditioning stimulation was delivered through two surface electrodes placed on the metatarsals at different C-T intervals ranging from 3 to 90 ms. CPN stimulation at either short or long C-T intervals and MG nerve stimulation resulted in a significant facilitation of the soleus H-reflex, regardless of the hip angle tested. Plantar skin stimulation delivered with hip extended at 10° induced a bimodal facilitation reflex pattern, while with hip flexed (10°, 30°) the reflex facilitation increased with increments in the C-T interval. This study provides evidence that in human chronic SCI, classically key inhibitory reflex actions are switched to facilitatory, and that spinal processing of plantar cutaneous sensory input and actions of synergistic/antagonistic muscle afferents interact with hip proprioceptive input to facilitate soleus H-reflex excitability. These actions might be associated with the pathological expression of neural control of movement in individuals with SCI, and potentially could be considered in rehabilitation programs geared to restore sensorimotor function in these patien...

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Section: Hip-induced Modulation Of Spinal Inhibitory Mechanismsmentioning

confidence: 68%

Effects of hip joint angle changes on intersegmental spinal coupling in human spinal cord injury

Knikou

2005

Exp Brain Res

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“…Recurrent inhibition has been reported to be preserved in humans after SCI, 27 and although RF stimulation at 2 Â MT will provoke antidromic activation of motor axons, the time course of recurrent inhibition (B30 ms) is too brief to account for the long lasting reflex depression observed. 28,29 Hence, postsynaptic inhibition resulting from direct electrical stimulation of afferent or efferent axons is unlikely to be a major factor in the depression seen in the LLFR.…”

Section: Discussionmentioning

confidence: 99%

Effects of electrically induced muscle contraction on flexion reflex in human spinal cord injury

Knikou

Conway

2005

Spinal Cord

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Study design: Flexion reflex study in motor complete human spinal cord injury (SCI). Objectives: To examine changes in the magnitude of the flexion reflex following functional electrical stimulation (FES) of the rectus femoris (RF) muscle. Setting: Bioengineering Unit, University of Strathclyde, Glasgow, Scotland, UK. Methods: The flexion reflex was evoked by electrical stimulation of the sural nerve, and was recorded in the tibialis anterior (TA) muscle. RF muscle conditioning stimulation was performed at 0.7, 1, and 2 times motor threshold ( Â MT) over a range of conditioning test intervals.Results: The incidence of the early component of the flexion reflex (o100 ms) was low, suggesting that this reflex component might be suppressed in SCI. The long latency flexion reflex component (4120 ms) was observed in all subjects during control conditions and following sensorimotor conditioning. FES applied to the RF muscle (above and below MT) in the main induced a significant early and long lasting depression of the long latency flexion reflex. Conclusion: The depression of the flexion reflex was a result of multisensory actions on flexion reflex pathways resulting from the direct and indirect (mechanical) consequences of electrically induced muscle contraction on cutaneous and muscle afferents. Our findings emphasize the importance of sensory feedback mechanisms in modulating flexion reflex excitability, and highlight the need for rehabilitation professionals to consider the central actions of FES-induced afferent feedback when incorporating FES into a rehabilitation program. Sponsorship: State Scholarships Foundation (IKY) of Hellas.Spinal Cord (2005) 43, 640-648.

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“…Coupling effects are also put forward by the observation that not all possible phase relations of reflex modulation between muscle groups occurred with the same odds. Influences affecting different motoneuron pools may arise from interconnections of myotatic reflex arcs (Cheng et al 1995;Delwaide et al 1976;Meunier et al 1990) as well as crossed spinal connections (Koceja and Kamen 1992;Mezzarane and Kohn 2002). For instance, recurrent inhibition of Ia inhibitory interneurons would periodically release antagonistic motoneurons from their tonic inhibitory activity, a phenomenon known as recurrent facilitation (Hultborn et al 1971b;Pierrot-Desseilligny and Burke 2012).…”

Section: Discussionmentioning

confidence: 99%

Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord

Hofstoetter

Danner

Freundl

et al. 2015

Journal of Neurophysiology

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Hofstoetter US, Danner SM, Freundl B, Binder H, Mayr W, Rattay F, Minassian K. Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord. J Neurophysiol 114: 400 -410, 2015. First published April 22, 2015 doi:10.1152/jn.00136.2015.-In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22-60 Hz can generate rhythmic burstlike activity. Here we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elicited reflexes alternating between large and small. We analyzed responses concomitantly elicited in thigh and leg muscle groups bilaterally by epidural stimulation in eight motor-complete spinal cord-injured individuals. Periodic amplitude modulation of at least 20 successive responses occurred in 31.4% of all available data sets with stimulation frequency set at 5-26 Hz, with highest prevalence at 16 Hz. It could be evoked in a single muscle group only but was more strongly expressed and consistent when occurring in pairs of antagonists or in the same muscle group bilaterally. Latencies and waveforms of the modulated reflexes corresponded to those of the unmodulated, monosynaptic responses to 2-Hz stimulation. We suggest that the cyclical changes of reflex excitability resulted from the interaction of facilitatory and inhibitory mechanisms emerging after specific delays and with distinct durations, including postactivation depression, recurrent inhibition and facilitation, as well as reafferent feedback activation. The emergence of large responses within the patterns at a rate of 5.5/s or 8/s may further suggest the entrainment of spinal mechanisms as involved in clonus. The study demonstrates that the human lumbosacral spinal cord can organize a simple form of rhythmicity through the repetitive activation of spinal reflex circuits.

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Monosynaptic Ia excitation and recurrent inhibition from quadriceps to ankle flexors and extensors in man.

Cited by 102 publications

References 16 publications

Effects of hip joint angle changes on intersegmental spinal coupling in human spinal cord injury

Effects of hip joint angle changes on intersegmental spinal coupling in human spinal cord injury

Effects of electrically induced muscle contraction on flexion reflex in human spinal cord injury

Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord

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