Modulation of the Hoffmann reflex in the tibialis anterior with a change in posture

Unger, Janelle; Andrushko, Justin W.; Oates, Alison; Renshaw, Doug; Barss, Trevor S.; Zehr, E. Paul; Farthing, Jonathan P.

doi:10.14814/phy2.14179

Cited by 4 publications

(3 citation statements)

References 33 publications

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“…In our study, participants stood on one leg, with the ankle in a neutral position and the knee and hip joints almost fully extended. This increased postural demand (as in the transition from lying to standing or bipedal to unipedal standing) has been shown to be accompanied by modulation of soleus and tibialis H‐reflex amplitudes 35–37 . More precisely, increases in postural demand were correlated with decreases in reflex amplitudes.…”

Section: Discussionmentioning

confidence: 96%

“…This increased postural demand (as in the transition from lying to standing or bipedal to unipedal standing) has been shown to be accompanied by modulation of soleus and tibialis H-reflex amplitudes. [35][36][37] More precisely, increases in postural demand were correlated with decreases in reflex amplitudes. The proposed mechanism behind this presynaptic inhibition is a shift in the central nervous system to increase voluntary balance control.…”

Section: Postural Muscle Reflexesmentioning

confidence: 92%

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Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

Hellmann,

Fadillioglu,

Kanus

et al. 2024

J of Oral Rehabilitation

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BackgroundJaw clenching improves dynamic reactive balance on an oscillating platform during forward acceleration and is associated with decreased mean sway speed of different body regions.ObjectiveIt is suggested that jaw clenching as a concurrent muscle activity facilitates human motor excitability, increasing the neural drive to distal muscles. The underlying mechanism behind this phenomenon was studied based on leg and trunk muscle activity (iEMG) and co‐contraction ratio (CCR).MethodsForty‐eight physically active and healthy adults were assigned to three groups, performing three oral motor tasks (jaw clenching, tongue pressing against the palate or habitual lower jaw position) during a dynamic one‐legged stance reactive balance task on an oscillating platform. The iEMG and CCR of posture‐relevant muscles and muscle pairs were analysed during platform forward acceleration.ResultsTongue pressing caused an adjustment of co‐contraction patterns of distal muscle groups based on changes in biomechanical coupling between the head and trunk during static balancing at the beginning of the experiment. Neither iEMG nor CCR measurement helped detect a general neuromuscular effect of jaw clenching on the dynamic reactive balance.ConclusionThe findings might indicate the existence of robust fixed patterns of rapid postural responses during the important initial phases of balance recovery.

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Section: Discussionmentioning

confidence: 96%

Section: Postural Muscle Reflexesmentioning

confidence: 92%

Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

Hellmann,

Fadillioglu,

Kanus

et al. 2024

J of Oral Rehabilitation

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“…The phase-dependent reflex behaviour in certain leg muscles that occurs as a result of cutaneous electrical stimulation during walking [30] could be found in individuals who were only passively sitting and observing the walking movement of another person [28]. Since psychophysiological changes in the peripheral and central systems can occur in a seated viewer compared to an upright observer [31], this result was not necessarily to be expected. In this respect, the seated posture certainly has a strong influence on the accessibility of the motor representation.…”

Section: Introductionmentioning

confidence: 99%

Influence of combined action observation and motor imagery of walking on lower limb reflex modulation in patients after stroke–preliminary results

2022

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Objective The combined use of action observation and motor imagery (AOMI) is a promising technique in neurorehabilitation that can be usefully applied in addition to conventional forms of therapy. Previous studies with healthy participants showed that the mere passive observation of walking results in a phase-dependent reflex modulation in the tibialis anterior muscle that resembles the pattern occurring when walking. In patients after stroke, a similar reflex modulation was found in several lower limb muscles during the real execution of walking, but responses were blunted. To clarify whether and how lower limb reflex responses are also modulated in such patients during the combined synchronous observation and imagery of walking, medium-latency cutaneous reflexes from the tibialis anterior muscle were measured. We compared the reflex responses of seven patients after stroke during the AOMI of walking from two different conditions: (a) elicited during the end stance phase and (b) during the end swing phase, both normalized to a baseline condition. Results So far, using the identical methodological set-up as in our study with healthy individuals, we could not find any noteworthy reflex response modulation. The study was registered with the German Clinical Trials Register (DRKS00028255). Trial registration : The study was registered with the German Clinical Trials Register: DRKS00028255.

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Estimates of persistent inward currents in tibialis anterior motor units during standing ramped contraction tasks in humans

Khurram

Negro

Heckman

et al. 2021

Journal of Neurophysiology

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Persistent inward currents (PICs) play an essential role in setting motor neuron gain and shaping motor unit firing patterns. Estimates of PICs in humans can be made using the paired motor unit analysis technique, which quantifies the difference in discharge rate of a lower-threshold motor unit at the recruitment onset and offset of a higher-threshold motor unit (∆F). Because PICs are highly dependent on the level of neuromodulatory drive, ∆F represents an estimate of level of neuromodulation at the level of the spinal cord. Most of the estimates of ∆F are performed under constrained, isometric, seated conditions. In the present study, we used high-density surface EMG arrays to discriminate motor unit firing patterns during isometric seated conditions with torque or EMG visual feedback and during unconstrained standing anterior-to-posterior movements with RMS EMG visual feedback. We were able to apply the paired motor unit analysis technique to the decomposed motor units in each of the three conditions. We hypothesized that ∆F would be higher during unconstrained standing anterior-to-posterior movements compared to the seated conditions, reflecting an increase in the synaptic input to MNs drive while standing. In agreement with previous work, we found that there was no evidence of a difference in ∆F between the seated and standing postures, although slight differences in the initial and peak discharge rates were observed. Taken together, our results suggest that both the standing and seated postures are likely not sufficiently different--both being "upright" postures--to result in large changes in neuromodulatory drive.

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Modulation of the Hoffmann reflex in the tibialis anterior with a change in posture

Cited by 4 publications

References 33 publications

Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

Influence of combined action observation and motor imagery of walking on lower limb reflex modulation in patients after stroke–preliminary results

Estimates of persistent inward currents in tibialis anterior motor units during standing ramped contraction tasks in humans

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