Ia presynaptic inhibition in human wrist extensor muscles: Effects of motor task and cutaneous afferent activity

Aimonetti, Jean Marc; Schmied, Annie; Vedel, Jean‐Pierre; Pagni, Simone

doi:10.1016/s0928-4257(00)80067-4

Cited by 20 publications

(16 citation statements)

References 30 publications

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“…Electrical and mechanical stimuli may also have different effects on the input received from cutaneous and muscle afferents during the force and position tasks. The feedback transmitted by these afferents has been shown to modulate the level of presynaptic inhibition during a variety of motor tasks (reviewed in Aimonetti et al, 1999;Meunier, 1999;Rudomin, 2002).…”

Section: Discussionmentioning

confidence: 99%

Reflex responsiveness of a human hand muscle when controlling isometric force and joint position

Maluf

Barry

Riley

et al. 2007

Clinical Neurophysiology

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Objective-This study compared reflex responsiveness of the first dorsal interosseus muscle during two tasks that employ different strategies to stabilize the finger while exerting the same net muscle torque.Methods-Healthy human subjects performed two motor tasks that involved either pushing up against a rigid restraint to exert a constant isometric force equal to 20% of maximum, or maintaining a constant angle at the metacarpophalangeal joint while supporting an equivalent inertial load. Each task consisted of six 40-s contractions during which electrical and mechanical stimuli were delivered.Results-The amplitude of short and long latency reflex responses to mechanical stretch did not differ significantly between tasks. In contrast, reflexes evoked by electrical stimulation were significantly greater when supporting the inertial load.Conclusions-Agonist motor neurons exhibited heightened reflex responsiveness to synaptic input from heteronymous afferents when controlling the position of an inertial load. Task differences in the reflex response to electrical stimulation were not reflected in the response to mechanical perturbation, indicating a difference in the efficacy of the pathways that mediate these effects.Significance-Results from this study suggest that modulation of spinal reflex pathways may contribute to differences in the control of force and position during isometric contractions of the first dorsal interosseus muscle.

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Section: Discussionmentioning

confidence: 99%

Reflex responsiveness of a human hand muscle when controlling isometric force and joint position

Maluf

Barry

Riley

et al. 2007

Clinical Neurophysiology

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“…First, the sensitivity of the monosynaptic reflex to excitatory and inhibitory inputs, which depends on the size of the reflex (Crone et al 1990), was controlled by adjusting the intensity of the stimulation to standardize the amplitude of the test H reflex (relative to its corresponding M max ) at the beginning of the two fatiguing contractions. Second, weak stimulation of cutaneous afferents from the hand depresses the amount of presynaptic inhibition exerted on the Ia afferents converging onto the ECR motor neuron pool (Aimonetti et al 1999). In our experimental conditions, only the back of the hand was in contact with the device, and this was similar contact during the force and position tasks.…”

Section: Methodological Considerationsmentioning

confidence: 99%

“…Electrical stimulation (Grass S88K, Astra-Med, West Warwick, RI, 1-ms rectangular pulse) was used to elicit test H reflexes and to provide conditioning stimuli that produced either D1 inhibition (Aimonetti et al 1999) or heteronymous Ia facilitation . Stimuli were delivered via a constant-current unit (model CCU1, Astra-Med) that was connected to adhesive surface electrodes (Conmed, Utica, NY) placed in a bipolar configuration.…”

Section: Electrical Stimulationmentioning

confidence: 99%

“…D1 inhibition. The test H reflex was conditioned by a stimulus applied to the median nerve to activate PAD interneurons responsible for presynaptic inhibition of the Ia afferents from the ECR (Aimonetti et al 1999;Berardelli et al 1987). The delay between median (conditioning stimulus) and radial (test stimulus) nerve stimuli that produced the greatest depression of the H reflex amplitude was determined for each participant by 5-ms increments from 5 to 30 ms.…”

Section: Test H Reflexes and Conditioned H Reflexesmentioning

confidence: 99%

“…An electrical stimulus was applied to the palmar branch of the median nerve at the level of the wrist to evoke monosynaptic (heteronymous) facilitation of the motor neuron pool of the ECR . As only the first 0.5 ms of the heteronymous facilitation arises from monosynaptic Ia afferent inputs (Aimonetti et al 1999), the onset of heteronymous Ia facilitation of the H reflex in the ECR in response to stimulation of the palmar branch of the median nerve (1.0 ϫ motor threshold) was established from an initial interval of 4 ms between the conditioning and test stimuli that was changed in 1-ms increments and then 0.2-ms increments. An increase of 5-10% in the amplitude of the conditioned H reflex relative to the test H reflex was used to identify the onset of the facilitation.…”

Section: Test H Reflexes and Conditioned H Reflexesmentioning

confidence: 99%

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Task- and time-dependent modulation of Ia presynaptic inhibition during fatiguing contractions performed by humans

Baudry

Maerz

Gould

et al. 2011

Journal of Neurophysiology

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Differential modulation of primary afferent depolarization of segmental and ascending intraspinal collaterals of single muscle afferents in the cat spinal cord

Rudomín

Lomelí

Quevedo

2004

Experimental Brain Research

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We examined primary afferent depolarization (PAD) in the anesthetized cat elicited in 109 pairs of intraspinal collaterals of single group I afferents from the gastrocnemius nerve, one of the pair ending in the L3 segment, around the Clarke's column nuclei, and the other in the L6 segment within the intermediate zone. Tests for refractoriness were made to assess whether the responses produced by intraspinal stimulation in the L3 and L6 segments were due to activation of collaterals of the same afferent fiber. PAD in each collateral was estimated by independent computer-controlled measurement of the intraspinal current required to maintain a constant probability of antidromic firing. In most fibers, stimulation of the ipsilateral posterior biceps and semitendinosus (PBSt) nerve with trains of pulses maximal for group I afferents had a qualitatively similar effect but produced a larger PAD in the L6 than in the L3 collaterals. Stimulation of cutaneous nerves (sural and superficial peroneus) with single pulses and of the posterior articular nerve, the ipsilateral reticular formation, nucleus raphe magnus and contralateral motor cortex with trains of pulses often had qualitatively different effects. They could produce PAD and/or facilitate the PBSt-induced PAD in one collateral, and produce PAH and/or inhibit the PAD in the other collateral. These patterns could be changed in a differential manner by sensory or supraspinal conditioning stimulation. In summary, the present investigation suggests that the segmental and ascending collaterals of individual afferents are not fixed routes for information transmission, but parts of dynamic systems in which information transmitted to segmental reflex pathways and to Clarke's column neurons by common sources can be decoupled by sensory and descending inputs and funneled to specific targets according to the motor tasks to be performed.

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Ia presynaptic inhibition in human wrist extensor muscles: Effects of motor task and cutaneous afferent activity

Cited by 20 publications

References 30 publications

Reflex responsiveness of a human hand muscle when controlling isometric force and joint position

Reflex responsiveness of a human hand muscle when controlling isometric force and joint position

Task- and time-dependent modulation of Ia presynaptic inhibition during fatiguing contractions performed by humans

Differential modulation of primary afferent depolarization of segmental and ascending intraspinal collaterals of single muscle afferents in the cat spinal cord

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