Control of Ia afferent input to triceps surae (soleus) locomotor nucleus precedes agonist muscle activation during gait

Leis, A. Arturo; Grubwieser, Gert J.; Schild, John H.; West, Mark; Stokić, Dobrivoje S.

doi:10.1016/1050-6411(94)00008-a

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…The testing leg was secured by a Velcro strap around the foot to maintain a fixed position on the platform attached to the compressor system. It is known that the excitability of motor neurons is influenced by central set, characterized as the “preparatory set” within the central nervous system before execution of a motor act (Frank, 1986; Meunier and Pierrot-Deseilligny, 1989; Leis et al, 1995). The central set is affected by many factors such as environmental noise (Delwaide and Schepens, 1995; Kolev and Milanov, 1995), the level of arousal and anxiety(Ribot-Ciscar et al, 2000; Rossi-Durand, 2002; Sibley et al, 2007), body position (Hayashi et al, 1992; Mynark and Koceja, 1997; Phadke et al, 2006), and sensory inputs (Iles and Pisini, 1992b; Hoffman and Koceja, 1995; Iles, 1996; Knikou, 2007; Conway and Knikou, 2008).…”

Section: Methodsmentioning

confidence: 99%

Limb segment load inhibits post activation depression of soleus H-reflex in humans

Tseng

Shields

2012

Clinical Neurophysiology

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Objective We investigated the effect of various doses of limb segment load on soleus H-reflex amplitude and post activation depression in healthy individuals. We also explored the influence of limb segment load on spinal circuitry in one individual with chronic SCI. Methods 28 healthy adults and one SCI subject received compressive loads applied to the top of their knee at varied doses of load (10%, 25%, and 50% of the body weight). Soleus H-reflexes were measured before (baseline) and during the loading phase. Results There were no significant differences in H-reflex amplitudes during the 50 % BW load-on phase as compared to either baseline session or the load-off phase. However, the post activation depression was decreased over 9% (p < 0.05) during the load-on phase compared to the load-off phase and scaled according to load (50%>25%>10%). The post activation depression ratio also appears less responsive to varying loads after chronic SCI. Conclusions Limb segment load decreases post-activation depression in humans. These findings suggest that the mechanism associated with post activation depression is modulated by limb segment load, and may be influenced by spinal reorganization after SCI. Significance Future studies will determine if various levels of spasticity modulate the response of limb segment load on post activation depression in those with acute and chronic SCI.

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Section: Methodsmentioning

confidence: 99%

Limb segment load inhibits post activation depression of soleus H-reflex in humans

Tseng

Shields

2012

Clinical Neurophysiology

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“…The first (direct descending pathway) conveys signals along the efferent motor fibers that generate muscle contraction by direct motoneuron depolarization. The second (indirect ascending pathway) communicates signals via the afferent sensory fibers (Collins, 2007) that code proprioceptive signals from muscle spindles, Golgi tendon organs and cutaneous receptors (Burke et al, 1983), but in particular Ia fibers responsible for muscle spindle information (Leis et al, 1995). This second pathway produces muscle contractions through a central mechanism, providing excitatory synaptic input to spinal neurons that recruit motor units in the natural order (Bergquist et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Re-thinking the role of motor cortex: Context-sensitive motor outputs?

et al. 2014

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The standard account of motor control considers descending outputs from primary motor cortex (M1) as motor commands and efference copy. This account has been challenged recently by an alternative formulation in terms of active inference: M1 is considered as part of a sensorimotor hierarchy providing top–down proprioceptive predictions. The key difference between these accounts is that predictions are sensitive to the current proprioceptive context, whereas efference copy is not. Using functional electric stimulation to experimentally manipulate proprioception during voluntary movement in healthy human subjects, we assessed the evidence for context sensitive output from M1. Dynamic causal modeling of functional magnetic resonance imaging responses showed that FES altered proprioception increased the influence of M1 on primary somatosensory cortex (S1). These results disambiguate competing accounts of motor control, provide some insight into the synaptic mechanisms of sensory attenuation and may speak to potential mechanisms of action of FES in promoting motor learning in neurorehabilitation.

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Behavior of the H-reflex in humans following mechanical perturbation or injury to rostral spinal cord

Leis

Zhou²,

Mehta

et al. 1996

Muscle Nerve

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Control of Ia afferent input to triceps surae (soleus) locomotor nucleus precedes agonist muscle activation during gait

Cited by 3 publications

References 21 publications

Limb segment load inhibits post activation depression of soleus H-reflex in humans

Limb segment load inhibits post activation depression of soleus H-reflex in humans

Re-thinking the role of motor cortex: Context-sensitive motor outputs?

Behavior of the H-reflex in humans following mechanical perturbation or injury to rostral spinal cord

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