Increase in group II excitation from ankle muscles to thigh motoneurones during human standing
| Autor: | Marchand-Pauvert, Véronique, Nicolas, Guillaume, Marque, Philippe, Iglesias, Caroline, Pierrot-Deseilligny, Emmanuel |
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| Přispěvatelé: | Physiologie et physiopathologie de la motricité chez l'homme, Université Pierre et Marie Curie - Paris 6 (UPMC)-IFR70-Institut National de la Santé et de la Recherche Médicale (INSERM) |
| Jazyk: | angličtina |
| Rok vydání: | 2005 |
| Předmět: |
Adult
Reflex Stretch Posture MESH: Musculoskeletal Equilibrium MESH: Ankle Integrative Physiology Humans MESH: Reflex Stretch Muscle Skeletal Muscle Spindles Postural Balance Aged Motor Neurons MESH: Aged MESH: Muscle Skeletal MESH: Humans MESH: Middle Aged [SDV.BA.MVSA]Life Sciences [q-bio]/Animal biology/Veterinary medicine and animal Health MESH: Adult MESH: Posture Middle Aged musculoskeletal system Adaptation Physiological MESH: Adaptation Physiological Thigh Ankle MESH: Muscle Spindles MESH: Motor Neurons MESH: Thigh |
| Zdroj: | The Journal of Physiology The Journal of Physiology, 2005, 566 (Pt 1), pp.257-71. ⟨10.1113/jphysiol.2005.087817⟩ The Journal of Physiology, Wiley, 2005, 566 (Pt 1), pp.257-71. ⟨10.1113/jphysiol.2005.087817⟩ |
| ISSN: | 0022-3751 1469-7793 |
| DOI: | 10.1113/jphysiol.2005.087817⟩ |
| Popis: | International audience; In standing subjects, we investigated the excitation of quadriceps (Q) motoneurones by muscle afferents from tibialis anterior (TA) and the excitation of semitendinosus (ST) motoneurones by muscle afferents from gastrocnemius medialis (GM). Standing with a backward lean stretches the anterior muscle pair (TA and Q) and they must be co-contracted to maintain balance. Equally, forward lean stretches the posterior muscle pair (GM and ST) and they must be co-contracted. We used these conditions of enhanced lean to increase the influence of gamma static motoneurones on muscle spindle afferents, which enhances the background input from these afferents to extrafusal motoneurones. The effects of the conditioning volleys on motoneurone excitability was estimated using the modulation of the on-going rectified EMG and of the H reflex. Stimulation of afferents from TA in the deep peroneal nerve at 1.5-2 x MT (motor threshold) evoked early group I and late group II excitation of Q motoneurones. Stimulation of afferents in the GM nerve at 1.3-1.8 MT evoked only late group II excitation of ST motoneurones. The late excitation produced by the group II afferents was significantly greater when subjects were standing and leaning than when they voluntarily co-contracted the same muscle pairs at the same levels of activation. The early effect produced by the group I afferents was unchanged. We propose that this increase in excitation by group II afferents reflects a posture-related withdrawal of a tonic inhibition that is exerted by descending noradrenergic control and is specific to the synaptic actions of group II afferents. |
| Databáze: | OpenAIRE |
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