Understanding exercise-dependent plasticity of motoneurons using intracellular and intramuscular approaches

Abstract

Spinal motoneurons (MN) exhibit exercise-dependent adaptations to increased activity, such as exercise and locomotion, as well as decreased activity associated with disuse, spinal cord injury, and aging. The development of several experimental approaches, in both human and animal models, has contributed significantly to our understanding of this plasticity. The purpose of this review is to summarize how intracellular recordings in an animal model and motor unit recordings in a human model have, together, contributed to our current understanding of exercise-dependent MN plasticity. These approaches and techniques will allow neuroscientists to continue to advance our understanding of MN physiology and the plasticity of the "final common path" of the motor system, and to design experiments to answer the critical questions that are emerging in this field.Résumé : Les motoneurones spinaux (MN) présentent des adaptations liées à l'augmentation de l'activité telle qu'à l'exercice physique et à la locomotion et d'autres adaptations à diminution de l'activité associée à la désuétude, aux lésions médullaires et au vieillissement. Le développement de plusieurs approches expérimentales à la fois chez l'homme et chez l'animal a grandement contribué à notre compréhension de cette plasticité. Le but de cette analyse documentaire est de présenter de façon sommaire comment les enregistrements intracellulaires dans un modèle animal et les enregistrements d'unités motrices dans un modèle humain ont ensemble favoriser notre compréhension actuelle de la plasticité du MN liée à l'exercice. Ces approches et techniques permettront aux neuroscientifiques de continuer à approfondir la compréhension de la physiologie du MN et de la plasticité de la « voie commune terminale » du système moteur ainsi que de concevoir des expérimentations pour répondre aux questions critiques qui se posent dans ce domaine. [Traduit par la Rédaction] Mots-clés : unité motrice, désuétude, locomotion, animal, humain. Experimental approaches used to study MN properties and MU functionSince the development of intracellular MN recordings by Sir John Eccles during the 1950s (Brock et al. 1952(Brock et al. , 1953Coombs et al.

Neuropathic pain as a predictor of neurological disorders regression in patients with spinal cord traumatic injury

“…Neuroplasticity -mechanism determining reorganization of neuronal chains, e.g. during the motor training after the central nervous system injuries of either cortical or spinal level [14][15][16]. This type includes the functional improvements beyond the frameworks of neurological deficiency recovery, e.g.…”

Effects of Physiotherapy Interventions on the Function of the Locomotor System in Elder Age: View of Theory and Practice

“…In human investigations, indirect approach has been used to get information about the motor neuron behavior analyzing the response of the motor unit by using surface or intramuscular electromyography. The heterogenous training protocols make difficult to explore and interpret the association between the exercise features and the motor neuron response, so this field is open for further investigations [50].…”

Exercise-induced adaptation of neurons in the vertebrate locomotor system

“… 3 , 10 , 11 , 12 Extensive evidence has shown that chronic exercise leads to adaptive changes in the membrane properties and excitability of spinal motoneurons in rodents. 3 , 13 , 14 Indeed, recent studies of mouse spinal cord and midbrain neurons have found that chronic exercise induces morphological plasticity and alters their ion channel activity. 12 , 15 , 16 To fully grasp these recent observations and the underlying mechanisms of motor plasticity they are pointing to, a succinct summary of the previous research would be of great utility.…”