Résumé
ABSTRACT This paper reviews aspects of the life and work of Professor Louis Ranvier 140 years after the publication of Leçons sur l'histologie du système nerveux, published in 1878, and shows the importance of the histological description of myelinated fibers of the nodes of Ranvier.
RESUMO Os autores apresentam uma revisão sobre aspectos da vida e obra do Professor Louis Ranvier 140 anos após a publicação de seu livro Leçons sur l'histologie du système nerveux publicado em 1878 e mostra a importância da descrição histológica nas fibras mielínicas dos nodos de Ranvier.
Sujets)
Histoire du 19ème siècle , Histoire du 20ème siècle , Noeuds de Ranvier , Système nerveux/anatomie et histologie , Neurologie/histoire , Paris , Neurofibres myéliniséesRésumé
The classical cable function has been used to represent the response of peripheral nerves stimulated by external parallel electric field. It can not describe the excitation of peripheral nerves stimulated by perpendicular electric field. In this paper, responses of the nodes of Ranvier to transverse-field are deeply investigated by mathematic simulation and in-vitro experiments. The paper demonstrates that, under perpendicular electric field stimulation, the responses evoke a two-stage process including an initial polarization and the actual change of the transmembrane potential. It is the net inward current along a radial direction of the node of Ranvier that causes the peripheral nerve excitation. Based on the two-stage process, a novel model is introduced to describe peripheral nerves stimulated by transverse-field, and the classical cable function is modified. The new model and the improved cable function are verified by several in-vitro experiments. They can be used to represent peripheral nerves responses by arbitrary electric field stimulation.
Sujets)
Animaux , Bufo bufo , Conductivité électrique , Stimulation électrique , Champs électromagnétiques , Électrophysiologie , Potentiels de membrane , Modèles biologiques , Neurofibres , Physiologie , Nerfs périphériques , Physiologie , Noeuds de Ranvier , Physiologie , Nerf ischiatique , PhysiologieRésumé
Se describe la citología axonal y la ultraestructura de las aperturas mielínicas (nudos de Ranvier) de las fibras mielinizadas no gigantes del camarón Penaeus, comparándolas con las características morfológicas de otros nudos de Ranvier en invertebrados y vertebrados