RESUMO
Excellent models have been described in literatures which related membrane potential to extracellular electric or magnetic stimulation and which described the formation and propagation of action potentials along the axon, for both myelinated and nonmyelinated fibers. There is not, however, an adequate model for nerve injury which allows to compute the distribution of injury potential, a direct current potential difference between intact and injured nerve, because its importance has been ignored in the shadow of the well-known action potential. This paper focus on the injury potential and presents a model of the electrical properties of myelinated nerve which describes the time course of events following injury. The time-varying current and potential at all nodes can be computed from the model, and the factors relate to the amplitude of injury potential can be determined. It is shown that the amplitude of injury potential decreased gradually with injury time, and the recession curve was exponential. Results also showed that the initial amplitude of injury potential is positively related to the grade of injury and fiber diameter. This model explained the mechanism of formation of injury potential and can provide instruction for applied electric field to prevent the formation injury potential.
Assuntos
Modelos Neurológicos , Fibras Nervosas Mielinizadas/fisiologia , Animais , Axônios/fisiologia , Potenciais da Membrana/fisiologia , Bainha de Mielina/metabolismo , Traumatismos da Medula Espinal/fisiopatologiaRESUMO
Transcranial magnetic stimulation (TMS) is a non-invasive diagnostic and therapeutic technigue. This paper expounds the design and manufacture of the TMS system, which meets all the requirements of the TMS study and clinical diagnosis and treatments.
