[The spinal cord evoked potential by computer simulation: elucidation of killed-end potentials and augmentation caused by the conduction block phenomenon].
Single nerve fiber action potential (single-NAP) was computer simulated using solid angle approximation theory. The simulated spinal cord evoked potential (Simulated-SCEP) was then produced by summing the simulated single-NAPs according to the data of the fiber diameter spectrum of the human spino-cerebellar tract. To model the conduction block phenomenon in the spinal cord, it was assumed that each fiber impulse which reached the conduction block point could not go through the point and gradually became smaller. When the largest 10% of the constituent fibers had become blocked, there was augmentation of the negative peak at just before the conduction block point and at every point after the block. As the percentage of the blocked fibers increased, the amplitude of the simulated-SCEP decreased at every point except at just before the block. When 50% or more of the largest fibers were blocked, then augmentation of the negative peak still remained at just before the conduction block. However at the points just after the conduction block there was a monophasic positive waveform which is known as the killed-end potential. Phase cancellation normally dictates the wave forms of compound action potential. However, the killed-end potential and the augmentation of the amplitude associated with the conduction block can be explained by the loss of the phase cancellation.
Ushida
T
T
Department of Orthopaedic Surgery, Kochi Medical School, Japan.
Tani
T
T
D000200:Action Potentials; D003198:Computer Simulation; D005071:Evoked Potentials; D006801:Humans; D009431:Neural Conduction / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*