脳誘発電位のベクトル的解析 : Simulationによる基礎的研究

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The purpose of the present report is to interpret human auditory evoked brain potentials recorded by the three-dimentional approach. Vectors of waves recorded by farfield technique were analysed. Simulation using a glass beaker and jelly was made on the assumption that physiological brain was a sphere of electrically homogeneous medium.On the inner surface of a beaker, six electrodes were attached so that lines drawn between confronting electrodes formed three axis, X, Y and Z, which met at right angles with each in the middle of the beaker. Two resistance wires were positioned on X and Y axis respectively in the center of the structure. The beaker was filled with jelly dissolved in copper sulfate solution. Each electrode was connected to the wires by the jelly which was electrically homogenous but resistant medium.This system implied that the resistance wires simulated the nervous pathway and the jelly tissues around it.When a pulsed current was transmitted in the resistance wires, the electrical activity was recorded from the electrodes of three axis.We studied the wave forms of three planes and then analysed their vectors on the basis of Lissajous figure. The vector pointed to the direction of current flow. When one resistance wire was loaded, the waves recorded by the electrodes of three axis were all the same with regard to amplitude and phase. However, they were different when a pulsed current was conducted in two resistance wires at the same time. Yet, the electrical vectors of resistance were identical to the directions of Lissajous figures of waves on three planes; frontal, horizontal and sagittal.An experiment was performed also in a dog. Three electrodes were inserted into the brain with the aid of X-ray study, and a pulsed current was transmitted. The electrical activity was induced by surface electrodes placed on the head of the dog. Lissajous figures of three waves had the same direction as the current flow of the intracerebral electrodes had.It is reasonable to suppose that physiological brain is electrically homogenous, because the present experiment by using a dog brain revealed the similar results as the simulation in the jelly.Therefore we examined auditory evoked brain potentials recorded on three axis in a healthy subject. Lissajous figures showed the following facts.N1 and N3 waves directed toward the opposite side to stimuli. Althogh the latter had a slight vertical component, they directed horizontaly. N5 waves was the largest vector toward a frontoparietal region. Vector of N2 and N4 waves were not completely confirmed. Thus, threedimentional analysis of evoked brain potentials will help us to understand thoroughly the nervous functions such as hearing.
社団法人日本耳鼻咽喉科学会の論文

脳誘発電位のベクトル的解析 : Simulationによる基礎的研究

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