听觉P300电位及其亚成分偶极子分析

Auditory potential P300 and its dipole subcomponents

目的:确定听觉P300电位及其亚成分P3a和P3b波的起源。方法:用听觉Oddball范式从15名健康被试者头皮上的64导电极帽记录事件相关电位(event-relatedpotentials,ERPs),选取75%总场强(globalfieldpower,GFP)的时间范围作为计算偶极子的时间窗,偶极子分析采用逆算法原理。结果:30%被试者的P300分叉为P3a和P3b波。P300及其亚成分的潜伏期和波幅均具有主效应,P3a电位的潜伏期最短,波幅最小。P300电位的起源可用1～3个等价偶极子表示,P3a及未分叉P300的前半部分(240～310ms)的偶极子定位于扣带前回,P3b及未分叉P300的后半部分(310～420ms)定位于颞叶内侧附近,包括海马、海马旁回、杏仁核、扣带回及丘脑,未分叉的P300至少由相当于P3a和P3b的两部分组成,并且这两部分的偶极子与P3a和P3b的偶极子定位相似。结论:P300电位中的P3a亚成分及未分叉P300前半部分起源于于扣带前回,P3b亚成分及未分叉P300的后半部分起源于颞叶内侧,包括海马、海马旁回及丘脑等结构。

AIM:To identify the origin of auditory potential P300 and its subcomponents P3a and P3b. METHODS:Event related potentials(ERPs) from 15 normal subjects were recorded with 64 electrodes distributed over the scalp. The time range of 75%global field power (GFP) was selected to calculate the time window of dipole, which was analysed by inverse method. RESULTS:P300 potentials in 30%of subjects were bifurcated as P3a and P3b waves.The major effects existed in the incubation period and amplitude of P300 and its subcomponents, especially both of P3a was the shortest.The origin of P300 potential could be accounted by one to three equal dipoles. For the earlier parts(240 to 310 ms) of non bifurcated P300 and P3a of dipoles were located in anterior cingulate gyrus, and for the later parts(310 to 420 ms) of non bifurcated P300 and P3b of dipoles were located near medial temporal areas including hippocampal formations, hippocampal gyurs, amygdala, cingulated gyrus and thalamus. The non bifurcated P300 was considered as both P3a and P3b and its dipole was similar with the dipoles located in P3a and P3b. CONCLUSION: P3a subcomponents and the former parts of non bifurcated P300 in P300 potential come of anterior cingulate gyrus, and P3b subcomponents and the latter parts of non bifurcated P300 come of the medial temporal vicinal regions including hippocampal formations, hippocampal gyurs, thalamus, and so on.