听觉事件相关电位(ERPs)早期和晚期成份的任务负荷效应

目的 比较不同任务负荷的听觉事件相关电位（ERPs,event-related potentials)，以探讨听觉ERPs各种成份的任务负荷效应。方法 被试者为12名右利手正常在校大学生（20－23岁）。要求被试者对4个方位的声音信号进行难度负荷不同的3种作业任务：全反应（AR）、方位区分反应（DR）、音调选择方位式区分反应（SR）。对－t和方差分析统计3种任务的听觉ERPs成份。结果1）SR反应时最长，DR次之，AR最短；2）早期成份的任务负荷效应：P1波幅随负荷的增加进行性增强；AR－ERPs的NI峰值相近，均高于SR（T）－ERPs；DR－ERPs与SR（T）－ERPs中前脑区的P2波幅无明显差异，均显著低于AR－ERPs，P2的潜伏期随负荷的增加明显缩短；3）晚期成分的任务负荷效应；随任务负荷的增加，N2（N2a/N2b),P3和SW波幅明显增强。结论 听觉ERPs早期成份和晚期成份均有明显的任务负荷效应，晚期成份的任务负荷效应可能与早期的警觉激活程度相关联。

Effects of Task Load on Early and Late Components of Auditory Event-related Brain Potentials

Objective: To study the effects of task load on early and late components of auditory event-related potentials. Method: The subjects were 12 healthy right-handed volunteers aged 20-23 years. The stimuli were auditory signals of two kinds of tones and appeared randomly from four speakers located on the left-front, left-rear, right-front and right-rear over the head of the subject. Tasks included: a) pressing the button in response to all signals (AR); b) making location discrimination to tones from left or right (DR); c) making location discrimination to target signals (T, high-tone or low-tone) from the four sides, and make no response to non-target signals (NT). The event-related potentials (ERPs) of three tasks were compared with each other. Result: 1) The early components include P1, N1 and P2, and the late components include N2 (N2a/N2b), P3 and SW (slow wave). 2) P1 wave amplitude increased with the increase of the task load. N1 wave amplitude of SR(T)-ERPs decreased markedly compared with that of AR-ERPs and DR-ERPs, and P2 wave amplitude of AR-ERPs increased significantly compared with that of DR-ERPs and SR(T)-ERPs. P2 wave latency shortened with increase of the task load. 3) N2 (N2a/N2b), P3 and SW wave amplitudes increased with the increase of the task load. Conclusion: These data indicate that not only the late components but also the early components of auditory event-related potentials were affected by task load. The effects on the late components may be related to the change of the early component (P1) which may reflect the early activity process of the brain.