Hirano C, Russell A T, Ornitz E M, Liu M
Nagahama Red Cross Hospital, Japan.
Int J Psychophysiol. 1996 Apr-May;22(1-2):97-109. doi: 10.1016/0167-8760(96)00018-9.
Positive EEG deflections with the latency and scalp distribution of the P300 accompany startle in response to loud auditory stimuli in a non-task context. The purpose of this investigation is to determine if habituation would have effects on the P300 similar to those on the startle blink. Thirty-four normal 7 to 11-year-old boys from a startle habituation study had EEG recordings of sufficient quality to provide data for the current study. Startle was measured both as orbicularis oculi EMG and vertical EOG and P300 was recorded at Pz in response to 40,104 dB bursts of white noise presented at 23-s intervals. Both the startle response and the P300 habituated toward asymptotic levels after the first 28 trials, suggesting that both startle and the subsequent cognitive evaluation of the startling stimulus, reflected in the P300 response, are modulated by a common neurophysiological mechanism extrinsic to the direct startle pathway. A modest significant correlation between the P300 and the vertical EOG peak latencies for the initial trials suggests that the cognitive evaluation of the startling stimulus may also include evaluation of the reflex response to that stimulus. Analyses of the within-subject associations between startle and P300 initial amplitudes and rates of habituation showed that these parameters varied independently within the individual subject, suggesting that the P300 is not a component of the startle response. Rather, it reflects an evaluation of the startling stimulus, decreasing in amplitude as the surprising value of the startling stimulus decreases with habituation.
在非任务情境中，对大声听觉刺激的惊吓反应会伴随着潜伏期和头皮分布与P300一致的脑电图正向偏转。本研究的目的是确定习惯化是否会对P300产生与对惊吓眨眼相同的影响。来自一项惊吓习惯化研究的34名7至11岁正常男孩的脑电图记录质量足以为本研究提供数据。惊吓反应通过眼轮匝肌肌电图和垂直眼电图进行测量，P300则在头顶中央（Pz）记录，以响应每隔23秒呈现的40、104分贝的白噪声猝发。在前28次试验后，惊吓反应和P300都趋向于渐近水平，这表明惊吓以及P300反应中所反映的对惊吓刺激的后续认知评估，都受到直接惊吓通路之外的一种共同神经生理机制的调节。最初几次试验中，P300与垂直眼电图峰值潜伏期之间存在适度的显著相关性，这表明对惊吓刺激的认知评估可能还包括对该刺激的反射反应的评估。对惊吓和P300初始振幅以及习惯化速率之间的个体内关联分析表明，这些参数在个体受试者内部是独立变化的，这表明P300不是惊吓反应的一个组成部分。相反，它反映了对惊吓刺激的评估，随着惊吓刺激的惊奇值随着习惯化而降低，其振幅也会减小。
