Lim C L, Rennie C, Barry R J, Bahramali H, Lazzaro I, Manor B, Gordon E
Department of Neurology, Westmead Hospital, Australia.
Int J Psychophysiol. 1997 Feb;25(2):97-109. doi: 10.1016/s0167-8760(96)00713-1.
Overlapping phasic skin conductance responses (SCRs) obtained using short interstimulus interval (ISI) paradigms such as those employed in cognitive research, confound measurement of each discrete phasic SCR as well as the tonic skin conductance level (SCL). We report a method of resolving this problem using a modelling technique that takes advantage of the stereotyped nature of the within-subject SCR waveform. A four-parameter sigmoid-exponential SCR model that describes the entire response, was developed and extended to five-, six- and eight-parameter skin conductance (SC) models. These SC models were successfully curve-fitted to more than 60 SC segments, each containing one SCR or two overlapping SCRs on a sloping baseline obtained from 20 normal subjects. The SC segments were consequently decomposed into their components: the tail of the previous response, one or two SCRs and the SCL. The SCRs free of the complication of overlap were then quantified. The raw SCRs of the same data set were also measured using a standard method. The standard measurement showed a significant reduction of 15% in amplitude and 140 ms in peak latency compared to our method. The basic four SCR model parameters--onset time, rise time, decay time constant and gain--showed increasing inter-subject variability in that order. These SCR model parameters may be studied as variables in normal and patient groups and as indices of treatment response. This quantitative method also provides a means to assess the relationships between central and autonomic psychophysiologic measures.
使用认知研究中采用的短刺激间隔（ISI）范式获得的重叠相位皮肤电导率反应（SCR），会混淆每个离散相位SCR以及皮肤电导率静息水平（SCL）的测量。我们报告了一种利用建模技术解决此问题的方法，该技术利用了受试者内部SCR波形的刻板性质。开发了一个描述整个反应的四参数S形指数SCR模型，并将其扩展为五参数、六参数和八参数皮肤电导率（SC）模型。这些SC模型成功地对60多个SC片段进行了曲线拟合，每个片段在从20名正常受试者获得的倾斜基线上包含一个SCR或两个重叠的SCR。因此，SC片段被分解为其组成部分：前一个反应的尾部、一个或两个SCR以及SCL。然后对没有重叠复杂性的SCR进行量化。同一数据集的原始SCR也使用标准方法进行测量。与我们的方法相比，标准测量显示幅度显著降低了15%，峰值潜伏期缩短了140毫秒。基本的四个SCR模型参数——起始时间、上升时间、衰减时间常数和增益——按此顺序显示出受试者间变异性增加。这些SCR模型参数可作为正常组和患者组的变量以及治疗反应指标进行研究。这种定量方法还提供了一种评估中枢和自主心理生理测量之间关系的手段。
