Maurice D, Cerf R, Toussaint M
FORENAP, Institute for Research in Neurosciences, Neuropharmacology and Psychiatry, Centre Hospitalier, 27 rue du 4eme RSM, 68250 Rouffach, France.
Comput Methods Programs Biomed. 2002 May;68(2):93-108. doi: 10.1016/s0169-2607(01)00163-8.
This paper addresses the practical problems raised by the fact that correlation integrals computed from electroencephalographic signals do not scale. An automated procedure is described for alpha-waves, which is based on the known method of determining the correlation dimension from scaled structures that appear in diagrams of slope-curves. Automation, which is achieved using a moving window that detects the minima of slope-curves, and the density of minima makes it possible to vary the numerous parameters, and to implement tests. The potentialities of the automatic procedure are illustrated by results of psychopharmacological interest, based on the analysis of 22x10(3) alpha-signals, and the computation of 32x10(6) correlation integrals. Previous results concerning the existence of low-dimensional alpha-episodes, lasting in general not more than 5-6 s, are confirmed. Opposing effects upon the correlation dimension are described, at their pharmacological peak, for a dopaminergic agonist (apomorphine) and an atypical antipsychotic, a sigma-receptor ligand. The results also confirm that time reparametrization is a vital check in searches of low-dimensional attractor-ruled dynamics, and they suggest that subjects exhibiting 'high-alpha', i.e. whose alpha-waves are of amplitude A>30 microV, be selected for such investigations.
本文探讨了由脑电图信号计算出的关联积分不具有标度性这一事实所引发的实际问题。描述了一种针对阿尔法波的自动化程序，该程序基于从斜率曲线图表中出现的标度结构确定关联维数的已知方法。通过使用检测斜率曲线最小值的移动窗口实现自动化，最小值的密度使得可以改变众多参数并进行测试。基于对22×10³个阿尔法信号的分析以及32×10⁶个关联积分的计算，心理药理学相关结果展示了该自动程序的潜力。先前关于低维阿尔法片段的存在（通常持续不超过5 - 6秒）的结果得到了证实。描述了在药理学峰值时，多巴胺能激动剂（阿扑吗啡）和非典型抗精神病药物（一种西格玛受体配体）对关联维数的相反作用。结果还证实，时间重新参数化是搜索低维吸引子主导动力学时的一项重要检查，并且表明应选择表现出“高阿尔法”（即阿尔法波幅度A>30微伏）的受试者进行此类研究。
