实验性颅内高压诱发家兔自发脑电非线性特征的变化

目的观察实验性高颅压条件下家兔自发脑电非线性特征的变化，探讨在重力变化引起颅内压改变，进而影响脑功能变化的研究中应用脑电复杂性指标的可能性。方法以家免为实验对象，以灌注法改变颅内压，应用关联维和李亚普诺夫指数等参数估计不同颅内压条件下脑电信号的复杂性特征。结果加压前正常颅内压条件下，动物的自发脑电信号均具有正的李亚普诺夫指数和分数关联维，提示这种信号具有混沌性质。实验性高颅压条件下，李亚普诺夫指数在每例动物都明显降低，提示脑电活动的复杂性降低。颅内压恢复正常值，李亚普诺夫指数的变化具有良好的可逆性，提示有限的高颅压引起的脑电活动的复杂度的变化是可逆的。结论自发脑电信号的李亚普诺夫指数作为监测颅内压变化时脑功能变化的指标，具有一定的应用价值。

Changes of nonlinear characters in rabbit EEG induced by experimental intracranial hypertension

bjective To observe the changes in the nonlinear characters of rabbit spontaneous EEG induced by experimental intracranial hypertension.The possibility of the application of the EEG complex index in the study of brain function is also evaluated. Methods Rabbit intracranial pressure was changed by CSF perfusion,EEG signals were recorded and their Lyapunov exponent(LE) and correlation dimension were calculated to obesrve the changes in the nonlinear characters. Results Under normal intracranial pressure (ICP), positive LE and fractal D2 were obtained,implying that normal rabbit EEG was chaotic.When ICP was experimently elevated,LE was decreased while D2 was not changed.The decrease of LE was reversible when the ICP was returned to normal level. Conclusions It is suggested that LE is an useful index for monitoring brain function during the change of ICP.