Chaos analysis of EEG during isoflurane-induced loss of righting in rats.
Chaos analysis of EEG during isoflurane-induced loss of righting in rats.
复制标题
DOI：
10.3389/fnsys.2014.00203
复制
发表时间：
2014
影响因子：
3
通讯作者：
Bland BH
中科院分区：
文献类型：
--
作者：
MacIver MB;Bland BH
众所周知，脑电信号会产生混沌奇异吸引子，而这些吸引子的形状与麻醉深度有关。我们对植入的微电极(分别为第4层和CA1层)的额叶皮质和海马区微脑电信号进行了混沌分析。用异氟醚诱导大鼠翻正反射丧失(LORR)，并比较行为指标与吸引器形状的关系。LORR的静息脑电信号与清醒信号明显不同，更类似于慢波睡眠信号，在原始记录(高幅度慢波)和快速傅立叶变换分析(FFT；增加的增量功率)中很容易被识别，这与以前的研究很好地一致。通过使大鼠侧翻来测试翻正，刺激的脑电活动产生的信号与清醒的休息状态的脑电信号非常相似。也就是说，高幅慢波活动转变为持续数秒的低幅快活动，然后恢复到慢波活动。无论老鼠是否能够自我矫正，这种情况都会发生。测试爪子夹和尾夹反应产生类似的脑电激活，即使是在爆发抑制占主导地位的自发脑电的深度麻醉下也是如此。在失去反应的情况下，混沌吸引子形状在辨别这些类似清醒的信号方面比FFT分析要好得多。比较了清醒行走、慢波睡眠和异氟醚在不同麻醉深度下的脑电混沌分析和FFT分析。吸引器很容易区分自然睡眠和异氟醚诱导的“三角洲”活动。混沌吸引子的形状在从清醒到Lorr的转变过程中逐渐变化，这表明这不是一个类似开/关的转变，而是一个沿大脑状态连续体的点。
It has long been known that electroencephalogram (EEG) signals generate chaotic strange attractors and the shape of these attractors correlate with depth of anesthesia. We applied chaos analysis to frontal cortical and hippocampal micro-EEG signals from implanted microelectrodes (layer 4 and CA1, respectively). Rats were taken to and from loss of righting reflex (LORR) with isoflurane and behavioral measures were compared to attractor shape. Resting EEG signals at LORR differed markedly from awake signals, more similar to slow wave sleep signals, and easily discerned in raw recordings (high amplitude slow waves), and in fast Fourier transform analysis (FFT; increased delta power), in good agreement with previous studies. EEG activation stimulated by turning rats on their side, to test righting, produced signals quite similar to awake resting state EEG signals. That is, the high amplitude slow wave activity changed to low amplitude fast activity that lasted for several seconds, before returning to slow wave activity. This occurred regardless of whether the rat was able to right itself, or not. Testing paw pinch and tail clamp responses produced similar EEG activations, even from deep anesthesia when burst suppression dominated the spontaneous EEG. Chaotic attractor shape was far better at discerning between these awake-like signals, at loss of responses, than was FFT analysis. Comparisons are provided between FFT and chaos analysis of EEG during awake walking, slow wave sleep, and isoflurane-induced effects at several depths of anesthesia. Attractors readily discriminated between natural sleep and isoflurane-induced “delta” activity. Chaotic attractor shapes changed gradually through the transition from awake to LORR, indicating that this was not an on/off like transition, but rather a point along a continuum of brain states.