Detecting brain activity variation of rat during anesthesia by spectral entropy.

In order to detect and measure the brain activity variation under different depth of anesthesia (DOA), the Spectral Entropy (SE) of electroencephalogram (EEG) of the SD rat was studied in this paper. The SE of EEG was measured under different DOA and the relationship between SE and the DOA was analyzed. The SE of EEG will decrease quickly while the DOA is from light to deep and vice versa, so it can be used to distinguish light and deep anesthesia, but it can not distinguish awake and light anesthesia accurately. Compared with power spectrum, we can see the change of SE is opposite to that of power spectrum. Besides EEG SE analysis, the SE variations of four rhythms of EEG (delta, theta, alpha and beta) also are analyzed. The study shows SE of delta rhythm dynamic change leads to the change of EEG and the delta rhythm is the dominant rhythm of rat during anesthesia.