Before revision:  Analyzing multi-channel EEG from 18 healthy volunteers and 18 epileptic patients (all in their seize-free intervals), the derived relative entropy of symmetrical ordinal patterns shows advantages to other time irreversible parameters and significantly distinguish two kinds of brain electric signals (the epileptic have lower temporal asymmetries than the healthy) .
After revision:  Two chaotic models, the logistic and Henon systems, and reversible Gaussian process and their surrogate data are used to validate the time-irreversible measure, and time irreversibility of epileptic EEGs from Nanjing General Hospital is detected by the parameter .