Another five rats in each group underwent surgery 1 week prior to any PSD subjection or JTW intake, using standard procedures as bellow [
25]. Under pentobarbital (50 mg/kg, intraperitoneal injection)-induced anesthesia, two stainless steel screws (2 mm long, 1.2 mm of diameter) attached to insulated wire were implanted in the skull over the frontal-parietal cortex for electroencephalographic (EEG) recordings. One of the electrodes was placed approximately 2 mm anterior and 5 mm to the right of bregma; another was placed approximately 2 mm anterior and 5 mm to the left of bregma. Both of the electrodes were attached to a miniature connector. All connectors were cemented in place with dental acrylic. Right after the surgical implantation, the rats were injected with Penicillin sodium (80,000 unit dose for each rat) for 2 days and allowed to recover for 7 days prior to the initiation of the experiments. At the end of the 4th week, EEG recordings were collected. For the purpose of habituation, the animals were connected to the recording apparatus at least 1 day before the experiments for EEG recordings. The miniature connectors were connected to a RM-6280C 8-channel physiological signal recorder (Chengdu Instrument Factory, Chengdu, China) via the signal input lines. Make sure the animal can move freely within a wide range. The signals were amplified and filtered (1 ~ 30 Hz) digitized at a speed of 200 ms/disc, and recorded using Model RM6280C physiological signal acquisition and processing system. The system was run for EEG recording continuously for 4 h (10:00–14:00). The EEG waveform files were saved and the waves ratio tables were exported for further analysis. The power spectrum densities, integrated and averaged, could be divided into four frequency areas: δ wave (0.5 ~ 4 Hz), θ wave (4 ~ 8 Hz),αwave (8 ~ 14 Hz), and β wave (14 ~ 30 Hz). According to rat EEG, each epoch was assigned to one of the following categories [
26]: wakefulness (can be divided into two types of EEG: θ wave (4 ~ 8 Hz) when the rats in walking, climbing, exploring and focus behavior; irregular high-frequency and low-amplitude EEG activity when the rats licking the body and standing still), slow-wave sleep stage I (SWS
1, high-amplitude, low-frequency (1 ~ 5 Hz) and spindle waves (8 ~ 14 Hz) synchronous pattern activity, and high-amplitude and low-frequency wave ratio less than 50% share in each of the statistical unit (30 s), eyes closed, usually lying on the animal’s side or curled up with head down), slow-wave sleep stage II (SWS
2, same as SWS
1, but high-amplitude and low-frequency wave ratio more than 50% share in each of the statistical unit), REM sleep (low-frequency θ wave, with no significant difference between the waking state, occasional body twitches while maintaining a recumbent sleep posture. Since wakefulness could not directly turn to the REM sleep state, there was always the presence of SWS sleep before the REM sleep, and REM sleep could be directly convert into wakefulness or SWS sleep. REM sleeping time generally sustained not more than 3 min). Each individual sleeping phase lasted at least 20 s, and each analysis unit was 30 s. The total sleep time, total time of slow wave sleep (SWS
total), SWS
1 and SWS
2, and total time of REM sleep were calculated to analyze the differences among the four groups.