(A) EEG changes after acute administration of ketamine-xylazine (KX). KX treatment (100mg/kg, 5mg/kg, i.p.) produced an EEG pattern dominated by slow waves compared with the EEG of saline injected controls recorded at the same time of day. Controls predominantly showed low amplitude, high frequency wake EEG. (B) Average EEG power spectra in KX and saline treated control rats (n = 6). Note the KX-induced high values of spectral power in the δ-frequency range, predominantly between 1.5 and 3.0 Hz. (C) KX treated animals showed a significant increase in total EEG δ-activity (n = 7, P = 0.002) when compared to saline treated controls.