Unprocessed EEG traces and spectrograms from one animal. Top panels: On the left EEG traces (30 s duration) for each period and recording site (cortex in black, thalamus in blue). On the right is an expanded view of a 3 s segment. For better visibility the vertical scale is adjusted to ensure that each segment occupies the entire plotting area and the number to the left of each EEG segment indicates the scale of the vertical bar in µV. Middle panels – cortex: On the left is shown the spectrogram for the 30 s EEG segment recorded from the cortex for each concentration. Y axis: frequency; X axis: time; colour scale: power (dB). The decrease in high-frequency power is revealed by the predominance of the blue colour for the higher concentrations of dexmedetomidine. On the right, line plots showing the average value in dB for each frequency band and period. The grey rectangle shows the spectrogram data corresponding to the 30–50 Hz band during baseline and the average of these data (∼ 33 dB) is shown by the dot circled in grey. The line plots show that power decreased with increasing concentrations. Bottom panels – thalamus: Same as middle panels but for thalamic recordings.