1. Attenuation of high-frequency (30–200 Hz) thalamocortical EEG rhythms as correlate of anaesthetic action: evidence from dexmedetomidine 
G. Plourde, F. Arseneau 
British Journal of Anaesthesia 
Volume 119, Issue 6, Pages (December 2017)
DOI: /bja/aex329
Copyright © 2017 The Author(s) Terms and Conditions

2. Fig 1
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.
British Journal of Anaesthesia  , DOI: ( /bja/aex329)
Copyright © 2017 The Author(s) Terms and Conditions

3. Fig 2
Changes in EEG power spectra during dexmedetomidine anaesthesia. The top panels show average power spectra for the group of 10 animals for cortex and thalamus. Bars show standard error. The blanks at 60, 120 and 180 Hz represent data excluded from analysis to minimize interference from external electrical sources. Note the log-log scales. Bottom panels show power spectra obtained from one animal for cortex and thalamus. Recovery data not shown to avoid distracting overlap. Abbreviations: base: baseline.
British Journal of Anaesthesia  , DOI: ( /bja/aex329)
Copyright © 2017 The Author(s) Terms and Conditions

4. Fig 3
EEG power as a function of dexmedetomidine concentration for each frequency band for cortex and thalamus. Thin lines represent data from each animal. The thick blue line shows the mean. The dashed red line shows the regression fit. Data from the recovery period were not included in the regression. The significance of the regression model was P<0.05 in all instances. See Table 1 for exact P values and regression parameter estimates.
British Journal of Anaesthesia  , DOI: ( /bja/aex329)
Copyright © 2017 The Author(s) Terms and Conditions

5. Fig 4
Normalized regression slopes for dexmedetomidine, propofol and isoflurane for cortex and thalamus (mean  std err). The P values (adjusted for multiple comparisons) indicate the significance of the slope differences between isoflurane or propofol and dexmedetomidine for each frequency band. For the cortex the slope for dexmedetomidine is significantly less steep than that of isoflurane for the 76–125 Hz and 126–200 Hz bands. For the thalamus, the slope for dexmedetomidine is significantly less steep than that of propofol and isoflurane for all frequency bands except 30–50 Hz.
British Journal of Anaesthesia  , DOI: ( /bja/aex329)
Copyright © 2017 The Author(s) Terms and Conditions

6. Fig 5
Thalamocortical coherence. The left column shows the average coherence with 95% confidence interval for the group of 10 animals for each frequency band during baseline. The right column shows the average coherence for the same frequency bands and for each period. The grey rectangle show the delta (0.3–4.0 Hz) band where coherence was increased at the two highest dexmedetomidine concentrations, when the animals were unconscious. The blanks at 60, 120 and 180 Hz represent data excluded from analysis to minimize interference from external electrical sources. The bar graph on the right shows the mean and standard error of delta coherence measures obtained from each animal. The grey bars correspond to periods when the animals were unconscious and show a modest, but highly significant, increase in coherence compared with the black bars that correspond to periods when consciousness was present.
British Journal of Anaesthesia  , DOI: ( /bja/aex329)
Copyright © 2017 The Author(s) Terms and Conditions