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.