Partial antagonism of propofol anaesthesia by physostigmine in rats is associated with potentiation of fast (80–200 Hz) oscillations in the thalamus  S.J. Reed, G. Plourde, S. Tobin, C.A. Chapman  British Journal of Anaesthesia  Volume 110, Issue 4, Pages 646-653 (April 2013) DOI: 10.1093/bja/aes432 Copyright © 2013 The Author(s) Terms and Conditions

Fig 1 Power in the 50–200 Hz range in the barrel cortex and ventroposteromedial thalamus for tests that used either the anticholinesterase physostigmine (left) and/or saline (right) injections during propofol anaesthesia. A thin line indicates data for each animal, and a thick line shows the median power. Power was calculated during the baseline period (base), propofol anaesthesia (propo), after injection of either physostigmine (physo) or saline, and after recovery (reco) from anaesthesia. P-values for pair-wise comparisons are also indicated (Wilcoxon matched pairs test; corrected for multiple comparisons). British Journal of Anaesthesia 2013 110, 646-653DOI: (10.1093/bja/aes432) Copyright © 2013 The Author(s) Terms and Conditions

Fig 2 Changes in behavioural arousal induced by injection of physostigmine during propofol anaesthesia are correlated with increases in gamma/high-gamma power in the ventroposteromedial thalamus. (a) A scattergram shows the relationship between changes in thalamic power over 50–200 Hz and the rank of the arousal response to physostigmine among the 10 animals tested. The best-fit linear regression is shown by dashed lines, and R indicates the Spearman rank order correlation coefficient. The points labelled #2 and #4 designate two animals that showed a high and low arousal response, respectively (Table 1) whose data are shown in (b) and (c). (b) The power spectra for animal #2 that showed a strong arousal response reveal an increase in gamma power after injection of physostigmine (filled arrow). The power spectra for animal #4 that showed a minimal arousal response indicate no increase in gamma power after physostigmine (open arrow). Cx, cortex; Th, thalamus. (c) Representative segments of LFPs obtained during the four stages of the recording sessions are shown for animals #2 and #4. The effect of physostigmine on the thalamic recording of animal #2 is readily visible (filled arrows), but changes in the traces of animal #4 were minimal (open arrows). British Journal of Anaesthesia 2013 110, 646-653DOI: (10.1093/bja/aes432) Copyright © 2013 The Author(s) Terms and Conditions

Fig 3 Average power spectra over the gamma/high-gamma range (50–200 Hz) for all animals combined for both sessions (physostigmine and saline) and recording sites (Cx, cortex; Th, thalamus). Mean (sem). sem shown for every 12th data point for clarity. The blank areas at 60, 120, and 180 Hz show the power ranges excluded from analysis to avoid contamination from power line noise. In comparison with baseline, gamma/high-gamma power decreased during anaesthesia. Thalamic gamma/high-gamma power increased after physostigmine and decreased after saline. Cortical gamma/high-gamma power also decreased after saline. British Journal of Anaesthesia 2013 110, 646-653DOI: (10.1093/bja/aes432) Copyright © 2013 The Author(s) Terms and Conditions