Critical involvement of the thalamus and precuneus during restoration of consciousness with physostigmine in humans during propofol anaesthesia: a positron emission tomography study  G. Xie, A. Deschamps, S.B. Backman, P. Fiset, D. Chartrand, A. Dagher, G. Plourde  British Journal of Anaesthesia  Volume 106, Issue 4, Pages 548-557 (April 2011) DOI: 10.1093/bja/aeq415 Copyright © 2011 The Author(s) Terms and Conditions

Fig 1 Experimental plan for drug administration and data acquisition. (a) Two scans (15 min apart) were obtained for each period: awake baseline (B), anaesthesia (A), physostigmine (P), and recovery (R). After baseline recordings, the infusion of propofol was started and the target concentration was increased in small steps until unconsciousness occurred. Physostigmine was started after scan A2 as an initial bolus over 2 min followed by a continuous infusion. Scan P1 was started 2 min after the return of consciousness (or 10 min after the start of physostigmine if the subject failed to regain consciousness). Scan R1 was acquired about 20 min after the end of the propofol and physostigmine infusions. Subjects were expected to be conscious during all periods except anaesthesia. Infusion rates not drawn to scale. (b) Response to physostigmine and data acquisition. British Journal of Anaesthesia 2011 106, 548-557DOI: (10.1093/bja/aeq415) Copyright © 2011 The Author(s) Terms and Conditions

Fig 2 Propofol concentration in plasma and physiological measures (heart rate, mean arterial pressure, arterial partial pressure of CO2, and global CBF). Each line represents one subject. For simplicity, we only report significant differences between adjacent periods. The only statistical comparisons done for propofol were between anaesthesia and physostigmine for responders and non-responders (NS in both cases). a, P<0.05 for non-responders; b, P<0.01 for both groups; c, P<0.005 for both groups; d, P<0.005 for responders and P<0.05 for non-responders; e, P<0.01 for responders; f, P<0.01 for responders and P<0.05 for non-responders. British Journal of Anaesthesia 2011 106, 548-557DOI: (10.1093/bja/aeq415) Copyright © 2011 The Author(s) Terms and Conditions

Fig 3 Imaging data for the BASE–ANES and PHYSO–ANES contrasts in responders and non-responders. (a) Activation t-maps overlaid over average anatomical MRI in standard stereotaxic space. Colour scale shows the t-value. Stereotaxic coordinate of the section plane in yellow. The right side of the images corresponds to the right side of the subjects in this and all other figures. This contrast reveals the areas where rCBF was greater during baseline or physostigmine than during anaesthesia. For the BASE–ANES contrast, the areas are the precuneus and right thalamus. For the PHYSO–ANES contrast, the areas are the cuneus, precuneus, and thalamus. (b) The conjunction between the two activation t-maps shown in (a) for t>4.5 is shown in pink overlaid over average anatomical MRI. This analysis reveals voxels where the decrease in rCBF reached significance on the basis of t-values in both contrasts. The bar graphs (precuneus on the left; thalamus on the right) show rCBF [mean (sem)] for a spherical 4 mm region-of-interest centred at the middle of the conjunction areas [stereotaxic coordinates (x,y,z): 5, −17, 8 for the thalamus; 1, −67, 32 for the precuneus]. (c) Same as (a) for non-responders. The BASE–ANES contrast shows decreased rCBF in the precuneus and right thalamus during anaesthesia, as for responders. The PHYSO–ANES contrast show increased rCBF in the cuneus after physostigmine but no changes in the precuneus and in the thalamus. British Journal of Anaesthesia 2011 106, 548-557DOI: (10.1093/bja/aeq415) Copyright © 2011 The Author(s) Terms and Conditions