1. Isoflurane impairs odour discrimination learning in rats: differential effects on short- and long-term memory 
R.A. Pearce, P. Duscher, K. Van Dyke, M. Lee, A.C. Andrei, M. Perouansky 
British Journal of Anaesthesia 
Volume 108, Issue 4, Pages (April 2012)
DOI: /bja/aer451
Copyright © 2012 The Author(s) Terms and Conditions

2. Fig 1
Experimental apparatus for olfactory learning, replicated from Eichenbaum and colleagues12 with an adaptation for inhalation anaesthesia. Task A (successive cue odour presentation) is illustrated in the upper panel: the animal had to maintain the nose poke for 2 s in order to receive the water reward (symbolized by drop) if the presented odour was the ‘positive’ one. Task B (simultaneous cue odour presentation) is shown in the lower panel. Two odours were presented simultaneously from two sources and the rat had to select and maintain a nose poke for the ‘positive’ odour in order to be rewarded.
British Journal of Anaesthesia  , DOI: ( /bja/aer451)
Copyright © 2012 The Author(s) Terms and Conditions

3. Fig 2
Experiment 2 (24 h recall) paradigm. The intrinsic preference of an individual for one odour out of a pair was determined initially (intrinsic preference, day 1, left). Subsequently, on the same day, the animals were trained under control conditions (0% isoflurane) or anaesthesia (0.3% or 0.4% isoflurane); the non-preferred odour was designated as having ‘positive valence’ and was the rewarded odour (acquisition of learning set, day 1, right). The following day, a ‘probe’ session was conducted consisting of 10 unrewarded trials using the odour pair from day 1 (day 2, left). If animals remembered the odour valences as established on day 1, we expected them to prefer the ‘positive’ odour. If they did not remember the odour valence, we expected them to show the same odour preference in the probe test on day 2 as during the intrinsic preference test of day 1. This ‘probe test’, which was used to assess their memory, was followed by a ‘rules reinforcement session’ that was not used to assess memory.
British Journal of Anaesthesia  , DOI: ( /bja/aer451)
Copyright © 2012 The Author(s) Terms and Conditions

4. Fig 3
Summary histograms of the observed (O) minus expected (E) number of nose pokes during the probe session. Positive O–E values support the existence of long-term memory. The smooth line is the best fit of a Gaussian function to the data. P-values (P) were obtained based on t-tests that assess the departure from zero (zero indicates no change in preference, so no long-term memory).
British Journal of Anaesthesia  , DOI: ( /bja/aer451)
Copyright © 2012 The Author(s) Terms and Conditions