Fig. 2. Time series representation of normalized performance during the testing phase for three stimulus pairs and three drug conditions. Plotted are normalized performance (see Materials and Methods) for each daily training session averaged across animals (mean ± SD) for the Long stimulus pair (  A ), Med stimulus pair (  B ), and Short stimulus pair (  C ) in the absence of isoflurane (  black squares ), in 0.2% isoflurane (  red circles ) and in 0.4% isoflurane (  green triangles ).