mM (Wolf et al., 2002). As ethanol continues to accumulate, the hyperactive phase is gradually terminated as locomotor incoordination and sedation increase (10 to 25 minutes in Fig. 1C, 6 to 25 minutes in Fig. 1D). Previous studies utilizing a rapid tolerance paradigm showed that 3.5 hours after being exposed to a moderately high ethanol vapor concentration (ethanol vapor mixed with humidified air to 60%), flies given a second exposure of the same concentration exhibited increased locomotor activity levels throughout the hyperactive phase (Scholz et al., 2000). This effect is likely due in part to the development of tolerance to the sedative and locomotor-incoordinating effects of ethanol (Berger et al., 2004).
