was mixed with a humidified air stream to achieve a flow rate of 5.5 l/min. Ethanol concentration is expressed as the percentage of ethanol vapor: [(ethanol vapor)/(ethanol vapor + humidified air)] × 100. Behavioral experiments were performed in the 8 chambered booz-o-mat, and locomotor tracking analysis was carried out as described previously (Wolf et al., 2002). Briefly, flies were allowed to acclimate to the testing chamber for 9 minutes in a stream of humidified air and were then switched to a stream of ethanol vapor. Fly locomotion was filmed starting 2 minutes before ethanol vapor application. Locomotor activity was quantified as the population average distance traveled over time over 20-second intervals at specific time-points using an automated locomotor tracking device. To induce rapid ethanol tolerance, flies were exposed to ethanol vapor for 26 minutes, and were allowed to rest for 3 to 3.5 hours before receiving a second ethanol exposure of the same length and concentration. Distance traveled (Dist) is defined as the area under the curve from 2 to 25 minutes as determined by trapezoidal summation, and ΔDist is Distexposure2 – Distexposure1. Peak speed (PS) is the greatest speed achieved from 2 to 25 minutes. Sedation sensitivity (Sed) was
