We next determined the dose-dependent effects of ethanol vapor on sedation sensitivity and tolerance using a loss-of-righting assay (Fig. 1G to I). Flies showed sigmoidal sedation kinetics when exposed to a continuous stream of the moderate 60% ethanol vapor, with a time to 50% sedation of 25.6 ± 2.2 minutes (Fig. 1G). Because measuring the time to 50% sedation is labor intensive, we counted the number of flies sedated at 26 minutes (Sed) for subsequent analyses. Consistent with previous findings, naive flies showed increased sedation with increased ethanol concentration (Fig. 1H; Urizar et al., 2007). Flies developed robust tolerance to the sedating effects of ethanol (Sed Tol) that increased with increasing dose (Fig. 1I). In sum, these dose–response experiments revealed a correlation of 2 measures of behavioral plasticity in the rapid tolerance paradigm, ΔDist and Sed Tol, with both measures increasing with increasing ethanol concentration. Additionally, a low concentration of ethanol vapor (47%) revealed a potentiation of locomotor activity during hyperactivity onset of exposure 2 that may reflect sensitization to the locomotor activating effects of ethanol. These dose–response experiments defined
