Fig. 1. Intrathalamic nicotine dose parameter study. The data are shown as the proportion of categorical behavioral responses caused by the intrathalamic microinfusion of nicotine at the various escalating doses. The doses of nicotine were microinfused in 0.5 μl saline vehicle over 1 min, and responses were monitored over the next 30 min. Full arousal is seen only with the 100- and 150-μg dose microinfusions, with the 150-μg dose showing a qualitatively higher rate of generating a full arousal response. The numbers above each bar represent the number of infusions given at each respective dose.