Figure 2.

Total nicotine intake and latency to first press during nicotine SA sessions. A, Average nicotine intake (i.e., total number of infusions per session) during initial nicotine SA and reexposure is plotted as a function of SA training day (i.e., days 1–23 of initial SA and days 1–7 of reexposure, respectively). B, Average latency to first press is plotted as a function of recording day (i.e., Hab, habituation; SA3 and SA23, days 3 and 23 of initial SA stage; R1, R3, and R7, days 1, 3, and 7 of reexposure). The asterisk (*) denotes a significant difference (p < 0.05) relative to the 3rd and the 23rd days of initial SA. Error bars indicate SEM.