Figure 2. Incubation of nicotine craving in adolescent and adult rats is associated with increased neuronal activity in mPFC, OFC, NAc, and amygdala. Data are mean ± SEM numbers of Fos-IR neurons in dorsal and ventral mPFC (A, B), OFC (C), NAc core and shell (D, E), and central and basolateral amygdala (F, G) of adolescent and adult rats exposed to the extinction tests on withdrawal days 1 or 14. Left, Mean ± SEM Fos-labeled neurons. Center, Representative photomicrographs of Fos expression from the different groups (scale bar, 100 μm). Right, Sampling regions. *Different from day 1 within each age group, p < 0.05. n = 10–13 per group. SA, Self-administation.