examining between-group differences for which there was a significant effect of group, four planned post hoc between-group comparisons were conducted, i.e., between 1 week abstinent smokers and 1 day, 2 week, 4 week, and 6-12 week abstinent smokers. For these post hoc tests, p-values were Bonferroni corrected for multiple comparisons, and statistical significance was considered at p≤0.00625. Correlational analyses for the associations between receptor availability and smoking assessments were conducted using SPSS version 16.0 (SPSS Inc. Headquarters, Chicago, IL). Correlations between β2*-nAChR availability, VT/fP, at each time point and clinical variables (smoking, craving, withdrawal) were assessed with Spearman's rho correlation coefficients. Different slopes for each abstinence time point were estimated to illustrate the relationship between significant clinical variables and β2*-nAChR availability. Due to multiple comparisons, statistical significance was considered at p≤0.01.
