other factors that contribute substantial variability to results, such as the expectation to smoke at the end of the study54. Indeed, as discussed above13, expectation alone may mimic the effects of acute drug intake on PFC activation in addicted individuals. Studies in which all three variables — expectation for drug administration, exposure to drug-related cues and abstinence — are explored for main effects and interaction effects on PFC activity would be useful, particularly if they involve large samples. The temporal dynamics of PFC cue reactivity also remain to be explored in longitudinal studies, tracking the same individual throughout longer-term abstinence periods.
