Smoking cues impair monitoring but not stopping during response inhibition in abstinent male smokers

The attenuated inhibitory control of smokers is a stumbling block for treating nicotine dependence. Unfortunately, smokers are often exposed to cigarette-related salient cues, which may violate homeostasis, override self-control, and lead to relapse. To understand the mechanisms underlying these associations, we investigate the cognitive and neural processes of inhibitory control (including proactive and reactive inhibition) of smoking cues in abstinent smokers. Twenty-six smokers completed cue-reactivity and stop signal tasks during functional magnetic resonance imaging scans, on two separate sessions, 2-3 weeks apart: one involved a neutral cue reactivity task, and the other a smoking cue reactivity task. Findings pointed to no significant subjective craving changes, or behavioral influences of smoking cues on proactive and reactive inhibition. However, abstinent smokers exhibited hyperactive brain reactivity in response to smoking versus neutral stimuli, in regions including the insula, amygdala, anterior cingulate cortex (ACC), and putamen. They also had hypoactive bilateral rostral ACC (rACC) and hyperactive right pre-supplementary motor area during reactive inhibition in smoking versus neutral conditions. Support vector regression analysis showed that activation of these regions predicted and correlated with reactive inhibition index (i.e., SSRT), alluding to the possibility of their involvement in the reactive inhibition. Subjective craving scores were predicted by and correlated with activation of bilateral dorsal and rostral ACC, supporting the ideas of their possible involvement in subjective craving. These findings suggest that smoking cues evoke hyperactive brain reactivity; this may interfere with normal performance monitoring and rapid reactive inhibition. These findings have important implication for treating smoking dependence.