The effect of enhancing cholinergic neurotransmission by nicotine on EEG indices of inhibition in the human brain

The role of the cholinergic system in inhibition remains to be elucidated. Nicotine is a potent tool to augment this system, but most studies investigated its effects solely on behavior. Reference to brain activity is important to specifically identify inhibition-related mechanisms. In the current study the objective was to elucidate the role of the cholinergic system in inhibition. 16 healthy non-smokers performed in a stop task while EEG was recorded. A pre- versus post-treatment, within subjects, placebo controlled, single-blind design was used. It was hypothesized that nicotine would decrease stop-signal reaction time (SSRT) and increase the amplitude of inhibition-related event related potentials, the stop N2 and stop P3. Behavioral measures show nicotine shortened SSRT, but only when pretreatment values were not taken into account. On EEG measures, an enhanced stop P3 under nicotine was found, but only in a subsample sensitive to nicotine based on diastolic blood pressure. The results are indicative of enhanced inhibitory activity possibly reflecting enhanced activation in the superior frontal gyrus.