Effect of Cigarette Smoking on Prefrontal Cortical Function in Nondeprived Smokers Performing the Stroop Task

Abstract

Some reports indicate that cigarette smoking can help smokers focus attention, even when they have not abstained from smoking for a substantial period of time (eg, 41 h). Understanding the mechanisms by which smoking affects attention may help in designing smoking cessation treatments. Thirteen nonsmokers and nine smokers participated in two tests of blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). During fMRI, the participants performed the Stroop Task. There was a 15-min break between the two tests. During the break, each smoker smoked one cigarette. For smokers, the first test began 45-60 min after the last cigarette of ad libitum smoking. The differences in BOLD signal changes between Stroop conditions (ie, incongruent minus congruent) showed a group  test interaction in the right precentral sulcus, including the putative human frontal eye field (FEF). Smokers, but not nonsmokers, showed greater changes (relative to rest) in BOLD signal in the incongruent than in the congruent condition in the first fMRI test but not in the second. Even after brief abstinence from smoking, therefore, smokers exhibit compromised functional efficiency in the right FEF and adjacent precentral sulcus in a test of selective attention; and smoking ameliorates this condition.

Chronic smoking and the BOLD response to a visual activation task and a breath hold task in patients with schizophrenia and healthy controls

“…If it is shown that heavy smokers have an increased capillary density in the brain, this finding might indeed have important implications for fMRI in smokers --the intrinsic signal in the blood is more than an order of magnitude larger than the extravascular signal (Buxton, 2002). Xu et al (2007) also reported an signal increase in abstinent smokers compared to non-smokers. Subjects performed the Stroop, a classic cognitive interference task.…”

“…They further hypothesize that their results reflect the fact that the inhibitory function of the right FEF may be compromised in abstinent smokers. Thus, Xu et al (2007) explain their results in terms of cognitive differences in smokers. There is evidence for reduced cognitive performance in chronic smokers [see Durazzo and Meyerhoff, (2007) for review], and certainly such effects could account for fMRI differences, including the increased BOLD percent signal change noted in the present study.…”

“…The signal increase was noted in the frontal eye fields resulting from the contrast between the incongruent stimuli minus the congruent stimuli. Xu et al (2007) suggest that this brain area is critically involved in attention. They further hypothesize that their results reflect the fact that the inhibitory function of the right FEF may be compromised in abstinent smokers.…”

“…They found that smokers had a reduced response in the parietal cortex and caudate. On the other hand, Xu et al (2007) found that smokers had a significantly elevated response to the Stroop task in the right precentral sulcus. We are not aware of any study which has compared heavy smoking and non-smoking groups on BOLD fMRI responses to a simple sensory activation task.…”

“…Two studies have compared non-smokers to smokers on cognitive tasks (Lawrence et al, 2002;Xu et al, 2007). Lawrence et al (2002) compared smokers to non-smokers on brain activation to a visual vigilance task.…”