Xu Jiansong, Mendrek Adrianna, Cohen Mark S, Monterosso John, Simon Sara, Brody Arthur L, Jarvik Murray, Rodriguez Paul, Ernst Monique, London Edythe D
Department of Psychiatry, University of California Los Angeles, Los Angeles, CA 90024, USA.
Psychiatry Res. 2006 Dec 1;148(2-3):103-9. doi: 10.1016/j.pscychresns.2006.09.005. Epub 2006 Nov 7.
We previously reported that compared with a non-deprivation state, overnight abstinence from cigarette smoking was associated with higher brain activity in the left dorsolateral prefrontal cortex (L-DLPFC) during a low demanding working memory challenge, and little increase beyond this activity level during more taxing working memory conditions. In the present study, we aimed to assess how recent smoking (overnight abstinence vs. smoking ad libitum) influenced the effect of smoking a cigarette on brain activity related to a working memory challenge. Six smokers performed the N-Back working memory task during functional magnetic resonance imaging (fMRI) both before and after smoking a cigarette in each of two test sessions: one following overnight abstinence from smoking ( approximately 13 h) and the other following ad libitum smoking. Task-related activity in L-DLPFC showed a significant interaction between the effects of acute smoking, test session, and task load. After overnight abstinence, post-smoking brain activity in L-DLPFC was lower than before smoking at low task load and higher at high task load; corresponding activity on a day of ad libitum smoking was higher at low load and lower at high task load after smoking during the session. These data suggest that the effect of acute smoking on working memory processing depends on recent prior smoking and task load. In particular, they provide preliminary evidence that functional efficiency of working memory is improved by smoking a cigarette during abstinence, while the effect of a cigarette in a non-deprived state varies with the nature and difficulty of the working memory challenge. This interaction merits further examination in larger studies specifically designed to consider this issue.
我们之前曾报道，与非剥夺状态相比，在低要求工作记忆挑战期间，夜间戒烟与左侧背外侧前额叶皮质（L-DLPFC）的脑活动增加有关，而在要求更高的工作记忆条件下，这种活动水平几乎没有进一步增加。在本研究中，我们旨在评估近期吸烟情况（夜间戒烟与随意吸烟）如何影响吸烟对与工作记忆挑战相关的脑活动的作用。六名吸烟者在两个测试环节中的每次吸烟前后，于功能磁共振成像（fMRI）期间执行N-回溯工作记忆任务：一个环节是在夜间戒烟（约13小时）后，另一个环节是在随意吸烟后。L-DLPFC中与任务相关的活动显示出急性吸烟、测试环节和任务负荷的影响之间存在显著交互作用。夜间戒烟后，低任务负荷下L-DLPFC的吸烟后脑活动低于吸烟前，高任务负荷下则高于吸烟前；在随意吸烟日，该环节吸烟后低负荷时相应活动较高，高任务负荷时较低。这些数据表明，急性吸烟对工作记忆处理的影响取决于近期的吸烟情况和任务负荷。特别是，它们提供了初步证据，即戒烟期间吸烟可提高工作记忆的功能效率，而在非剥夺状态下吸烟的效果则随工作记忆挑战的性质和难度而变化。这种交互作用值得在专门设计考虑此问题的更大规模研究中进一步研究。
