Ernst M, Matochik J A, Heishman S J, Van Horn J D, Jons P H, Henningfield J E, London E D
Brain Imaging Center and Clinical Pharmacology and Therapeutics Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA.
Proc Natl Acad Sci U S A. 2001 Apr 10;98(8):4728-33. doi: 10.1073/pnas.061369098. Epub 2001 Mar 27.
Nicotine influences cognition and behavior, but the mechanisms by which these effects occur are unclear. By using positron emission tomography, we measured cognitive activation (increases in relative regional cerebral blood flow) during a working memory task [2-back task (2BT)] in 11 abstinent smokers and 11 ex-smokers. Assays were performed both after administration of placebo gum and 4-mg nicotine gum. Performance on the 2BT did not differ between groups in either condition, and the pattern of brain activation by the 2BT was consistent with reports in the literature. However, in the placebo condition, activation in ex-smokers predominated in the left hemisphere, whereas in smokers, it occurred in the right hemisphere. When nicotine was administered, activation was reduced in smokers but enhanced in ex-smokers. The lateralization of activation as a function of nicotine dependence suggests that chronic exposure to nicotine or withdrawal from nicotine affects cognitive strategies used to perform the memory task. Furthermore, the lack of enhancement of activation after nicotine administration in smokers likely reflects tolerance.
尼古丁会影响认知和行为，但其产生这些影响的机制尚不清楚。通过正电子发射断层扫描，我们在11名戒烟者和11名已戒烟者执行工作记忆任务（2-back任务，简称2BT）期间测量了认知激活（相对局部脑血流量增加）情况。在服用安慰剂口香糖和4毫克尼古丁口香糖后均进行了检测。在两种情况下，两组在2BT任务中的表现均无差异，并且2BT任务引起的大脑激活模式与文献报道一致。然而，在安慰剂条件下，已戒烟者的激活主要发生在左半球，而吸烟者的激活则发生在右半球。服用尼古丁后，吸烟者的激活减少，而已戒烟者的激活增强。激活的偏侧化作为尼古丁依赖的一种表现，表明长期接触尼古丁或戒除尼古丁会影响执行记忆任务时所使用的认知策略。此外，吸烟者在服用尼古丁后激活没有增强，这可能反映了耐受性。
