Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
J Alzheimers Dis. 2010;20 Suppl 1:S71-84. doi: 10.3233/JAD-2010-1417.
Caffeine has been consumed since ancient times due to its beneficial effects on attention, psychomotor function, and memory. Caffeine exerts its action mainly through an antagonism of cerebral adenosine receptors, although there are important secondary effects on other neurotransmitter systems. Recently, functional MRI (fMRI) entered the field of neuropharmacology to explore the intracerebral sites and mechanisms of action of pharmacological agents. However, as caffeine possesses vasoconstrictive properties it may interfere with the mechanisms underlying the functional contrast in fMRI. Yet, only a limited number of studies dealt with the effect of caffeine on measures in fMRI. Even fewer neuroimaging studies examined the effects that caffeine exerts on cognition: Portas and colleagues used fMRI in an attentional task under different levels of arousal (sleep deprivation or caffeine administration), concluding that the thalamus is involved in mediating the interaction of attention and arousal. Bendlin and colleagues found caffeine to stabilize the extent of neuronal activation in repetitive word stem completion, counteracting the general task practice effect. Recently, Koppelstaetter and colleagues assessed the effect of caffeine on verbal working memory demonstrating a modulatory effect of caffeine on brain regions (medial frontopolar and anterior cingulate cortex) that have been associated with attentional and executive functions. This review surveys and discusses neuroimaging findings on 1) how caffeine affects the contrast underlying fMRI techniques, particularly the blood oxygen level dependent contrast (BOLD fMRI), and 2) how caffeine operates on neuronal activity underlying cognition, to understand the effect of caffeine on behavior and its neurobiological underpinnings.
咖啡因由于其在注意力、精神运动功能和记忆方面的有益作用，自古以来就被人们所消费。咖啡因主要通过拮抗大脑腺苷受体发挥作用，尽管它对其他神经递质系统也有重要的次要作用。最近，功能磁共振成像（fMRI）进入神经药理学领域，以探索药物在大脑内的作用部位和作用机制。然而，由于咖啡因具有血管收缩特性，它可能会干扰 fMRI 中功能性对比的机制。然而，只有少数研究涉及咖啡因对 fMRI 测量的影响。更少的神经影像学研究研究了咖啡因对认知的影响：Portas 及其同事在不同觉醒水平（睡眠剥夺或咖啡因给药）下使用 fMRI 进行注意任务，得出结论认为丘脑参与介导注意力和觉醒的相互作用。Bendlin 及其同事发现咖啡因可以稳定重复单词完成中的神经元激活程度，抵消一般任务练习效应。最近，Koppelstaetter 及其同事评估了咖啡因对言语工作记忆的影响，证明咖啡因对与注意力和执行功能相关的脑区（内侧额极和前扣带皮层）具有调节作用。这篇综述调查和讨论了 1）咖啡因如何影响 fMRI 技术的对比基础，特别是血氧水平依赖对比（BOLD fMRI），以及 2）咖啡因如何影响认知的神经元活动，以了解咖啡因对行为及其神经生物学基础的影响。
