Department of Psychology, Experimental Psychology, Ludwig Maximilian University, Munich, Germany.
Psychopharmacology (Berl). 2010 Jun;210(3):317-29. doi: 10.1007/s00213-010-1823-x. Epub 2010 Mar 30.
Theory of visual attention (TVA; Bundesen 1990) whole report tasks allow the independent measurement of visual perceptual processing speed and visual short-term memory (vSTM) storage capacity, unconfounded by motor speed. This study investigates how cognitive enhancing effects of psychostimulants depend on baseline performance and individual plasma levels.
Eighteen healthy volunteers (aged 20-35 years) received single oral doses of either 40 mg methylphenidate, 400 mg modafinil or placebo in a counterbalanced, double-blind crossover design. A whole report of visually presented letter arrays was performed 2.5-3.5 h after drug administration, and blood samples for plasma level analysis were taken.
Methylphenidate and modafinil both enhanced perceptual processing speed in participants with low baseline (placebo) performance. These improvements correlated with subjective alertness. Furthermore, we observed differential plasma level-dependent effects of methylphenidate in lower and higher performing participants: higher plasma levels led to a greater improvement in low-performing participants and to decreasing improvement in high-performing participants. Modafinil enhanced visual short-term memory storage capacity in low-performing participants.
This is the first pharmacological investigation demonstrating the usefulness of a TVA task for high-resolution and repeated cognitive parameter estimation after cognitive-enhancing medication. Our results confirm previous findings of attentional capacity improvements in low performers and extend the baseline dependency model to methylphenidate. Plasma level-dependent effects of psychostimulants can be modelled on an inverted U-shaped dose-response relationship, which is highly relevant to predict cognitive enhancing and detrimental effects of psychostimulants in patients with cognitive deficits (e.g., attention deficit hyperactivity disorder) and healthy volunteers (e.g., self-medicating academics).
视觉注意理论（TVA；Bundesen 1990）的全报告任务允许独立测量视觉感知处理速度和视觉短期记忆（vSTM）存储容量，而不受运动速度的影响。本研究调查了精神兴奋剂的认知增强效果如何取决于基线表现和个体的血浆水平。
18 名健康志愿者（年龄 20-35 岁）以平衡、双盲交叉设计接受了 40mg 哌醋甲酯、400mg 莫达非尼或安慰剂的单次口服剂量。给药后 2.5-3.5 小时进行视觉呈现字母数组的全报告，同时采集用于分析血浆水平的血样。
哌醋甲酯和莫达非尼均能提高低基线（安慰剂）表现参与者的感知处理速度。这些改善与主观警觉性相关。此外，我们观察到哌醋甲酯在低表现和高表现参与者中的血浆水平依赖性效应存在差异：较高的血浆水平导致低表现参与者的改善更大，而高表现参与者的改善则降低。莫达非尼增强了低表现参与者的视觉短期记忆存储容量。
这是首次药理学研究表明，TVA 任务在认知增强药物后进行高分辨率和重复认知参数估计是有用的。我们的结果证实了先前在低表现者中注意力容量提高的发现，并将基线依赖性模型扩展到哌醋甲酯。精神兴奋剂的血浆水平依赖性效应可以用倒置的 U 形剂量反应关系来建模，这对于预测认知缺陷（如注意缺陷多动障碍）患者和健康志愿者（如自我用药的学者）中精神兴奋剂的认知增强和有害效应具有重要意义。
