Willson Morgan C, Wilman Alan H, Bell Emily C, Asghar Sheila J, Silverstone Peter H
Department of Biomedical Engineering, Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada.
Biol Psychiatry. 2004 Aug 15;56(4):284-91. doi: 10.1016/j.biopsych.2004.06.008.
Dextroamphetamine is known to have profound effects on both subjective and physiologic measurements, but it is unclear to what extent these behavioral changes are a direct result of altered regional brain activation. One method to measure this is to use functional magnetic resonance imaging (fMRI).
In the present study, fMRI was used to measure both the spatial extent of changes (the number of pixels activated) and the magnitude of the blood oxygen level-dependent (BOLD) response. We examined the effects of motor, verbal, memory, and spatial attention task during fMRI in 18 healthy volunteers. Functional MRI measurements were obtained at baseline and again 75 min after an oral dose of 25 mg dextroamphetamine.
Dextroamphetamine caused a decrease in the number of activated pixels and the magnitude of the BOLD response during the three cognitive tasks tested but not during the motor task. These changes were region and task specific.
This is the first study to examine the effect of dextroamphetamine on the number of activated pixels and the BOLD response during the performance of a range of cognitive and motor tasks. Our results suggest that dextroamphetamine causes measurable decreases in brain activity in a variety of regions during cognitive tasks. These changes might be linked to behavioral changes observed after dextroamphetamine administration and could possibly be mediated by alterations in dopaminergic activation.
已知右旋苯丙胺对主观和生理测量均有深远影响，但尚不清楚这些行为变化在多大程度上是大脑区域激活改变的直接结果。一种测量方法是使用功能磁共振成像（fMRI）。
在本研究中，fMRI用于测量变化的空间范围（激活的像素数量）和血氧水平依赖（BOLD）反应的幅度。我们在18名健康志愿者进行fMRI期间检查了运动、言语、记忆和空间注意力任务的影响。在基线时以及口服25mg右旋苯丙胺75分钟后再次进行功能磁共振成像测量。
在测试的三项认知任务中，右旋苯丙胺导致激活像素数量和BOLD反应幅度降低，但在运动任务中未出现这种情况。这些变化具有区域和任务特异性。
这是第一项研究右旋苯丙胺对一系列认知和运动任务执行过程中激活像素数量和BOLD反应影响的研究。我们的结果表明，右旋苯丙胺在认知任务期间会导致多个区域的大脑活动出现可测量的下降。这些变化可能与右旋苯丙胺给药后观察到的行为变化有关，并且可能由多巴胺能激活的改变介导。
