哌甲酯调节正常成年人大脑对go/no-go任务的反应

Methylpheuldate in regulation of motor inhibition in healthy adults

目的 通过比较正常被试服用哌甲酯与安慰剂后执行go/no-go任务时脑区激活的差异,探明5-羟色胺（5-HT）系统在哌甲酯调节动作抑制中的作用.方法 药物（哌甲酯,安慰剂）和任务（go组块,nogo组块）两因素被试内设计.18名男性健康大学生志愿者,服用哌甲酯（20 mg）或安慰剂（维生素B6 20 mg）后,分别在进行功能磁共振（fMRI）扫描的同时执行组块设计的go/no-go任务.结果 哌甲酯可减少眶-前额皮质的激活程度,增加小脑、海马的激活.任务主效应主要体现在与运动有关的脑区,如运动区、丘脑、壳核等.同时,哌甲酯可增强中缝核在抑制任务时的反应,与之有相同激活模式的还有苍白球及左侧小脑.激活阈限均为P＜0.01,未校正,连续体素＞20个.结论 哌甲酯可能通过5-HT系统发挥作用.

Objective The present study was to explore the function of serotonin system in motor inhibition modulated by methylphenidate （MPH）. Methods Eighteen healthy right-handed male university students were recruited. There were two within-subject factors,i.e., medication （MPH vs. vitamin B6 as placebo） and task （go vs. no-go block）. After taking single dose of MPH （20 mg） or placebo （20 mg）,participants were scanned with functional MRI using go/no-go task as stimulus. The go-block contains 16go-trials, and the no-go block 10 go-trials and 6 no-go trials. Each block lasts 32 seconds and repeats 3times. Results The differences of reaction times （RT） and accuracies between MPH and placebo sessions were not statistically significant （ P 〉 0. 1 ）, but the deviation of RT was smaller in MPH than placebo condition （P = 0. 063 ）. MPH mainly decreases the activation in orbital-prefrontal cortex and increases the activation in right cerebellum, hippocampus. Task related main effect was mainly represented in motor areas. The most important, the raphe nuclei showed significant interaction between medication and task.P 〈0.01 ,uncorrected, voxels 〉 20. Analysis of beta values revealed that MPH increased the raphe nuclei response to no-go block, but decreased the response to go block. Pallidum and left cerebellum showed the similar pattern （P〈 0. 05）. Conclusions The results are implied that methylphenidate take effects through serotonin system directly or indirectly.