Nat Neurosci：相似冲动行为牵涉不同大脑区域

近日，国际著名杂志《自然—神经科学》Nature Neuroscience在线刊登的一项报告中指出，相似冲动行为牵涉不同大脑区域。虽然注意力缺失过动症（ADHD）和药物滥用都一直被认为和冲动行为有关，但未成年人的ADHD和药物滥用却分别牵涉到不同的大脑网络。

Robert Whelan等人使用功能性磁共振成像对近2000名未成年人的大脑活动进行追踪，监控他们在突然接收到“停止”指令时，大脑是如何下令停止某个动作的。总体来说，较冲动的人会认为这样的指令比较有难度，药物滥用者和ADHD患者面对“停止”指令的反应时间也会比较长。研究人员发现那些ADHD症状的未成年患者和有过药物滥用、酗酒的未成年人均能同样完成指令，但对于后者而言，其大脑的眼窝前额皮层区域中心的活动会降低。

与此形成对比的是，只有非法药物滥用才能对大脑右下额叶皮层的活动产生影响，而且该区域活动的变化又和药物的滥用频率有关，这意味着这种变化可能是由类似药物的重复使用所导致的，而并不是先天存在的。

这些研究发现表明，一些看上去相同的行为对应在大脑中的活动区域可能有很大的不同。（生物谷Bioon.com）

doi:10.1038/nn.3092
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Adolescent impulsivity phenotypes characterized by distinct brain networks

Robert Whelan, Patricia J Conrod, Jean-Baptiste Poline, Anbarasu Lourdusamy, Tobias Banaschewski, Gareth J Barker, Mark A Bellgrove, Christian Büchel, Mark Byrne, Tarrant D R Cummins, Mira Fauth-Bühler, Herta Flor, Jürgen Gallinat, Andreas Heinz, Bernd Ittermann, Karl Mann, Jean-Luc Martinot, Edmund C Lalor, Mark Lathrop, Eva Loth, Frauke Nees, Tomas Paus, Marcella Rietschel, Michael N Smolka, Rainer Spanagel et al.

The impulsive behavior that is often characteristic of adolescence may reflect underlying neurodevelopmental processes. Moreover, impulsivity is a multi-dimensional construct, and it is plausible that distinct brain networks contribute to its different cognitive, clinical and behavioral aspects. As these networks have not yet been described, we identified distinct cortical and subcortical networks underlying successful inhibitions and inhibition failures in a large sample (n = 1,896) of 14-year-old adolescents. Different networks were associated with drug use (n = 1,593) and attention-deficit hyperactivity disorder symptoms (n = 342). Hypofunctioning of a specific orbitofrontal cortical network was associated with likelihood of initiating drug use in early adolescence. Right inferior frontal activity was related to the speed of the inhibition process (n = 826) and use of illegal substances and associated with genetic variation in a norepinephrine transporter gene (n = 819). Our results indicate that both neural endophenotypes and genetic variation give rise to the various manifestations of impulsive behavior.