为什么青少年游戏玩家大脑结构很特别？

　　疯狂热爱电子游戏的青少年玩家比他们的同龄人有更大的腹侧纹状体区域，不过这是玩游戏的结果，还是原因呢？

　　经常玩电子游戏的青少年的腹侧纹状体灰质面积，比那些较少玩游戏的同龄人更大。

　　在转化精神病学（Translational Psychiatry）2011年11月15日在线杂志上发表的一个研究中，比利时根特大学的研究者对德国柏林招募的154名健康的14岁中学学生（72名男性，82名女性）进行了评估，以这些学生的每周平均游戏时间----9个小时为标准，将他们分到常玩游戏组和不常玩游戏组。通过结构磁共振成像，研究者发现常玩电子游戏组的腹侧纹状体灰质明显高于不常玩游戏组。

　　“较高水平的腹侧纹状体灰质与玩电子游戏的联系，可能反映了转换的奖励过程处理，而且表现了自适应神经的可塑性。”心理学和教育科学研究所根功能和代谢成像学院实验心理学系的Simone Kühn及其同事如是说。

　　不过玩游戏和更大的灰质区域谁是因谁是果呢？Kühn和同事认为这个横截面研究并不能确定，常玩游戏玩家的较大腹侧纹状体灰质区域是否会导致他们沉溺于游戏，也不能确定这是不是长期全神贯注于电子游戏所带来的结果。

　　“腹侧纹状体灰质区域较大的个人可能在开始玩游戏时，从中感受到更大的回报，”他们写道，“这也可能反过来会促进他们学习技巧，从而在游戏中得到更大的回报。”

　　研究者还通过两个研究，来探索这一现象。首先，他们分析了在一个金钱诱因延迟任务中的大脑活动，并用一个反应时间任务来测量回报期望和反馈中的大脑活动。他们发现当告知多少分会赢得任务时，常玩游戏的人大脑活动更高。这个活动所处的区域，与观察到的他们更大的腹侧纹状体区域相重叠。

　　他们还进行了剑桥赌博任务（Cambrige Gambling Task）的行为测试，这个行为任务的目的是测量不同类别的风险决策的制定。研究者观察到思考时间与纹状体灰质之间的显着负相关，这意味着腹侧纹状体区域灰质较大的参与者制定决策更快。

　　Kühn和同事们认为，“我们的研究能够帮助理解过度（但非病态）玩电子游戏的结构性和功能性基础，以及腹侧纹状体在‘行为’上瘾中所起的作用。”

　　这一研究参与者是在IMAGEN中招募的，IMAGEN是一个始于2007年12月的欧洲多中心遗传--神经成像研究项目，由欧洲共同体六框架计划资助，目前已经在英国、法国、爱尔兰和德国招募了2000名14岁青少年，从而研究青少年的心理健康和冒险行为。

　　译文：

　　Teenagers who frequently play video games have more ventral striatal gray matter volume than their peers who play less often.

　　In a study published online November 15, 2011, in Translational Psychiatry, researchers based at Ghent University in Belgium assessed 154 healthy 14-year-old adolescents （72 males and 82 females） recruited from secondary schools in Berlin, Germany. They classified participants as frequent or infrequent players based on whether they played above or below the median of nine hours per week. Using structural magnetic resonance imaging, the researchers found significantly higher ventral striatal gray matter for frequent vs. infrequent video gamers.

　　“The association of video-game playing with higher ventral striatum volume could reflect altered reward processing and represent adaptive neural plasticity,” said Simone Kühn, of the Department of Experimental Psychology at the Ghent Institute for Functional and Metabolic Imaging’s Faculty of Psychology and Educational Sciences, and colleagues.

　　But which came first, game-playing skills or more voluminous gray matter? Kühn and colleagues said they could not determine with this cross-sectional study whether the volumetric differences in ventral striatum between frequent and moderate video-game players are preconditions that lead to a vulnerability for preoccupation with gaming or are a consequence of long-lasting activation during gaming.

　　“Individuals with higher ventral striatum volume might experience video gaming as more rewarding in the first place,” they wrote. “This in turn could facilitate skill acquisition and lead to further reward resulting from playing.”

　　The researchers also characterized the functional involvement of the regions of interest by performing two analyses. First, they analyzed brain activity occurring during a Monetary Incentive Delay task, a reaction-time task used to assess brain activity during reward anticipation and feedback. They found higher activity in the frequent video-game players while the players were being told how many points they’d won with the task. This activity was located in a region overlapping that in which they had observed higher striatal gray matter volume.

　　They also evaluated behavioral measures of the Cambridge Gambling Task, a behavioral task intended to measure risky decision making by subjects. A significant negative correlation between deliberation time and striatal gray matter volume was observed. The researchers said this finding indicates that participants with higher ventral striatum gray matter volume were faster in decision making.

　　“Our results have implications for the understanding of the structural and functional basis of excessive but nonpathological video-game playing and the role of the ventral striatum in ‘behavioral’ addiction,” said Kühn and colleagues.

　　Participants were recruited within the scope of the IMAGEN project, a European multicenter genetic-neuroimaging study that has recruited 2,000 14-year-old children in England, France, Ireland, and Germany since its inception in December 2007 to investigate mental health and risk-taking behavior in teenagers. The IMAGEN study receives funding from the European Community’s Sixth Framework Program.