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【Science News——编译】警惕的大脑 ScienceNow: 200
警惕的大脑
我们都有这样一种相似的经历：在高速公路转弯的时候我们会下意识的踩刹车，或者是在下自动扶梯的时候我们会很自然的看着我们脚下的台阶。现在，研究人员称他们已经发现大脑中促使我们在复杂环境下格外留心的区域。
前扣带回皮质（ACC）是定位在靠近大脑额叶顶部的部分。其功能一直被认为是用来监测动作中的错误，这就像机场传送带上的监测器对运送错误的手提箱进行监测。现在，联合采用计算机辅助模型和脑成像技术，密苏里州圣路易斯华盛顿大学的认知神经科学家Joshua Brown和Todd Braver已经证实ＡＣＣ同样具有预报的功能，这种功能基于个体既往的经历。
这项研究发表在本期的Ｓｃｉｅｎｃｅ上。研究人员让受试者注视着显示有一条水平线的电脑显示器，数秒钟后显示器内出现一个箭头。在箭头一出现后受试者必须按下左手或是右手的显示箭头方向的按钮。在某些实验中，第一次出现某个方向的箭头后便主要出现其反向的箭头，在显示器的右上方显示与第一次箭头方向相反的箭头。在这种情况下受试者必须按反方向的按钮。第一次和第二次箭头间延迟的时间越长，受试者按中第一按钮的正确率越高，而随后他们改变方向的反应则越来越差。
用同一颜色箭头进行这一试验时相对比较简单，而用不同颜色进行试验时错误出现得更多。受试者大脑的功能性磁共振显示颜色变化导致出错增多时ＡＣＣ区变得非常活跃，在数百次试验中这种效应逐渐增强。
“当产生错误的机会增高时ＡＣＣ会从以往的经历中吸取经验，”Ｂｒｏｗｎ说。他推测ＡＣＣ区能将这种警告传到大脑其他部分，从而导致对行为的调节，例如在高速公路上的减速。
“这是一项很有创新性的研究，接下来面临的挑战是搞清楚ＡＣＣ区的详细功能，”费城宾夕法尼亚大学的心理学家Ｍａｔｔｈｅｗ Ｂｏｔｖｉｎｉｃｋ说。
--YUDHIJIT BHATTACHARJEE
原文：
http://sciencenow.sciencemag.org/cgi/content/full/2005/218/6
18 February 2005
The Cautious Brain
It's a familiar feeling: the cautious impulse to hit the brakes when the highway begins to curve, or the urge to watch your step when stepping off an escalator. Now, researchers say they've identified the region of the brain that prompts us to be extra careful in tricky situations.
The anterior cingulate cortex (ACC)-an area located near the top of the brain's frontal lobes, which has long been known to help detect mistakes in action--such as hauling the wrong suitcase off an airport carousel. Now, using a combination of computational modeling and brain imaging studies, cognitive neuroscientists Joshua Brown and Todd Braver at Washington University in Saint Louis, Missouri, have shown that the ACC can also predict based on past experience-- how likely the person is to goof up on a given task.
For the study, published today in Science, the researchers showed participants a computer screen with a horizontal line that developed an arrowhead after a few seconds. As soon as this happened, participants had to press a right or a left button corresponding to the direction of the arrow. On some trials, a more prominent second arrow appeared soon after the first, positioned right above the first arrow and pointing in the opposite direction. If that happened, participants had to change gears and press the other button. The longer the delay between the first and the second arrow, the more committed the participants became to pressing the first button and the harder it was for them to change their response mid stream.
Easier trials displayed arrows of a particular color, while those with a greater chance of error used a different color. Functional MRI of the participants' brain activity showed that the ACC became more active when the color associated with the higher error rate was presented--an effect that grew stronger over hundreds of trials.
? "The ACC seems to learn from experience when the chances of making a mistake might be high," says Brown. He speculates that the ACC communicates this alert to other parts of the brain, leading to an adjustment of behavior such as slowing down on the highway.
It's "a clever and innovative study," says Matthew Botvinick, a psychologist at the University of Pennsylvania in Philadelphia. "The challenge now is to come up with a comprehensive account of ACC function."
--YUDHIJIT BHATTACHARJEE
Related sites
Joshua Brown's homepage 标题错了
是转载还是源创翻译？？？？ 是我自己译的
Cautious我不知该成译“警惕的”还是“谨慎的"
但根据意思还是“警惕的”比较好
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作者:admin@医学,生命科学 2011-06-03 05:14
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