來自斯坦福大學(xué)的神經(jīng)學(xué)家Brian Knutson教授（http://www-psych.stanford.edu/~knutson/,）和他的同事Camelia Kuhnen（http://www.stanford.edu/~camelia/,）發(fā)現(xiàn)大腦中“戰(zhàn)爭”會影響冒險決定。這一有趣的結(jié)果公布在8月31日Neuron上,。
當(dāng)我們在一個冒險和保守的經(jīng)濟(jì)投資中選擇時,，我們大腦中有兩個部分會進(jìn)行激烈的競爭。這時對大腦作一個簡單的掃描就能在一個人要做出決定前的幾秒鐘內(nèi)預(yù)測到底這個人會的選擇：當(dāng)大腦中歡樂打敗了焦慮,，就會選擇去冒險,。
大腦中的這兩個部分中的其中一個是稱為依伏神經(jīng)核（nucleus accumbens）的花生狀區(qū)域，這個區(qū)域由分子多巴胺填充,，當(dāng)我們感覺到高興時就會被激活,。并且這一區(qū)域也在藥物上癮中扮演著關(guān)鍵角色,。另一個部分是前丘腦，這是個在焦慮,，擔(dān)心等壞感覺產(chǎn)生時會被激活的區(qū)域,。而且與前一部分相對應(yīng)，前丘腦在開啟物理疼痛感知中作用明顯,。
為了具體了解情況,，研究人員通過一個現(xiàn)金冒險游戲比較了這兩個區(qū)域的相互作用。在實(shí)驗(yàn)當(dāng)中,，20名參與者可以按下電腦上的按鈕選擇是進(jìn)行安全的投注（保證他們能獲得1美元的回報）,，還是另兩個賭注，其中一個是在一輪當(dāng)中可以有一半的機(jī)會贏得10美元,，但要冒25%的險失去10美元,，另一個是相反的：一般機(jī)會失去10美元，四分之一的機(jī)會贏得10美元,。在這個過程中,，研究人員并沒有告訴參與者具體的賭注，讓游戲更具冒險性,。但游戲結(jié)束時,，參與者的大腦會用功能性磁力印象儀拍下照片。結(jié)果表明,，依伏神經(jīng)核在作出一個冒險決定前2秒會被激活,，而當(dāng)參與者選擇保守投注時，下丘腦較活躍,。
原文：
http://www.nature.com/news/2005/050829/full/050829-12.html
Deciding between a risky financial investment and a safe one sets two parts of the brain into competition, say researchers in California.
As centres for pleasure and anxiety battle it out, a simple brain scan of the two can actually predict what a person will chose to do a few seconds before they do it: when joy beats worry in our brain, a risky decision is made.
Studies of how the mind handles risky behaviour have highlighted a number of neural hotspots. One is a peanut-sized region of the brain called the nucleus accumbens, which is loaded with the molecule dopamine and becomes active in anticipation of pleasure. The nucleus accumbens is known to play a role in the addictive effect of drugs.
Another region, known as the anterior insula, is stimulated in anticipation of a bad sensation. This area lights up in those predicting the onset of physical pain, and in generally anxious individuals.
Neuroscientist Brian Knutson of Stanford University and his colleague Camelia Kuhnen sought to compare how these two brain regions interact by asking 20 volunteers to play an investment game for a cash reward.
Risky Business
The participants pushed a computer button to select either a safe bond, which was guaranteed to earn them $1 in any given round, or one of two stocks. One stock had a 50% chance of earning the player $10 in a single round, and a 25% chance of losing him or her $10. The other carried a 50% chance of losing $10 and a 25% chance of winning it. But the scientists did not reveal which stock was which, making it an even riskier game to play.
As the participants completed the task, a machine took snapshots using functional magnetic resonance imaging, which revealed the active parts of the brain.
The results showed that the nucleus accumbens lit up about two seconds before a risky investment was made. When the anxious anterior insula was more active, the participants stuck to the safer choice.
The results of this study, which appear in the journal Neuron, reveal a previously unknown interplay between these two brain regions.
The thing to do is to work out when and why one part of our brain outdoes the other, says Martin Paulus of the University of California, San Diego, who has studied the role of the anterior insula in decision making. "The ultimate question is: when do you listen to one circuit and not the other?" he says.
The answer might help everyone from psychologists aiming to dull anxiety in nervous patients, to marketing gurus attempting to get customers to live dangerously.
