When healthy eaters choose broccoli over a Butterfinger, they use a small region in their brains that indulgers don't use.

    That bundle of cells is a clue to the biology of willpower, a new study finds. Like a wagging finger in our heads, the region admonishes us to consider long-term benefits over instant rewards when we make decisions.

    "This is the first time people have looked at the mechanism of self-control in people who are making real-life decisions," said Todd Hare, a Caltech neuroscientist who led the study.

    To zero in on the nodule that imposes willpower, Hare and his colleagues scanned the brains of 37 people who called themselves dieters. During the scans, the subjects pored over 50 photos of foods. They rated the foods according to taste and healthiness.

    Some foods, such as Wheat Thins and granola, earned strong "neutral" marks in both categories. For the final test, scientists showed each volunteer a food that they had labeled "neutral" and asked them to choose between it and each of 49 other foods.

    When the results were in, the scientists divided the dieters into two groups: those who had self-control and those who didn't. Those with self-control chose healthy foods over tasty foods. Those with no self-control opted for flavor.

    Every one of the volunteers used a part of their brains called the ventromedial prefrontal cortex, the scans revealed. It's a squiggly-shaped region behind the forehead. Those who exercised restraint, however, also used a part of the brain called the dorsolateral prefrontal cortex, a smaller lump of brain cells buried further back. It has been associated with working memory and meeting goals.

    The results were detailed in the May 1 issue of the journal Science.

    "It's unlikely that self-control is just one little nodule in the brain," cautioned Scott Huettel, neuroscience professor at Duke University who was not involved in the study. "There are undoubtedly many things that contribute to the way people make decisions." However, Huettel added, the regions Hare's team studied seemed to correspond to the decisions people make.

    The findings could lead to new treatments for over-eaters, drug addicts and smokers, among others. In fact, Hare's team is now developing brain-training exercises in an effort to help people improve their self-control. In the future, this kind of research could also bear on legal decisions, lending insight into how much responsibility we can claim for the quality of our decisions.

    當(dāng)食量正常的人選擇吃花椰菜，卻不選朱古力威化餅的時(shí)候，他們使用了大腦中的一個(gè)小區(qū)域，那是暴食者不用的區(qū)域。

    一項(xiàng)新的研究發(fā)現(xiàn)，大腦中的那束細(xì)胞提供了生物學(xué)所說(shuō)的意志力。那個(gè)區(qū)域好似在腦中擺動(dòng)的手指，告誡我們?cè)谧龀鰶Q定的時(shí)候要考慮長(zhǎng)遠(yuǎn)利益，不要貪圖一時(shí)的享受。

    托德·海爾是領(lǐng)導(dǎo)此次研究的加利福尼亞理工學(xué)院神經(jīng)系統(tǒng)科學(xué)家。他說(shuō)，“這是人們第一次觀察到在現(xiàn)實(shí)生活中做決定時(shí)人的自我控制機(jī)制。”

    為了找準(zhǔn)實(shí)施意志力的結(jié)節(jié)，海爾和同事們掃描了37位自稱(chēng)為節(jié)食者的受試者大腦。在掃描過(guò)程中，受試者仔細(xì)研究五十幅食物照片，根據(jù)其味道和健康程度將其分類(lèi)。

    某些味道和健康程度俱佳的食物，比如小麥片和格蘭諾拉麥片，令人信服地獲得“中性”的標(biāo)志。作為最后的測(cè)試，科學(xué)家們向每個(gè)志愿者出示一個(gè)他們貼上“中性”標(biāo)簽的食物，并請(qǐng)他們?cè)谶@種食物和其它49種食物之間一個(gè)個(gè)做出選擇。

    結(jié)果出來(lái)后，科學(xué)家們把節(jié)食者分為兩組：擁有自制力的和沒(méi)有自制力的。那些擁有自制力的人選擇健康食品多過(guò)美味食品。那些沒(méi)有自制力的人選擇的是口味。

    掃描顯示，每個(gè)志愿者都使用了被稱(chēng)為腹內(nèi)側(cè)前額皮層的那部分大腦。那是前額后部彎曲形區(qū)域。而那些顯示出自制力的人還使用了被稱(chēng)為背外側(cè)前額葉皮層的那部分大腦，那是深埋于后腦的較小的腦細(xì)胞結(jié)節(jié)。它與產(chǎn)生記憶和達(dá)到目標(biāo)有關(guān)系。

    五月一日的《科學(xué)》雜志詳細(xì)刊載了此項(xiàng)研究結(jié)果。

    杜克大學(xué)神經(jīng)系統(tǒng)科學(xué)教授斯科特·胡特爾沒(méi)有參與研究。他告誡說(shuō)，“自我控制不大可能只是大腦中的一個(gè)小結(jié)節(jié)。毫無(wú)疑問(wèn)，有助于人們做出決定的因素還有很多。”他補(bǔ)充說(shuō)，不管怎樣，海爾小組研究的區(qū)域似乎對(duì)應(yīng)了人們做決定的區(qū)域。

    研究結(jié)果可能會(huì)引出新的方法，用于治療飲食過(guò)量者、吸毒者和吸煙者等等。事實(shí)上，海爾小組正在開(kāi)發(fā)大腦訓(xùn)練，試圖幫助人們提高自制力。將來(lái)，這種研究可能也會(huì)具有法律決策性，能讓我們深入了解自己的決策所要承擔(dān)的責(zé)任。