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.

    當食量正常的人選擇吃花椰菜，卻不選朱古力威化餅的時候，他們使用了大腦中的一個小區域，那是暴食者不用的區域。

    一項新的研究發現，大腦中的那束細胞提供了生物學所說的意志力。那個區域好似在腦中擺動的手指，告誡我們在做出決定的時候要考慮長遠利益，不要貪圖一時的享受。

    托德·海爾是領導此次研究的加利福尼亞理工學院神經系統科學家。他說，“這是人們第一次觀察到在現實生活中做決定時人的自我控制機制。”

    為了找準實施意志力的結節，海爾和同事們掃描了37位自稱為節食者的受試者大腦。在掃描過程中，受試者仔細研究五十幅食物照片，根據其味道和健康程度將其分類。

    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”的標志。作為最后的測試，科學家們向每個志愿者出示一個他們貼上“中性”標簽的食物，并請他們在這種食物和其它49種食物之間一個個做出選擇。

    結果出來后，科學家們把節食者分為兩組：擁有自制力的和沒有自制力的。那些擁有自制力的人選擇健康食品多過美味食品。那些沒有自制力的人選擇的是口味。

    掃描顯示，每個志愿者都使用了被稱為腹內側前額皮層的那部分大腦。那是前額后部彎曲形區域。而那些顯示出自制力的人還使用了被稱為背外側前額葉皮層的那部分大腦，那是深埋于后腦的較小的腦細胞結節。它與產生記憶和達到目標有關系。

    五月一日的《科學》雜志詳細刊載了此項研究結果。

    杜克大學神經系統科學教授斯科特·胡特爾沒有參與研究。他告誡說，“自我控制不大可能只是大腦中的一個小結節。毫無疑問，有助于人們做出決定的因素還有很多。”他補充說，不管怎樣，海爾小組研究的區域似乎對應了人們做決定的區域。

    研究結果可能會引出新的方法，用于治療飲食過量者、吸毒者和吸煙者等等。事實上，海爾小組正在開發大腦訓練，試圖幫助人們提高自制力。將來，這種研究可能也會具有法律決策性，能讓我們深入了解自己的決策所要承擔的責任。