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.

    当食量正常的人选择吃花椰菜，却不选朱古力威化饼的时候，他们使用了大脑中的一个小区域，那是暴食者不用的区域。

    一项新的研究发现，大脑中的那束细胞提供了生物学所说的意志力。那个区域好似在脑中摆动的手指，告诫我们在做出决定的时候要考虑长远利益，不要贪图一时的享受。

    托德·海尔是领导此次研究的加利福尼亚理工学院神经系统科学家。他说，“这是人们第一次观察到在现实生活中做决定时人的自我控制机制。”

    为了找准实施意志力的结节，海尔和同事们扫描了37位自称为节食者的受试者大脑。在扫描过程中，受试者仔细研究五十幅食物照片，根据其味道和健康程度将其分类。

    某些味道和健康程度俱佳的食物，比如小麦片和格兰诺拉麦片，令人信服地获得“中性”的标志。作为最后的测试，科学家们向每个志愿者出示一个他们贴上“中性”标签的食物，并请他们在这种食物和其它49种食物之间一个个做出选择。

    结果出来后，科学家们把节食者分为两组：拥有自制力的和没有自制力的。那些拥有自制力的人选择健康食品多过美味食品。那些没有自制力的人选择的是口味。

    扫描显示，每个志愿者都使用了被称为腹内侧前额皮层的那部分大脑。那是前额后部弯曲形区域。而那些显示出自制力的人还使用了被称为背外侧前额叶皮层的那部分大脑，那是深埋于后脑的较小的脑细胞结节。它与产生记忆和达到目标有关系。

    五月一日的《科学》杂志详细刊载了此项研究结果。

    杜克大学神经系统科学教授斯科特·胡特尔没有参与研究。他告诫说，“自我控制不大可能只是大脑中的一个小结节。毫无疑问，有助于人们做出决定的因素还有很多。”他补充说，不管怎样，海尔小组研究的区域似乎对应了人们做决定的区域。

    研究结果可能会引出新的方法，用于治疗饮食过量者、吸毒者和吸烟者等等。事实上，海尔小组正在开发大脑训练，试图帮助人们提高自制力。将来，这种研究可能也会具有法律决策性，能让我们深入了解自己的决策所要承担的责任。