美国密歇根大学的研究人员最近发现，在老鼠脑部存在着一个“快感点”（pleasure spot）。研究人员认为，这个发现或许会对“人们吃下的食物如何转化为快感”这个问题具有启迪作用。

    据美联社12月20日报道，密歇根大学的精神生物学研究人员苏珊娜·派斯娜和肯特·贝利吉发现，老鼠脑部的这个“快感区域”会使甜的味道较之其它味道更受欢迎。

    研究人员指出，甜味本身仅仅只是种感觉而已。而品尝到甜的东西所带来的快乐实际上是在大脑内部产生的。脑部的神经系统会积极地将愉快添加到这种感觉上，从而产生一种“喜欢”的反应。研究显示，在脑部伏隔的一个负责食欲的大块区域内，存在着一个“快感点”。对此，贝利吉表示：“在一个较大的对食物产生需求的区域内，隐藏着一个对食物发生喜好的区域。”

    研究过程中，派斯娜和贝利吉对老鼠的脑部进行了药物显微注射，刺激老鼠脑部感受镇静物质或类似吗啡的物质的受体，从而导致附近的神经细胞刺激特殊的基因，并使其开始产生蛋白。

    接受显微注射后，老鼠就会吃下更多的东西。研究人员使用一种新的绘制技术，查明显微注射的刺激促使“喜欢”的反应增强，是发生在老鼠脑部的哪个区域。这个快感区域比增加食欲的区域要小得多。贝利吉表示，这项研究最终可能被应用到治疗饮食紊乱症上。

    研究人员还说，他们在试验中使用的是甜味的食物，但使用任何所喜爱的食物都可能得到相同的效果。

    报道说，这一研究结果被发表在新一期的《精神科学杂志》上。 

    Researchers at the University of Michigan have found a "pleasure spot" in the brains of rats that may shed light on how food translates into pleasure for humans.

    The spot in rats' brains makes sweet tastes more "liked" than other tastes, biopsychology researchers Susana Pecina and Kent Berridge found.

    The pair detailed their findings in the Dec. 14 issue of the Journal of Neuroscience.

    Sweetness by itself is merely a sensation, they note. Its pleasure arises within the brain, where neural systems actively paint pleasure onto the sensation to generate a "liking" reaction.

    The study pinpointed a pleasure spot within a larger part of the brain responsible for appetite in the nucleus accumbens, the lower front of the brain.

    "There's a liking cube tucked within a larger wanting cube," Berridge said in a telephone interview.

    Previously, scientists knew the general part of the brain that was responsible for pleasure and appetite. But they did not know whether those functions were separable, Berridge said.

    "In our experience, they're intertwined and inseparable," Berridge said. "In our brain, they are separable."

    Pecina and Berridge made microinjections into rats' brains of drugs that stimulated receptors for opioids, or heroin-like substances, causing nearby neurons to activate particular genes that began producing proteins.

    The microinjections caused rats to eat more food soon afterward. Using a new mapping technique, the researchers pinpointed where in the brain the microinjections activated increased liking reactions. The pleasure spot was much smaller than the larger appetite-increasing zone.

    Berridge said the study could ultimately have applications for treating eating disorders.

    The researchers used sweet things in their study, but Berridge noted the reaction would be the same with any liked food.