进展】《Nature》：催产素能增强人类互信

psychology

]【进展】《Nature》：催产素能增强人类互信
据报道，瑞士科学家发现一种名为缩宫素的荷尔蒙，不但有助母亲哺乳，并可作为“诚信药物”减轻人的疑心。

　　缩宫素可激活男女掌管情绪、特别是诚信和社交关系的神经网络。研究员以实验室哺乳类动物进行研究，发现注入缩宫素的动物在“交友”上较少戒心。

　　为研究缩宫素对人类的影响，研究员招募了178名男学生参与实验，一半自愿者要吸入缩宫素，另一半则吸入无害的假药。之后，自愿者分为一对对参与真实金钱游戏，分别担任投资者及受托人。投资者获派一大叠现金，当他将部分现金交给受托人，研究员会将现金增加两倍。受托人之后或会收到部分或全部赏金，或与投资者共享，所以投资者交出现金前，必须信任受托人不会独吞赏金。

　　结果显示，45%投资者显示出“最高信用水平”，但服用假药只有21%。但当自愿者被安排与计算机玩同一游戏，服用缩宫素和假药者同样忧虑交出大量现金，显示缩宫素只会增加人与人间的信任。

　　科学家称有关研究可帮助患有自闭症和各种恐惧症的人，但爱荷华大学的专家达马西奥则担心政客会在大选期间，大规模向选民洒上缩宫素，以吸纳选票。

msnbc6月1日消息，瓶装的信任感？这听上去像是某个推销员的白日梦，如同不老泉的神话或对时尚饮食的疯狂追求。但，不！瑞士和美国科学家通过实验已经证明了含有催产素的鼻喷雾剂能促进人们的信任感。只要按几下喷雾剂，人们就明显更相信对方。尽管没有任何从中获益的保障，他们仍愿意付对方钱。研究者们知道，他们的发现可能被反对派艺术家甚至为了选票而立场摇摆不定的政客们所滥用。

催产素由脑组织分泌，其合成部位在下丘脑。下丘脑虽然体积不大，却非常重要，它位于大脑深部，控制着生物的重要生理功能，例如饥饿、口渴和体温，以及在恐惧或愤怒等情感下内脏的应激反应。长期以来人们一直认为催产素对两性而言都是直接与生殖功能相关的激素。无论人类还是动物，催产素都能在分娩过程中促使子宫收缩以及泌乳。另外，男女两性在性行为中也分泌催产素。无论分娩过程中还是分娩后，脑脊液中都能测出催产素存在，实验表明催产素参与生物化学过程。婴儿需要多年照顾，因此母亲的身体产生催产素以适应养育婴儿的要求。

近年来，科学家们怀疑催产素是否有其他方面的作用，是否影响人们形成亲密关系－--特别是它能否能激发信任感。实验中，研究者设法使催产素进入受试者脑部，观察是否能激发受试者的信任感。他们将人工合成催产素以喷雾剂的形式通过受试者粘膜，越过血脑屏障进入他们的大脑。研究者称催产素剂量控制在无害水平，对受试者体内催产素浓度只有短暂影响。来自苏黎士大学的178名年龄20多岁的男性志愿者参加了实验，分别对他们使用了催产素制剂或安慰剂。第一次实验中，进行一项游戏：受试者中的一位“投资人”可选择一个“保管员”存放最多12笔钱款，每笔钱款相当于0.4瑞士法郎，或32美分。保管员则将投资者钱款数量乘以三，然后决定自己分享其中多大部分。保管员不确定他是否将返还钱款给投资者。

在使用催产素组的29名受试者中，45%的人投资了12笔钱款的最大数额，用研究者的话说，就是达到了“最大程度的信任”。只有21%的受试者投资少于8笔钱款，表现出较低的信任度。相比较地，安慰剂组的行为模式正相反。只有21%的受试者投资了最大额度金钱，45%的人投资程度较低。总的来说，接受催产素组的受试者投资额度较安慰剂组高出17%。在第二个实验中，受试者面对同样的抉择。但这一次，保管员换成了电脑程序。研究者以此观察催产素是否真正促进了人们的社会互动还是仅仅激发冒险精神。结果是：催产素组和安慰剂组的表现相仿，两组的平均投资钱款为7.5笔。

费尔及其同事报道：“催产素可增进人们的潜在信任感”。科学家计划使用大脑成像技术进行新一轮实验。费尔说：“我们已经知道了催产素具有行为效应，现在我们想知道的是这种效应背后的神经回路。”
一项新的研究发现，只需闻一下一种名为催产素的激素，便可以增强一个人的信任感。这项研究表明，与其他方法相比，催产素疗法能够帮助严重抑郁症患者更好地向他们的精神治疗医师敞开心扉。

科学家发现，催产素在社会关系中扮演了重要角色，例如，在“一夫一妻制”的草原田鼠中，催产素能够增进雌鼠与雄鼠间的感情，同时在雌鼠中，催产素还能够激发“省亲”行为。但是有关催产素在人体中的功能，科学家却知之甚少。

由瑞士苏黎世大学的经济学家Ernst Fehr领导的一个研究小组在男学生中进行了一场信任游戏。他们将两名相互陌生的男学生分为一组，其中一个扮演“投资人”——他拥有少数金额的现金，另一个则扮演“保管人”。如果投资人选择将他的一部分现金交给保管人，那么这些钱在到达保管人手中时将变为原来金额的3倍。保管人随后便可以选择将他的利润退还一些给投资人，也可以选择不退。如果这两名学生之间相互信任且合作的话，他们都将从这个游戏中获利。但是由于他们是通过计算机匿名进行这场游戏的，并且每一组学生只面对面地进行过一次这种游戏，因此根据基本经济学理论推断，保管人将隐藏他的利润——而投资人则由于担心这一问题的发生，因此在最开始便不会给出一分钱。但是信任和正直似乎占了上峰：投资人移交了他们的现金，而保管人则返还了他们的利润，最终每个人都从中获得了好处，大量的研究都得出了这一结果。

研究人员在6月2日出版的《自然》杂志上报告说，与对照组相比，那些闻了催产素的投资人交出的钱比前者多了20%，并且那些决定将全部钞票统统移交的投资人的比例也翻了一倍。更进一步的测试表明，这种激素通过使投资人不再担心被出卖而产生作用。尽管催产素在保管人那里并没有引发慷慨的行为，但这种激素使得他们在返还的利润上与投资人并无差别。

美国佐治亚州亚特兰大市Emory大学的神经生物学家Larry Young认为，在这一点上，并没有直接的证据表明，催产素对动物的社会行为所产生的影响同样适用于人类社会。他说，“我们只是看到了催产素对于人类所产生的作用的冰山一角。”

这看起来像不像小说里的情节：一个坏人向愚人城的市民喷洒了一种信任激素，于是全体市民向他贡献出自己所有的钱，银行、股市、甚至政府全部崩溃。

很科幻吧？但瑞士和美国科学家的最新实验证明：喷一点催产素，就能刺激人们产生信赖感。科学家称，这一发现可能有助于治疗孤独症等疾病。

使人产生信任感

瑞士苏黎世大学及其美国同行们给一批男性受试者喷洒了人造催产素。受试者被分成“投资者”和“托管人”，投资者握有12份钱，每份钱相当于32美分，而托管人据说能使他们的钱增值3倍。

结果，在使用催产素的29人中，45％把自己的钱全部用作了投资，也就是“最大的信任”。只有21％的受试者信任水平较低，投资了不到8份钱。而对照组的信任水平则恰恰相反，只有21％的受试者全部进行了投资，而45％投资了不到8份钱。

有望治疗孤独症

在最新一期《自然》杂志上，研究人员报告了他们的发现：催产素会引起信任感的大幅度增长。不过实验显示，催产素只能让人对人产生信任，而无法让受试者对机器产生信任。另外，坠入爱河的情侣体内催产素的含量要高于其他人。据悉，研究人员还将在新一轮实验中研究大脑在这过程中的具体机制。

有科学家称，研究成果揭示催产素可能能用来治疗孤独症，孤独症患者就是缺乏对人的信任感。催产素还有可能用来治疗更罕见的疾病，如威廉斯氏症的患儿在接受催产素治疗后，会不再害怕陌生人的接近。

【原文】Scientists study ‘trust in a bottle’
Oxytocin makes people more willing to bond

MSOE Center For BioMolecular Modeling
A model shows the molecular structure of oxytocin.
The Associated Press
Updated: 2:56 p.m. ET June 1, 2005LONDON - Trust in a bottle? It sounds like a marketer's fantasy, like the fabled fountain of youth or the wild claims of fad diets. Yet that's what Swiss and American scientists demonstrate in new experiments with a nasal spray containing the hormone oxytocin.

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After a few squirts, human subjects were significantly more trusting and willing to invest money with no ironclad promise of a profit.

The researchers acknowledged their findings could be abused by con artists or even sleazy politicians who might sway an election, provided they could squirt enough voters on their way to the polls.

\"Of course, this finding could be misused,\" said Ernst Fehr of the University of Zurich, the senior researcher in the study, which appears in Thursday's issue of the journal Nature. \"I don't think we currently have such abuses. However, in the future it could happen.\"

Therapy for social phobias?
Other scientists say the new research raises important questions about oxytocin's potential as a therapy for conditions like autism or social phobias, in which trust is diminished. Or, perhaps the hormone's activity could be reduced to treat more rare diseases, like Williams' Syndrome, in which children have no inhibitions and approach strangers fearlessly.

\"Might their high level of trust be due to excessive oxytocin release?\" asks University of Iowa neurologist Antonio Damasio, who reviewed the experiments for Nature. \"Little is known about the neurobiology of trust, although the phenomenon is beginning to attract attention.\"

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Oxytocin is secreted in brain tissues and synthesized by the hypothalamus. This small but crucial feature, located deep in the brain, controls biological reactions like hunger, thirst and body temperature, as well as visceral fight-or-flight reactions associated with powerful, basic emotions like fear and anger.

For years oxytocin was considered to be a straightforward reproductive hormone found in both sexes. In both humans and animals, this chemical messenger stimulates uterine contractions in labor and induces milk production. In both women and men, oxytocin is released during sex, too.

Then, elevated concentrations of the hormone also were found in cerebrospinal fluid during and after birth, and experiments showed it was involved in the biochemistry of attachment. It's a sensible conclusion, given that babies require years of care and the body needs to motivate mothers for the demanding task of childrearing.

Testing the trust factor
In recent years, scientists have wondered whether oxytocin also is generally involved with other aspects of bonding behavior — and specifically whether it stimulates trust.

In the experiments, the researchers tried to manipulate people's trust by adding more oxytocin to their brains. They used a synthetic version in a nasal spray that was absorbed by mucous membranes and crossed the blood-brain barrier. Researchers say the dose was harmless and altered oxytocin levels only temporarily.

A total of 178 male students from universities in Zurich took part in a pair of experiments. All the volunteers were in their 20s. They got the oxytocin or a placebo.

In the first experiment, they played a game in which an \"investor\" could choose to hand over to a \"trustee\" up to 12 units of money that are each equal to 0.40 Swiss franc, or about 32 cents. The trustee triples the investor's money, then gets to decide how much of the proceeds to share. The trustee can't be certain how much — if anything — he will get in return.

Of 29 subjects who got oxytocin, 45 percent invested the maximum amount of 12 monetary units and, in the researchers' words, showed \"maximal trust.\" Only 21 percent had a lower trust level in which they invested less than 8 monetary units.

In contrast, the placebo group's trust behavior was reversed. Only 21 percent of the placebo subjects invested the maximum, while 45 percent invested at low levels.

Overall, the investors who received oxytocin invested 17 percent more than investors who received a placebo.

Computer comes into play
In a second experiment, investors faced the same decision. But this time, the trustee was replaced by a computer program in an effort to see whether the hormone promoted social interaction, or simply encouraged risk-taking.

With the computer, the oxytocin and placebo groups behaved similarly, with both groups investing an average of 7.5 monetary units.

\"Oxytocin causes a substantial increase in trusting behavior,\" Fehr and his colleagues reported.

Researchers said they are performing a new round of experiments using brain imaging. \"Now that we know that oxytocin has behavioral effects,\" Fehr said, \"we want to know the brain circuits behind these effects.\"