and those with bacteria-free guts were obviously free of the bug altogether, the valproic-acid mice had normal amounts of the bacterium. 但那些体内没有细菌的老鼠明显也没有了罗伊氏乳杆菌，暴露于丙戊酸的老鼠体内细菌水平正常。

This last result was unexpected, but the team carried on regardless. 最后的这个结果出人意料，但团队还在坚持。

They arranged for between seven and 15 mice of each of the four types to have, starting at the age of three weeks, their drinking water laced with L. reuteri. 他们组了四种类型并安排每一类型中的7到15只老鼠，从三周大的时候就开始饮用掺有罗伊氏乳杆菌的水。

Equivalent numbers of each type continued to be given ordinary water as a control. 作为实验对照，让每种类型中相同数量的老鼠继续饮用普通水。

During the course of the experiment the mice had their faeces collected regularly, so that their bacteria could be tracked. 在实验期间，定期收集老鼠的排泄物，以追踪它们体内的细菌。

And, at the age of seven weeks, they were given two sorts of social tests. 在7周的时候，对它们进行两种社会测试。

The first test involved putting each experimental mouse into a perspex container from which it could go either into a chamber 第一项测试是将每只实验鼠放进一个有机玻璃容器中，它们可以选择钻进其中一个房间中

where there was an empty wire cup or into one where there was a similar cup containing an unfamiliar mouse. 房间中有一个空的线圈杯子，或是进入另一个房间中，这个房间中有一个相似的杯子，但杯中有一只陌生的老鼠。

Subject mice were left in the container for ten minutes and were monitored to see how long they spent with the empty cup and with the other mouse. 实验鼠被留在容器内十分钟并对它们留在空杯中的时间以及和另一只老鼠待在一起的时间进行监测。

The second test placed a mouse in an arena where another, unfamiliar mouse was already present. 第二项测试将一只老鼠放在一个台子上，台中已经站上了另一只陌生的老鼠。

An observer, who did not know which mice were controls and which had been given L. reuteri in their water, 然后由一名观察员（这名观察员不知道哪种老鼠是对照组老鼠，哪只饮用了掺有罗伊氏乳杆菌的水）

then noted how often over the course of ten minutes the two mice touched, sniffed, groomed and crawled on one another. 记下在这十分钟内，这两只老鼠相互触摸、闻、顺毛和爬行的频率。

In both tests, all the mice that had had their water laced with L. reuteri, regardless of how their autism had been induced, 在两项测试中，所有饮用了罗伊氏乳杆菌水的老鼠，不论它们孤独症诱因是什么，

were more sociable than equivalents that had been drinking unlaced water. In the first, they spent twice as much time with the mouse under the wire cup. 均比饮用普通水的同等类更喜欢社交。在第一项测试中，它们在线圈杯中和老鼠相处的时间是同等类的两倍。

In the second, they engaged in many more social interactions with the unfamiliar mouse. 在第二项测试中，它们和另一只不熟悉老鼠的社交互动更多。

The team's initial hypothesis had been that the supplementary L. reuteri were somehow changing the gut flora of the mice exposed to them into something more normal. 团队的初步假设是，添加罗伊氏乳杆菌改变了它们体内的肠道菌群，让它们变得更加正常。

But they weren't. Indeed, L. reuteri proved able to abolish autistic behaviour even in those mice which had guts otherwise devoid of microbes— 但并非如此，罗伊氏乳杆菌确实有消除孤独症行为的可能，即便是那些肠道缺乏细菌的老鼠

as well as in those with valproic-acid-induced autism, which already had normal levels of the bug. 以及那些被丙戊酸诱发孤独症的老鼠，它们已经拥有正常的罗伊氏乳杆菌水平。

That suggests boosting levels of this bacterial species is shaping behaviour all by itself. 这表明促进这种细菌种群的含量是在通过其本身来塑造行为的。

Their next hypothesis was that the bacterium was doing this by interacting somehow with oxytocin, 他们的第二个假设是，细菌通过和催产素的相互作用消除了消除孤独症行为，

a hormone that shapes behaviour and plays a part in the ways in which people and other mammals form social bonds. 催产素是一种塑造行为的激素，以不同的方式在人类和其他哺乳动物的社会联系形成中起作用。

Dr Costa-Mattioli knew from work published in 2013 that spraying oxytocin into the noses of mice with autistic symptoms helps to ameliorate some of those symptoms. Costa-Mattioli博士从2013年发表的一项研究中了解到，往有孤独症症状的老鼠的鼻子喷射催产素可以帮助改善其中一些症状。

Dr Sgritta therefore ran the experiments again, but this time on autistic mice that had had the oxytocin receptors on the relevant neurons disabled by genetic engineering. 因此Sgritta博士再次进行实验，但这一次的实验老鼠是，通过遗传工程将相关神经上的催产素接受器破坏掉。

In these new experiments, the presence of L. reuteriin drinking water had no effect. 在这些新实验中，罗伊氏乳杆菌的存在没有效果。