This left them wondering whether positive emotions and vagal tone drive one another in a virtuous spiral.

这为他们留下了疑念，积极情绪与迷走神经张力是否处于一个良性循环之中，互相促进？

The difference yields an index of vagal tone, and the value of this index is known to be connected with health.

两次心率之差构成迷走神经张力指数。人们都知道该指数与健康程度有关。

Healthy vagal function is reflected in a subtle increase in heart rate while breathing in and a subtle decrease while breathing out.

如果吸气时心率略微增加，呼气时略微下降，则说明迷走神经工作正常。

They measured all of their volunteers' vagal tones at the beginning of the experiment and at its conclusion nine weeks later.

他们在实验开始时测量了所有志愿者的迷走神经张力指数，九周后实验结束时又再次测量。

Dr Fredrickson and Dr Kok discovered that vagal tone increased significantly in people who meditated, and hardly at all in those who did not.

弗雷德里克松博士和可可博士发现，冥想的人的迷走神经张力显著增加，而那些不冥想的人几乎没有任何变化。

A simpler procedure than meditation, namely reflecting at night on the day's social connections, did seem to cause some improvement to their vagal tone.

有一种比冥想简单的方法，即每天晚上对白天的社交活动进行反思，似乎能在一定程度上提高迷走神经张力指数。

Taken as a whole, these findings suggest high vagal tone makes it easier to generate positive emotions and that this, in turn, drives vagal tone still higher.

作为一个整体来看，这些发现意味着，这迷走神经张力指数越高，越容易产生积极情绪；反过来，积极情绪又能促进指数的提升。