Mental Well-being: A New York State of Mind

心理健康: 纽约人的精神状态

 

Urban brains behave differently from rural ones

城市人的大脑异于乡村

 

“Hell is a city much like London,” opined Percy Bysshe Shelley in 1819. Modern academics agree. Last year Dutch researchers showed that city dwellers have a 21% higher risk of developing anxiety disorders than do their calmer rural countrymen, and a 39% higher risk of developing mood disorders. But exactly how the inner workings of the urban and rural minds cause this difference has remained obscure – until now. A study just published in Nature by Andreas Meyer-Lindenberg of the University of Heidelberg and his colleagues has used a scanning technique called functional magnetic-resonance imaging (fMRI) to examine the brains of city dwellers and country bumpkins when they are under stress.

 

1819年，波比·雪莱认为“伦敦市更像一个地狱”。现代学者同意这个观点。荷兰研究人员研究表明，城市居民相对稳定的乡村同胞来说，得焦虑症的概率高出21%，得心理障碍疾病的概率高出39%。但是直到现在，城市思想和乡村思想是如何引起这方面差异的确切原因仍旧是不清楚的。最近海德尔堡大学的学者安德烈亚斯·迈耶–林登贝格和他的同事在《自然》杂志上发表了一个研究，该研究使用称为机能性磁共振图像的扫描技术测试了在压力下城市居民和乡村居民的大脑活动情况。

 

In Dr Meyer-Lindenberg’s first experiment, participants lying with their heads in a scanner took math tests that they were doomed to fail (the researchers had designed success rates to be just 25-40%). To make the experience still more humiliating, the team provided negative feedback through headphones, all the while checking participants for indications of stress, such as high blood pressure.

 

在迈耶–林登贝格博士的第一个实验中，参与者躺着头枕在一个扫描器上接受他们注定要失败的数学测验（研究人员仅仅把成功率设为25%—40%）。为了使这活动更加具有羞辱性，研究人员通过耳机给予参与者消极的回答，并一直检测参与者表现出的压力反应，如高血压。

 

The urbanites’ general mental health did not differ from that of their provincial counterparts. However, their brains dealt with the stress imposed by the experimenters in different ways. These differences were noticeable in two regions: the amygdalas and the perigenual anterior cingulate cortex (pACC). The amygdalas are a pair of structures, one in each cerebral hemisphere, that are found deep inside the brain and are responsible for assessing threats and generating the emotion of fear. The pACC is part of the cerebral cortex (again, found in both hemispheres) that regulates the amygdalas.

 

都市人总体的心理健康状况与他们所在地区的其他人没有什么差别。但是，他们应对实验者给予压力的方法不同。这些差别主要在两地地方：杏仁核和扣带皮层部分。杏仁核有一对，大脑左右半球各一个，它在大脑深处，与判断威胁和产生害怕情绪有关。扣带皮层部位是大脑皮层的一部分（也在两个大脑半球），它对杏仁核进行调节。

 

People living in the countryside had the lowest levels of activity in their amygdalas. Those living in towns had higher levels. City dwellers had the highest. Not that surprising, to those of a Shelleyesque disposition. In the case of the pACC, however, what mattered was not where someone was living now, but where he or she was brought up. The more urban a person’s childhood, the more active his pACC, regardless of where he was dwelling at the time of the experiment.

 

生活在乡村的人杏仁核活动水平最低。生活在城镇的人的杏仁核活动水平高些。城市居民杏仁核活动水平最高。对于雪莱式性情的人，这没有什么奇怪的。然而，在扣带皮层部位情况下，重要的不是一个人现在生活在哪，而是他或他在那长大。不管在实验的时候他住在哪，只要一个人的童年时期生活在城市的时间越长，他的扣带皮层部位就越活跃。

 

The amygdalas thus seem to respond to the here-and-now whereas the pACC is programmed early on, and does not react in the same, flexible way as the amygdalas. Second-to-second changes in its activity might, though, be expected to be correlated with changes in the amygdalas, because of its role in regulating them. fMRI allows such correlations to be measured.

 

虽然扣带皮层部位控制着杏仁核，但似乎杏仁核是此时此刻的及时回应，扣带皮层部位并没有像杏仁核那样做出相同，柔性的反应。扣带皮层部位接下来每秒钟活动的变化，也许与杏仁核的变化有关，因为扣带皮层部位控制着杏仁核。 fMRI 显示了这样的测量关系。

 

In the cases of those brought up in the countryside, regardless of where they now live, the correlations were as expected. For those brought up in cities, however, these correlations broke down. The regulatory mechanism of the native urbanite, in other words, seems to be out of kilter. Further evidence, then, for Shelley’s point of view. Moreover, it is also known that the pACC-amygdala link is often out of kilter in schizophrenia, and that schizophrenia is more common among city dwellers than country folk. Dr Meyer-Lindenberg is careful not to claim that his results show the cause of this connection. But they might.

 

在乡村长大的人，不管他们现在住在那，这种相互关系都是不出所料的。然而对于在城市长大的人来说，这种相互关系已经不存在了。换句话说，土生土长的城市人的调控机制似乎脱离了平衡。这是证明雪莱观点的更近一步的证据。而且，众所周知，在精神分裂症病人中，扣带皮层-杏仁核的联系是脱离平衡的，和乡村居民相比，精神分裂症在城市居民中更普遍。迈耶–林登贝格博士很慎重，没有声称他的研究结果表明了这种关联是因果关系。但是，他们也许是因果关系。

 

Dr Meyer-Lindenberg and his team conducted several subsequent experiments to check their findings. They asked participants to complete more maths tests – and also tests in which they mentally rotated an object – while investigators chided them about their performance. The results matched those of the first test. They also studied another group of volunteers, who were given stress-free tasks to complete. These experiments showed no activity in either the amygdalas or the pACC, suggesting that the earlier results were indeed the result of social stress rather than mental exertion.

 

迈耶–林登贝格博士和他的研究组随后进行了几个实验以证他们的结论。他们要求参与者完成更多的数学测验，还有些测试需要参与者在心里转动物体。所有这些都是在研究者斥责参与者表现的情况下进行的。结果和第一次测试的一样。他们也测试了另一组志愿者，让他们完成一些无压力任务。这些实验表明杏仁核或扣带皮层部位没有活动，这表明之前的结果的确是社会压力的结果，而不是心力疲惫的结果。

 

As is usually the case in studies of this sort, the sample size was small (and therefore not as robust as might be desirable) and the result showed an association, rather than a definite, causal relationship. That association is, nevertheless, interesting. Living in cities brings many benefits, but Dr Meyer-Lindenberg’s work suggests that Shelley and his fellow Romantics had at least half a point.

 

这类研究常是如此，样本量小（因此没有我们想要的那个可靠），研究结论表明的仅是一种联系，而不是一个确定的，因果关系。不过，这种联系是令人感兴趣的。生活在城市得到很多好处，但是迈耶–林登贝格博士的研究表明雪莱和他的浪漫主义追随者至少有一半是对的。

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