研究稱親近大自然有助于改善情緒

A walk in the park may soothe the mind and, in the process, change the workings of our brains in ways that improve our mental health, according to an interesting new study of the physical effects on the brain of visiting nature.

根據(jù)一項以親近自然對大腦的生理影響為主題的有趣的新研究，去公園散步或許能放松心神，在此期間讓大腦的運作發(fā)生有助于改善精神健康狀況的變化。

Most of us today live in cities and spend far less time outside in green, natural spaces than people did several generations ago.

如今，我們大多數(shù)人都生活在城市中，比起幾代以前的人，我們與綠意盎然的自然空間相處的時間大大減少了。

City dwellers also have a higher risk for anxiety, depression and other mental illnesses than people living outside urban centers, studies show.

還有研究顯示，城市居民感到焦慮、抑郁或出現(xiàn)其他精神問題的風險，高于居住在城市中心以外的人。

These developments seem to be linked to some extent, according to a growing body of research. Various studies have found that urban dwellers with little access to green spaces have a higher incidence of psychological problems than people living near parks and that city dwellers who visit natural environments have lower levels of stress hormones immediately afterward than people who have not recently been outside.

越來越多的研究表明，這些新情況之間似乎存在某種程度的關聯(lián)。根據(jù)多項研究，基本不接觸綠地的城市居民遭遇心理問題的幾率，比住在公園附近的人要高;而城市居民在親近大自然之后，體內壓力荷爾蒙的水平立即就會低于近來沒走出過家門的人。

But just how a visit to a park or other green space might alter mood has been unclear. Does experiencing nature actually change our brains in some way that affects our emotional health?

但目前還不清楚，逛公園或探訪其他綠色空間可能如何改變人的情緒。親近自然真能給我們的大腦帶來某種會影響精神健康的改變嗎?

That possibility intrigued Gregory Bratman, a graduate student at the Emmett Interdisciplinary Program in Environment and Resources at Stanford University, who has been studying the psychological effects of urban living. In an earlier study published last month, he and his colleagues found that volunteers who walked briefly through a lush, green portion of the Stanford campus were more attentive and happier afterward than volunteers who strolled for the same amount of time near heavy traffic.

這種可能性激起了斯坦福大學(Stanford University)埃米特環(huán)境與資源跨學科項目(Emmett Interdisciplinary Program in Environment and Resources)研究生格雷戈里·布拉特曼(Gregory Bratman)的興趣，他一直在研究城市生活對心理的影響。在早前的一項研究中，他和同事們發(fā)現(xiàn)，志愿者短暫穿行于斯坦福校園內一片郁郁蔥蔥的綠地之中后，比那些花同樣長的時間在交通繁忙處散了步的志愿者更專注，也更快樂，相關研究結果已于上月發(fā)表。

But that study did not examine the neurological mechanisms that might underlie the effects of being outside in nature. 但該研究并未考察或許在外出親近自然的影響背后發(fā)揮作用的神經(jīng)機制。

So for the new study, which was published last week in Proceedings of the National Academy of Sciences, Mr. Bratman and his collaborators decided to closely scrutinize what effect a walk might have on a person’s tendency to brood.

因此，布拉特曼及其同事決定在新研究中密切審視散步會對一個人沉溺于憂思的傾向產(chǎn)生什么影響，其研究成果于上周發(fā)表在了《國家科學院院刊》(Proceedings of the National Academy of Sciences)上。

Brooding, which is known among cognitive scientists as morbid rumination, is a mental state familiar to most of us, in which we can’t seem to stop chewing over the ways in which things are wrong with ourselves and our lives. This broken-record fretting is not healthy or helpful. It can be a precursor to depression and is disproportionately common among city dwellers compared with people living outside urban areas, studies show.

沉溺于憂思被認知科學家稱為病態(tài)的反芻思考，是我們大多數(shù)人都很熟悉的一種心理狀態(tài)，當我們陷入其中時，會情不自禁地反復琢磨我們自己以及我們的生活怎么就出了問題。這種過分的焦躁是不健康的，也于事無補。有研究顯示，它可能是抑郁的先兆;比起住在城市地區(qū)以外的人，城市居民出現(xiàn)這種情況的比例奇高。

Perhaps most interesting for the purposes of Mr. Bratman and his colleagues, however, such rumination also is strongly associated with increased activity in a portion of the brain known as the subgenual prefrontal cortex.

不過，就布拉特曼及其同事的目的而言，最有趣的或許是：這種反芻思考與腦內膝下區(qū)前額葉皮層活動增加之間有很高的關聯(lián)度。

If the researchers could track activity in that part of the brain before and after people visited nature, Mr. Bratman realized, they would have a better idea about whether and to what extent nature changes people’s minds.

布拉特曼意識到，如果研究人員能在人們親近自然之前和之后追蹤其腦內這一區(qū)域的活動，就可以更好地了解自然能否改變，或者能在多大程度上改變人類的情緒。

Mr. Bratman and his colleagues first gathered 38 healthy, adult city dwellers and asked them to complete a questionnaire to determine their normal level of morbid rumination.

布拉特曼及其同事先是找到38名健康且已成年的城市居民，并讓他們完成一份問卷，以確定通常情況下他們的病態(tài)反芻思考指數(shù)。

The researchers also checked for brain activity in each volunteer’s subgenual prefrontal cortex, using scans that track blood flow through the brain. Greater blood flow to parts of the brain usually signals more activity in those areas.

研究人員還通過以掃描儀追蹤每名志愿者腦部的血流，檢查了其膝下區(qū)前額葉皮層的活動。通常而言，腦部哪個區(qū)域的血流量增大，就代表著那個區(qū)域的活動增多。

Then the scientists randomly assigned half of the volunteers to walk for 90 minutes through a leafy, quiet, parklike portion of the Stanford campus or next to a loud, hectic, multi-lane highway in Palo Alto. The volunteers were not allowed to have companions or listen to music. They were allowed to walk at their own pace.

隨后，科學家們隨機分派半數(shù)志愿者在斯坦福校園內一個綠蔭環(huán)繞、安安靜靜，仿佛公園般的去處散步90分鐘，另外半數(shù)則被分派到帕羅奧圖的一條嘈雜、繁忙的多車道高速公路邊，走了同樣長的時間。志愿者不得結伴而行或聽音樂，但可以自行控制速度。

Immediately after completing their walks, the volunteers returned to the lab and repeated both the questionnaire and the brain scan.

散步一結束，志愿者便返回實驗室，再一次填寫問卷、做腦部掃描。

As might have been expected, walking along the highway had not soothed people’s minds. Blood flow to their subgenual prefrontal cortex was still high and their broodiness scores were unchanged.

不出所料，在高速公路邊散步?jīng)]有對人們的情緒起到撫慰作用。膝下區(qū)前額葉皮層的血流量仍然很高，他們的憂思指數(shù)也沒變。

But the volunteers who had strolled along the quiet, tree-lined paths showed slight but meaningful improvements in their mental health, according to their scores on the questionnaire. They were not dwelling on the negative aspects of their lives as much as they had been before the walk.

但問卷上的分數(shù)顯示，那些沿著綠樹成蔭的靜謐小路散步的志愿者，精神健康狀況出現(xiàn)了雖然不大但卻很有意義的改善。他們對生活的消極面的關注程度比出去散步前要低。

They also had less blood flow to the subgenual prefrontal cortex. That portion of their brains were quieter.

膝下區(qū)前額葉皮層的血流量也下降了。他們腦部的那一區(qū)域更為平靜。

These results “strongly suggest that getting out into natural environments” could be an easy and almost immediate way to improve moods for city dwellers, Mr. Bratman said.

布拉特曼說，這些結果“強烈暗示，外出親近大自然”是改善城市居民情緒的一個簡單而又近乎立竿見影的方法。