菲奧娜·麥克雷

New mothers often grumble that their brain has turned into mush. But having a baby may actually make you brighter， a study has found.

Research shows that a woman’s grey matter grows in the weeks and months after she has given birth.

And it’s the most doting mothers who experience the biggest burst of brain cells2.

It is thought that the hormonal changes associated with having a baby ‘supercharge3’ the brain， helping prepare women for the challenges ahead.

And the memory lapses that plague new mothers may be explained by a simpler cause—sleep deprivation4.

The finding， from a small study published by the American Psychological Association， contradicts the long-held notion that motherhood addles a woman’s brain.

Neuroscientists from the respected Yale University in the U.S. scanned the brains of 19 new mothers in the weeks after they had given birth.

The results showed that the amount of grey matter—brain cells that crunch information—had increased by a small but significant amount by the time the women were three to four months into motherhood.

Such changes usually only occur after intense periods of learning or a brain injury or illness.

The areas that grew involve motivation， reasoning， judgement， the processing of emotions and feelings of satisfaction， and are key to the mother-child relationship.

Expansion in the brain’s ‘motivation area’， said the researchers， could lead to more nurturing， which would help babies survive and thrive physically， emotionally and cognitively.

The mothers who gushed most about5 their newborns tended to experience the biggest amounts of growth， the journal Behavioral Neuroscience reports.

It is unclear to what extent the changes are due to rises in hormones such as oestrogen6 and oxytocin7 that occur when a woman gives birth， and how much they are caused by chemical changes brought on by cuddling and playing with their babies.

Studies of adoptive mothers could help separate the two.

Siobhan Freegard， founder of the Netmums website， said that ‘supercharging’ made sense.

She added： “Nature has an amazing way of giving us things that we need. Having a baby is a momentous occasion， so it is not surprising the brain gets that little bit extra to equip us for the challenge.”

She suggested that any ‘baby brain’ memory lapses could be due to changing priorities， with the newborn being deemed more important than most other matters.

The results of the study echo research which concluded that， contrary to popular belief， pregnancy does nothing to dim brainpower.

Professor Helen Christensen， of the Australian National University in Canberra， showed that women did as well on tests of memory and logic when pregnant as they had in previous years.

She said： “It really leaves the question open as to why women—and often their partners—think they have poor memories， when the best evidence we have is that they don’t.

“Perhaps women notice minor lapses in mental ability and then attribute it to being pregnant because that is the most significant thing in their mind at the time.

“Or sleep deprivation could mask the positive cognitive effect.”

新生兒母親經(jīng)常抱怨自己的大腦變得糊里糊涂。但研究發(fā)現(xiàn)，分娩實際上可能會讓女性更聰明。

研究表明，分娩后的數(shù)周到數(shù)月內(nèi)，女性大腦中的灰質(zhì)會增多。

并且，最寵愛孩子的母親，腦細胞暴增程度最大。

有人認為，激素變化與分娩有關(guān)，并會給大腦“增加能量”，幫助女性為未來的挑戰(zhàn)做準備。

而新生兒母親為記憶衰退所困擾，可能有一個更簡單的原因——睡眠不足。

這一發(fā)現(xiàn)來自美國心理學會公布的一項小型研究，與長期以來認為做母親會讓女性頭腦糊涂的觀念相矛盾。

美國名校耶魯大學的神經(jīng)學家在19位新生兒母親分娩后的數(shù)周內(nèi)，掃描了她們的大腦。

結(jié)果顯示，女性分娩后3到4個月時，灰質(zhì)——處理信息的腦細胞——數(shù)量增加了，增加數(shù)量雖小但意義重大。

這種變化通常只發(fā)生在緊張的學習期、腦損傷或疾病之后。

擴大的大腦區(qū)域與動機、推理、判斷、情緒處理和滿足感有關(guān)，是母親與孩子發(fā)展關(guān)系的關(guān)鍵。

研究人員說母親大腦“動機區(qū)域”的擴大可以讓嬰兒得到更多撫育，這將有助于嬰兒生存，并在身心和認知上迅速成長。

據(jù)《行為神經(jīng)科學》雜志報道，最愛夸贊新生兒的母親，腦細胞增長數(shù)目最多。

這些變化多大程度上由女性分娩時雌激素和催產(chǎn)素等激素的上升而引起，多大程度上由摟抱嬰兒和陪嬰兒玩耍帶來的化學變化而引起，這點卻不清楚。

關(guān)于養(yǎng)母的研究有助于區(qū)分這兩者。

“媽媽網(wǎng)”創(chuàng)始人茜奧班·弗里加德表示，“增加能量”是有道理的。

她補充道：“大自然以令人驚奇的方式提供我們需要的東西。 生孩子是個重要時刻，所以大腦額外增大一點點，讓我們應(yīng)對挑戰(zhàn)，這不奇怪?！?/p>

茜奧班認為，由于母親視新生兒比其他大多數(shù)事情更重要，任何“嬰兒腦”式記憶衰退都可能是優(yōu)先事項變化的結(jié)果。

該研究的結(jié)果與一項調(diào)查相呼應(yīng)，該項調(diào)查認為，與普遍看法相反，懷孕對智力減退毫無影響。

堪培拉市澳大利亞國立大學的海倫·克里斯滕森教授表示，女性懷孕時，記憶力和邏輯測試做得和過去幾年一樣好。

她說：“這確實讓人存疑， 為什么女性及其伴侶經(jīng)常認為她們的記憶力很差， 而我們有最佳證據(jù)證明她們不是這樣。

“也許女性會注意到心智能力的輕微衰退，然后將其歸因于妊娠，因為這是當時她們腦中最重要的事情。

“或者睡眠不足可能掩蓋了積極的認知效應(yīng)?！?/p>

（譯者為“《英語世界》杯”翻譯大賽獲獎選手）