But not all changes are visible.

但並非所有改變都是可見的。

In fact, some of the biggest changes happen in her brain.

事實上，某些最大的改變是在腦中發生的。

When a mother sees her newborn for the first time, it's love at first sight, literally.

當一位母親初次見到自己的小孩時，那種感覺基本上就是一見鐘情。

That's because once she gives birth, core regions of her brain's reward network kick in.

那是因為她一旦生產完，腦內獎賞網絡的核心區域就會起作用。

They signal the release of feel-good hormones like dopamine and oxytocin into her blood, which immediately triggers a strong connection of love and devotion to her newborn.

它們會指示像是多巴胺或催產素等讓人感覺良好的賀爾蒙釋放到母親血液中，立即觸發她和新生兒間愛與奉獻的強烈連結。

In fact, studies show that recent mothers have similar levels of oxytocin as romantic couples who are newly in love.

事實上，研究顯示，新手媽媽體內催產素的量與熱戀中的情侶不相上下。

And human moms aren't alone here.

而這不是只會發生在人類母親上的事。

Scientists discovered that rodents got a bigger kick of dopamine from feeding their pups than from receiving injections of cocaine.

科學家發現嚙齒動物在餵養幼鼠時，體內分泌多巴胺所帶來的快樂甚至高於被注射古柯鹼時。

What's more, brain scans reveal that a human mom has a similar experience when she sees her infant smiling.

此外，大腦斷層顯示，一樣的狀況也發生在人類母親看到自己小孩笑的時候。

But it's a different story when her baby is crying.

但當孩子哭的時候，就另當別論了。

Those cries activate a network in the mom's brain known as the emotion regulation network.

那些哭聲會啟動母親腦內的情緒調節網絡。

It includes the prefrontal and cingulate control systems, which help control her emotions.

它包含了可以幫助控制她情緒的前額葉和扣帶控制系統。

And that's important, since it can be easy to lose your temper when you're running on very little sleep and are distressed by the baby's cries.

而那很重要，因為當你每天被寶寶哭聲吵得無暇睡覺、壓力很大時，你會變得很易怒。

And while motherhood can be exhausting, new moms are actually more alert than normal thanks to their brain's salience network.

雖然為人母很辛苦，不過新手媽媽們通常比一般媽媽更有警覺性，這都要多虧腦中的警覺網絡。

Scientists think giving birth activates this network to help a mother detect threats and protect her infant from harm.

科學家認為，生產會觸動這個網絡並幫助母親偵測潛在威脅，保護自己的孩子遠離傷害。

Especially in dangerous situations when that network can help ramp up adrenaline.

特別是在危險情況時，這個網絡會幫助增加腎上腺素。

But on a daily basis, Mom needs to understand her newborn's needs.

但以每日的必要性而言，媽媽得了解新生兒的需求。

To accomplish that, she uses empathy, which comes from her brain's social network.

為了達到這個目標，她會使用腦中社交網絡生成的同理心。

It involves the insula and amygdala, which researchers found became more active when moms looked at photos of their babies in distress compared to neutral photos.

研究人員發現，相較於沒有特別情緒的照片，媽媽看著孩子難過的照片時，她們的腦島和杏仁體都會變得比較活躍。

But it's not just the mom's brain that changes.

但不是只有媽媽的腦袋會有所改變。

Research shows that a dad's brain releases oxytocin when he interacts with his baby, too.

研究顯示，當爸爸在跟自己小孩互動時，腦袋也會釋出催產素。

This is often accompanied by a surge of another hormone, prolactin.

這通常會伴隨另一種荷爾蒙，也就是催乳素的分泌。

It's often called the milk hormone because it triggers the production of breast milk.

它通常被稱為乳激素，因為它會促使母乳的生產。

But men can produce it, too, and researchers have found that dads who frequently played with their babies had higher prolactin levels in their blood than fathers who didn't.

但男性也會製造催乳素，學者也發現常跟自己小孩玩的爸爸，血液中的催乳素比那些不跟小孩玩的爸爸們多。

They were also more responsive to their baby's cries.

他們對於寶寶的哭聲的反應也會比較快。

So, in the end, having a child is a big change.

一言以敝之，有了小孩對父母的人生而言都是個很大的轉變。

Not just for your lifestyle, for your brain, too.

不只是就生活而論，腦內的變化也是一樣。