How memories form and how we lose them - Catharine Young

譯者: Helen Chang 審譯者: 柳 佑昇

Think back to a really vivid memory.

試著回想你最鮮明的記憶。

Got it?

想到了嗎？

Okay, now try to remember what you had for lunch three weeks ago.

好，回想三星期前你吃了什麼午餐。

That second memory probably isn't as strong,

第二個記憶可能沒第一個那麼強烈，

but why not?

但為什麼呢？

Why do we remember some things, and not others?

為什麼我們記得一些事， 卻忘了另一些呢？

And why do memories eventually fade?

為什麼記憶最後會消逝呢？

Let's look at how memories form in the first place.

我們先看看最初記憶是如何成形的。

When you experience something, like dialing a phone number,

當你做某件事，如撥電話，

the experience is converted into a pulse of electrical energy

這經歷轉變成電脈衝能量

that zips along a network of neurons.

在神經元網絡內流動。

Information first lands in short term memory,

訊息會先在短暫記憶區內停留，

where it's available from anywhere from a few seconds

停留數秒至數分鐘；

to a couple of minutes.

It's then transferred to long-term memory through areas such as the hippocampus,

再經由如海馬迴這樣的區域 傳送到長期記憶區，

and finally to several storage regions across the brain.

最後到達腦內的數個儲存區域。

Neurons throughout the brain communicate at dedicated sites

腦內各處的神經元

called synapses

透過稱為突觸的特定地點

using specialized neurotransmitters.

利用專門的神經遞質彼此聯絡。

If two neurons communicate repeatedly, a remarkable thing happens:

如果一對神經元重覆互聯， 就會有精彩的結果：

the efficiency of communication between them increases.

它們之間的通訊效率提升。

This process, called long term potentiation,

這個流程稱為長期增強作用，

is considered to be a mechanism by which memories are stored long-term,

被視為是長期記憶的儲存機制。

but how do some memories get lost?

但是，為何有些記憶消逝了呢？

Age is one factor.

老化是一個因素。

As we get older, synapses begin to falter and weaken,

隨著年長，突觸開始萎縮變弱，

affecting how easily we can retrieve memories.

增加喚醒記憶的難度。

Scientists have several theories about what's behind this deterioration,

科學家有數個腦退化原因的理論：

from actual brain shrinkage,

自腦部萎縮－

the hippocampus loses 5% of its neurons every decade

海馬迴每十年損失5%的神經元，

for a total loss of 20% by the time you're 80 years old

到80歲時，總共損失20%；

to the drop in the production of neurotransmitters,

至神經傳遞質的產出減少－

like acetylcholine, which is vital to learning and memory.

像是乙醯膽鹼 這種學習和記憶不可或缺的元素。

These changes seem to affect how people retrieve stored information.

這個變化似乎影響人們 喚醒儲存訊息的效率。

Age also affects our memory-making abilities.

老化也降低記憶形成的能力。

Memories are encoded most strongly when we're paying attention,

最強的記憶編碼發生在我們留意，

when we're deeply engaged, and when information is meaningful to us.

被深深地吸引， 和訊息對我們有意義時。

Mental and physical health problems, which tend to increase as we age,

隨著老化，增多的身心健康問題

interfere with our ability to pay attention,

會干擾專注的能力，

and thus act as memory thieves.

就像盜走記憶的小偷。

Another leading cause of memory problems is chronic stress.

另一個記憶問題的主因是長期壓力。

When we're constantly overloaded with work and personal responsibilites,

當我們於公、於私 持續背負重責和工作量時，

our bodies are on hyperalert.

身體處於非常警覺狀態。

This response has evolved from the physiological mechanism

這是心理機制進化的反應，

designed to make sure we can survive in a crisis.

目的是使我們能夠 應付危機，生存下來。

Stress chemicals help mobilize energy and increase alertness.

壓力化學物質有助 調動能量和增加警覺性。

However, with chronic stress our bodies become flooded with these chemicals,

但是，身體會因為長期壓力 而充滿這些化學物質，

resulting in a loss of brain cells and an inability to form new ones,

導致損失且無法新生腦細胞，

which affects our ability to retain new information.

進一步影響保有記憶的能力。

Depression is another culprit.

憂鬱是另一個罪魁禍首。

People who are depressed are 40% more likely to develop memory problems.

憂鬱的人生出記憶問題的機率 比一般人高出40%。

Low levels of serotonin,

連接覺醒的神經傳遞質－ 血清素－含量過低，

a neurotransmitter connected to arousal,

may make depressed individuals less attentive to new information.

可能使憂鬱的人較不留心新訊息。

Dwelling on sad events in the past, another symptom of depression,

另一個憂鬱的症狀 是沉浸在過去的悲傷事件中，

makes it difficult to pay attention to the present,

難以對眼前的事物感興趣，

affecting the ability to store short-term memories.

因此影響短期記憶的儲存能力。

Isolation, which is tied to depression, is another memory thief.

跟憂鬱緊緊相關的孤立 是另一個竊取記憶的賊。

A study by the Harvard School of Public Health

哈佛大學公共健康部的研究發現

found that older people with high levels of social integration

與社會互動較多的長者，

had a slower rate of memory decline over a six-year period.

在六年間的記憶退化較緩慢。

The exact reason remains unclear,

雖然還不清楚確切的原因，

but experts suspect that

但是專家推測

social interaction gives our brain a mental workout.

社會互動會活動大腦。

Just like muscle strength,

就像肌肉強度，

we have to use our brain or risk losing it.

我們必須用腦，否則它就會退化。

But don't despair.

但是不要絕望。

There are several steps you can take

有幾個可採取的步驟

to aid your brain in preserving your memories.

可以幫助大腦保持記憶。

Make sure you keep physically active.

一定要活絡筋骨－

Increased blood flow to the brain is helpful.

增加血液流動到大腦是有益的。

And eat well.

均衡飲食－

Your brain needs all the right nutrients to keep functioning correctly.

大腦需要有所有的好營養 才能正常運作。

And finally, give your brain a workout.

最後，動動腦－

Exposing your brain to challenges, like learning a new language,

給大腦一些挑戰，例如

學習新語言是保衛記憶完整 的最好方式之一。

is one of the best defenses for keeping your memories intact.