But with the current pornography epidemic as some call it.

然而最近 A 片盛行簡直泛濫成災。

One has to wonder how exactly this may effect our desires and perception of sexuality. Moreover, how does it affect our sex lives.

令人好奇 A 片何以影響我們對性的慾望和看法，又是如何影響我們的性生活呢？

Pornography constitutes about twenty five percent of all search engine requests, and is the fourth most common reason people give for going on the internet.

在所有搜尋查詢中 A 片約佔 1/4，同時名列上網原因第四名。

And well, it may seem to simply facilitate an instinctual sexual response linked to millions of years of evolution.

對性的本能反應似乎符合百萬年演化規則。

The truth is pornography has dynamically changed over time ultimately molding our tastes and desires.

事實是，A 片隨著時間改變最終形塑我們對性的偏好與慾望。

The not so shocking truth is that pornography has profound consequences for the brain and acts in many ways like a drug.

不意外的是 A 片對大腦有深遠的影響，在很多方面 A 片的作用就像藥物。

With prolonged exposure your tolerance is increased and many often find themselves addicted.

長期接觸後，你對性的胃口會變大，甚至上癮。

Though it is not a physical substance, it leads to the same general loss of control, the compulsiveness to seek out the activity despite negative consequences and withdrawal when it goes away.

雖然 A 片不像藥物，但同樣會讓你失去控制，讓你想看更多，即使帶來壞的影響也在所不惜，無法取得時甚至出現戒斷症狀。

Much like that of gambling or running for example.

就像賭博和慢跑。

The issue is that continued exposure can cause long-term or even lifelong neuro-plastic change in the brain.

問題是持續暴露，大腦神經連結會發生長期或終生的改變。

Dopamine is released as a reward whenever we accomplish something, whether it be eating to sustain life or sexual activity to produce future life.

當我們完成某事時，大腦會釋放出多巴胺，不論是進食維繫生命，或從事性行為繁衍後代都一樣。

And this dopamine consolidates neural connections in order to drive us to perform the same activity in the future.

多巴胺會強化神經連結 ，驅使我們去做更多同樣的事。

In other words, it alters and forms the brain cells to motivate certain actions.

換句話說，它改變並形塑大腦細胞，令我們更容易去做某些行為。

It rewires your brain.

它重新連結了我們的大腦。

The national institutes of health measure drug addictiveness by testing rats.

美國衛生研究院 ，測量白老鼠藥物上癮的程度。

The rat is trained to press a button in order to get a drug, and the harder it works indicates how addictive the substance is.

這些老鼠學會按按鈕取得藥物，按得越大力代表上癮程度越高。

It turns out that the more addictive a drug is the more dopamine we see released.

結果發現，更容易上癮的藥會令老鼠大腦分泌更多的多巴胺。

And while there is unfortunately no rat porn that we can give to them, we do know that dopamine is also released during sexual excitement which pornography plays right into.

雖然老鼠 A 片並不存在，無法拿給這些老鼠看，可確定的是 A 片所引發的性興奮會誘使大腦分泌多巴胺。

The more time you spend doing it, the more dopamine gets released which reinforces the behavior and makes you not only desire it in the future but require it.

觀看的時間越久，會釋放出越多的多巴胺，因此強化該行為，令你往後不只渴求，甚至有賴於它。

And as you begin to imagine these images away from the computer or while having sex, they become reinforced.

當你不在電腦前或正從事性行為，你開始重溫並不斷強化這些畫面。

Furthermore each orgasm releases even more dopamine which consolidates the connections made during the session.

每次性高潮時甚至分泌更多的多巴胺，不斷鞏固這種連結。

It's a feedback loop that becomes harder to escape and just like a drug your tolerance for visual stimulation has now compounded, making it more difficult to be turned on by reality.

形成一種回饋迴路，令你更難逃脫 ，就像藥物對於視覺刺激要求越來越高，現實的一切更難激發性慾。

Pornography addiction can often lead to finding your mate less attractive, the good news is it doesn't have to be permanent.

A 片上癮可能會讓你對另一半性趣缺缺，但還好這不是永久現象。

Usually when people understand the mechanism and realize it's affecting their relationships, they can stop.

一旦人們了解這種機制運作，察覺到這會傷害親密關係，他們便會停止。

The brain is often described as a use it or lose it system because the neural connections you stimulate grow stronger and desire to be activated while the ones you ignore become weakened.

大腦系統經常被描述成「用進廢退」，因為受刺激的神經連結會因此強化、渴求激發，反之，不受刺激的連結則會弱化。

Much like your muscles which if sitting still all day itch for activity but after prolonged non-use they become complacent.

就像肌肉，久坐一天你會想起來動一動，但時間久了都完全不用，肌肉便不再發達。

Luckily, because of this "use it or lose it" brain, the same neuro-plastic system that proliferate these habits can also be used to acquire healthier ones.

幸好，因為大腦用進廢退，神經可塑性機制培養壞習慣，也能夠重建好習慣。

Got a burning question you want answered? Asking it in the comments or on facebook and twitter.

想破頭也想知答案？ 在留言區或是在 FB 及 Twitter 上提問。

And subscribe for more weekly science videos.

記得訂閱頻道觀賞更多每週科學影片。