How much of what you see is a hallucination? - Elizabeth Cox

譯者: Lilian Chiu 審譯者: Helen Chang

An elderly woman named Rosalie was sitting in her nursing home

一位名叫蘿絲莉的老太太， 坐在養老院裡，

when her room suddenly burst to life with twirling fabrics.

她的房間突然間活了起來， 充滿了快速轉動的織物。

Through the elaborate drapings,

透過精密的裝飾，

she could make out animals,

她能認出動物、

children,

孩童，

and costumed characters.

以及穿著戲服的角色。

Rosalie was alarmed, not by the intrusion,

蘿絲莉感到驚恐， 並非因為被這些東西入侵，

but because she knew this entourage was an extremely detailed hallucination.

而是因為她知道周圍的這些事物， 是非常細緻的幻覺。

Her cognitive function was excellent,

她的認知能力很出色，

and she had not taken any medications that might cause hallucinations.

她沒有服用任何會造成幻覺的藥物。

Strangest of all, had a real-life crowd of circus performers burst into her room,

最奇怪的是，就算真的有一群 馬戲團表演者衝入她的房間，

she wouldn’t have been able to see them:

她也無法看到這些人：

she was completely blind.

因為她是全盲的。

Rosalie had developed a condition known as Charles Bonnet Syndrome,

蘿絲莉得到了「邦納症候群」，

in which patients with either impaired vision or total blindness

這種病的病人，不論是視障或全盲，

suddenly hallucinate whole scenes in vivid color.

會突然幻見完整的景象， 充滿鮮明的顏色。

These hallucinations appear suddenly,

這些幻覺都是突然出現的，

and can last for mere minutes or recur for years.

可能持續幾分鐘 或是歷經多年不斷復發。

We still don’t fully understand what causes them to come and go,

我們還無法完全了解是什麼 導致幻覺來來去去，

or why certain patients develop them when others don’t.

或是為什麼某些病人 會有幻覺，某些卻沒有。

We do know from fMRI studies that these hallucinations

我們根據功能性磁振造影的研究

確知這些幻覺會觸發 和視覺使用區域相同的大腦區域，

activate the same brain areas as sight,

areas that are not activated by imagination.

而不是想像所使用的區域。

Many other hallucinations, including smells,

許多其他幻覺，包括嗅覺、

sights,

視覺，

and sounds,

和聽覺，

also involve the same brain areas as real sensory experiences.

涉及的大腦區域也和真實感官體驗 所使用的大腦區域一樣。

Because of this, the cerebral cortex is thought to play a part in hallucinations.

基於這個理由，幻覺被認為 和大腦皮層有部分關係存在。

This thin layer of grey matter covers the entire cerebrum,

這一層薄薄的灰質覆蓋了整個大腦，

with different areas processing information from each of our senses.

來自我們各種感官的資訊， 會有不同的區域來負責處理。

But even in people with completely unimpaired senses,

但對於感官完全沒有障礙的人來說，

the brain constructs the world we perceive from incomplete information.

大腦也是用不完整的資訊 來建構出我們所感知到的世界。

For example, our eyes have blind spots

比如，我們的眼睛會有盲點，

where the optic nerve blocks part of the retina.

視神經會阻擋到部分的視網膜。

When the visual cortex processes light into coherent images,

當視覺皮質把光線 加入到協調連貫的影像中時，

it fills in these blind spots with information from the surrounding area.

它會用周圍區域的資訊 來填補這些盲點。

Occasionally, we might notice a glitch, but most of the time we’re none the wiser.

偶爾，我們會發現有小差錯， 但大部分的時候，我們都不知道。

When the visual cortex is deprived of input from the eyes, even temporarily,

當視覺皮層得不到來自眼睛的 輸入資料時，即使只有一下下，

the brain still tries to create a coherent picture,

大腦仍然會試圖創造出 一個協調連貫的圖像，

but the limits of its abilities become a lot more obvious.

但就能很明顯發現， 它的能力有限。

The full-blown hallucinations of Charles Bonnet Syndrome are one example.

邦納症候群的完整幻覺就是一例。

Because Charles Bonnet Syndrome only occurs in people

因為只有原本視力正常， 後來才失去視力的人，

who had normal vision and then lost their sight,

才會得到邦納症候群，

not those who were born blind,

出生就失明的人就不會，

scientists think the brain uses remembered images

科學家認為， 大腦會使用記得的影像，

to compensate for the lack of new visual input.

來補足新的視覺輸入資料中 缺乏的部分。

And the same is true for other senses.

其他的感官也是一樣的情況。

People with hearing loss often hallucinate music or voices,

有聽力障礙的人， 常常會幻聽到音樂或聲音，

sometimes as elaborate as the cacophony of an entire marching band.

有時，聽到的聲音會複雜到 像有一整個軍樂隊一樣。

In addition to sensory deprivation,

除了感覺喪失之外，

recreational and therapeutic drugs,

娛樂性和治療性藥物、

conditions like epilepsy and narcolepsy,

癲癇與猝睡症等病症，

and psychiatric disorders like schizophrenia,

及精神分裂症等精神疾病，

are a few of the many known causes of hallucinations,

是少數已知的幻覺成因，

and we’re still finding new ones.

且我們還不斷在發現新的成因。

Some of the most notorious hallucinations

有些最惡名昭彰的幻覺

are associated with drugs like LSD and psilocybin.

則是與 LSD 及裸蓋菇素 （都是迷幻藥）等藥物有關。

Their hallmark effects include the sensation that dry objects are wet

它們的招牌效應包括 覺得乾燥的物體是濕的，

and that surfaces are breathing.

以及覺得表面在呼吸。

At higher doses, the visual world can appear to melt,

若劑量更高，視覺世界 有可能會像是融化了一樣，

dissolve into swirls,

分解成漩渦，

or burst into fractal-like patterns.

或是突然變成不規則碎片的圖案。

Evidence suggests these drugs also act on the cerebral cortex.

有證據顯示，這些藥物 也會影響大腦皮層。

But while visual impairment typically only causes visual hallucinations,

雖然視覺障礙通常 只會造成視覺的幻覺，

and hearing loss auditory ones,

失聰通常只會造成聽覺的幻覺，

substances like LSD cause perceptual disturbances across all the senses.

但像 LSD 這類物質卻有可能 造成所有感官的知覺混亂。

That’s likely because they activate receptors in a broad range of brain areas,

很有可能是因為它們會啟動 更多大腦區域的接受器，

including the cortical regions for all the senses.

包括各感官的皮層區域。

LSD and psilocybin both function like serotonin in the brain,

LSD 及裸蓋菇素的功能 都像是大腦中的血清素，

binding directly to one type of serotonin receptor in particular.

特別會直接和一種血清素接受器結合。

While serotonin’s role in the brain is complex and poorly understood,

雖然血清素在大腦中的角色 很複雜且我們不是很了解，

it likely plays an important part in integrating information

但它很有可能在整合資訊上 扮演了重要的角色，

from the eyes,

整合來自眼睛、鼻子、耳朵，

nose,

ears,

and other sensory organs.

和其他感覺器官的資訊。

So one theory is that LSD and psilocybin cause hallucinations

所以，有一種理論是說， LSD 及裸蓋菇素之所以會造成幻覺，

by disrupting the signaling involved in sensory integration.

是因為它們會打斷感官整合 所需要用到的相關訊號。

Hallucinations associated with schizophrenia

和精神分裂症相關的幻覺

may share a similar mechanism with those caused by LSD and psilocybin.

可能與 LSD 及裸蓋菇素 所造成的幻覺有類似的機制。

Patients with schizophrenia

精神分裂症病人

often have elevated levels of serotonin in the brain.

通常大腦中的血清素會比較高。

And antipsychotic drugs relieve symptoms of schizophrenia

而抗精神病藥物 能緩解精神分裂症的症狀，

by blocking the same serotonin receptors LSD and psilocybin bind to.

因為它們能阻擋與 LSD 及裸蓋菇素 結合的那些血清素接受器。

And, in some cases,

在某些案例中，

these drugs can even relieve the hallucinations

這些藥物甚至可以減輕

of patients with Charles Bonnet Syndrome.

邦納症候群病人的幻覺狀況。

We’re still a long way from understanding all the different causes

對於幻覺的各種成因 以及相關聯的機制，

and interconnected mechanisms of hallucinations.

我們還有很多要去了解的。

But it’s clear that hallucinatory experiences

但很清楚的是，幻覺的經歷

are much more closely tied to ordinary perception than we once thought.

和一般感知之間的關係， 遠比我們以前認為的還要密切。

And by studying hallucinations,

透過研究幻覺，

we stand to learn a great deal

我們也能準備好去更了解

about how our brains construct the world we see,

我們的大腦如何建構出 我們所看見、

hear,

聽見、

smell,

and touch.

聞到，

和觸碰到的世界。

As we learn more,

當我們懂更多，

we’ll likely come to appreciate just how subjective and individual

就更有可能會開始欣賞 每個人孤立的感知島嶼世界

each person’s island universe of perception really is.

是有多麼主觀、多麼個人化。