An elderly woman named Rosalie was sitting in her nursing home when her room suddenly burst to life with twirling fabrics. Through the elaborate drapings, she could make out animals, children, and costumed characters. Rosalie was alarmed, not by the intrusion, but because she knew this entourage was an extremely detailed hallucination. Her cognitive function was excellent, and she had not taken any medications that might cause hallucinations. Strangest of all, had a real-life crowd of circus performers burst into her room, she wouldn’t have been able to see them: she was completely blind.
罗萨莉婆婆正坐在养老院的的屋子里, 突然,她的房间充满旋转的图形。 通过精巧的折叠, 她能够制作出动物、 儿童、 和一些穿着戏服的角色。 罗萨莉婆婆感到十分震惊, 并非这些东西突然出现, 而是因为她清楚这些都是 细节极其丰富的幻觉。 她的认知功能一切正常, 也并未服用能够引起幻觉的药物。 最奇怪的在于,若在现实中 有这样一群马戏团演员冲进她的房间, 她也无法看到他们, 因为她彻底失去了视觉。
Rosalie had developed a condition known as Charles Bonnet Syndrome, in which patients with either impaired vision or total blindness suddenly hallucinate whole scenes in vivid color. These hallucinations appear suddenly, and can last for mere minutes or recur for years. We still don’t fully understand what causes them to come and go, or why certain patients develop them when others don’t. We do know from fMRI studies that these hallucinations activate the same brain areas as sight, areas that are not activated by imagination.
罗萨莉患有邦纳症候群。 (Charles Bonnet Syndrome) 患者通常视觉受损或是完全丧失视觉, 眼前却突然出现色彩缤纷的各种幻觉。 这些幻觉的出现很突然, 只会持续几分钟或是在几年内反复发作。 我们仍然不清楚幻觉出现和消失的原因, 也尚不明确 为何只有部分患者出现幻觉。 通过功能性磁共振成像,我们发现 这些幻觉会激活 负责视觉的大脑区域, 而想象力并不会激发该区域。
Many other hallucinations, including smells, sights, and sounds, also involve the same brain areas as real sensory experiences. Because of this, the cerebral cortex is thought to play a part in hallucinations. This thin layer of grey matter covers the entire cerebrum, with different areas processing information from each of our senses. But even in people with completely unimpaired senses, the brain constructs the world we perceive from incomplete information. For example, our eyes have blind spots where the optic nerve blocks part of the retina. When the visual cortex processes light into coherent images, it fills in these blind spots with information from the surrounding area. Occasionally, we might notice a glitch, but most of the time we’re none the wiser.
许多其他的幻觉,包括气味、 视觉、 和声音, 都与负责真实感官的大脑区域相同。 正因为此,大脑皮层被认为与幻觉相关。 这层薄薄的灰质覆盖整个大脑, 不同的区域负责处理 来自各个感官的信息。 但即便对于感官完全正常的人来说, 大脑也是通过不完整的信息 来构建我们所感知的世界。 例如,我们的眼睛有盲点, 此处的光学神经会阻挡部分视网膜。 当视觉中枢处理连续图像的光线时, 它会用周边区域的信息来填充盲点。 有时候,我们或许能发现小错, 但绝大多数情况下我们都不够机敏。
When the visual cortex is deprived of input from the eyes, even temporarily, the brain still tries to create a coherent picture, but the limits of its abilities become a lot more obvious. The full-blown hallucinations of Charles Bonnet Syndrome are one example. Because Charles Bonnet Syndrome only occurs in people who had normal vision and then lost their sight, not those who were born blind, scientists think the brain uses remembered images to compensate for the lack of new visual input. And the same is true for other senses. People with hearing loss often hallucinate music or voices, sometimes as elaborate as the cacophony of an entire marching band.
当视觉中枢不能从眼睛获得信息, 即便只持续短暂的时间, 大脑仍会试图创造出连续的影像。 但这种能力的缺陷则更为明显。 邦纳症候群中 全面爆发的幻觉就是一个例子。 由于这种病症只发生在 后天失明的人身上, 先天失明的人并不会患上该疾病, 科学家认为大脑使用了记忆中的图像, 来弥补新视觉信息的缺失。 对其他感官来说也是同理。 失聪的人们经常幻听到音乐或说话声, 有时声音能够具体到 像是整个军乐队在演奏。
In addition to sensory deprivation, recreational and therapeutic drugs, conditions like epilepsy and narcolepsy, and psychiatric disorders like schizophrenia, are a few of the many known causes of hallucinations, and we’re still finding new ones.
除了感官功能缺失、 服用消遣及治疗性药物之外, 癫痫和发作性睡病等疾病, 以及精神分裂症等精神失调 都是已知的能够导致幻觉的原因。 而我们仍在探索其他原因。
Some of the most notorious hallucinations are associated with drugs like LSD and psilocybin. Their hallmark effects include the sensation that dry objects are wet and that surfaces are breathing. At higher doses, the visual world can appear to melt, dissolve into swirls, or burst into fractal-like patterns. Evidence suggests these drugs also act on the cerebral cortex. But while visual impairment typically only causes visual hallucinations, and hearing loss auditory ones, substances like LSD cause perceptual disturbances across all the senses. That’s likely because they activate receptors in a broad range of brain areas, including the cortical regions for all the senses. LSD and psilocybin both function like serotonin in the brain, binding directly to one type of serotonin receptor in particular. While serotonin’s role in the brain is complex and poorly understood, it likely plays an important part in integrating information from the eyes, nose, ears, and other sensory organs. So one theory is that LSD and psilocybin cause hallucinations by disrupting the signaling involved in sensory integration.
一些众人皆知的幻觉 与LSD和赛洛西宾等致幻剂有很大关系。 它们的典型影响包括让我们 以为干燥物体是湿润的, 物体表面仿佛在呼吸。 剂量加高之后,眼睛看到的世界 则像是融化一般, 一切溶解形成漩涡, 或是变成分形样式。 证据表明这些药物也会影响大脑皮层。 虽然通常视觉受损只会引发视觉上的幻觉, 听力缺失只会导致幻听, 但LSD这类物质 会干扰所有感官的觉知功能。 这很可能是因为 它激发了大脑大片区域的感受器, 包括脑皮质区域的所有感官。 LSD和赛洛西宾 与大脑中的血清素功能相似, 可以与一种特定的 血清素受体直接结合。 虽然血清素在大脑中的功能非常复杂, 且我们对其知之甚少, 它可能是在整合信息方面发挥重要作用, 这些信息来自于眼睛、 鼻子、 耳朵、 以及其他感受器官。 有一种理论认为LSD和赛洛西宾 会通过扰乱感觉统合时的信号 由此导致幻觉。
Hallucinations associated with schizophrenia may share a similar mechanism with those caused by LSD and psilocybin. Patients with schizophrenia often have elevated levels of serotonin in the brain. And antipsychotic drugs relieve symptoms of schizophrenia by blocking the same serotonin receptors LSD and psilocybin bind to. And, in some cases, these drugs can even relieve the hallucinations of patients with Charles Bonnet Syndrome.
与精神分裂症相关的幻觉 与由LSD和赛洛西宾造成的幻觉可能 拥有相同的发病机制。 患有精神分裂症的病人大脑 通常拥有较高的血清素的水平。 治疗精神疾病的药物通过 阻断与LSD和赛洛西宾结合的同种血清素受体 来减轻精神分裂症的症状。 在某些病例中, 这些药物甚至能够减轻 邦纳综合征病人的幻觉。
We’re still a long way from understanding all the different causes and interconnected mechanisms of hallucinations. But it’s clear that hallucinatory experiences are much more closely tied to ordinary perception than we once thought. And by studying hallucinations, we stand to learn a great deal about how our brains construct the world we see, hear, smell, and touch. As we learn more, we’ll likely come to appreciate just how subjective and individual each person’s island universe of perception really is.
在了解幻觉的全部病因 以及相互联系的机制上, 我们仍有很长的路要走。 但现已明确的是 幻觉体验与普通感知的关系 比我们想象的更近。 通过研究幻觉, 我们能够更多地了解 我们的大脑如何通过所看、 所听、 所闻、 所触来构建世界。 随着我们不断研究, 我们将能够欣赏每个人的感觉世界 是多么的主观和独特。