[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.67,0:00:10.02,Default,,0000,0000,0000,,An elderly woman named Rosalie \Nwas sitting in her nursing home
Dialogue: 0,0:00:10.02,0:00:14.29,Default,,0000,0000,0000,,when her room suddenly burst \Nto life with twirling fabrics.
Dialogue: 0,0:00:14.29,0:00:16.02,Default,,0000,0000,0000,,Through the elaborate drapings,
Dialogue: 0,0:00:16.02,0:00:17.46,Default,,0000,0000,0000,,she could make out animals,
Dialogue: 0,0:00:17.46,0:00:18.21,Default,,0000,0000,0000,,children,
Dialogue: 0,0:00:18.21,0:00:20.04,Default,,0000,0000,0000,,and costumed characters.
Dialogue: 0,0:00:20.04,0:00:22.71,Default,,0000,0000,0000,,Rosalie was alarmed,\Nnot by the intrusion,
Dialogue: 0,0:00:22.71,0:00:27.80,Default,,0000,0000,0000,,but because she knew this entourage \Nwas an extremely detailed hallucination.
Dialogue: 0,0:00:27.80,0:00:30.16,Default,,0000,0000,0000,,Her cognitive function was excellent,
Dialogue: 0,0:00:30.16,0:00:34.64,Default,,0000,0000,0000,,and she had not taken any medications \Nthat might cause hallucinations.
Dialogue: 0,0:00:34.64,0:00:39.66,Default,,0000,0000,0000,,Strangest of all, had a real-life crowd \Nof circus performers burst into her room,
Dialogue: 0,0:00:39.66,0:00:41.74,Default,,0000,0000,0000,,she wouldn’t have been able to see them:
Dialogue: 0,0:00:41.74,0:00:44.25,Default,,0000,0000,0000,,she was completely blind.
Dialogue: 0,0:00:44.25,0:00:48.44,Default,,0000,0000,0000,,Rosalie had developed a condition known \Nas Charles Bonnet Syndrome,
Dialogue: 0,0:00:48.44,0:00:52.13,Default,,0000,0000,0000,,in which patients with either impaired \Nvision or total blindness
Dialogue: 0,0:00:52.13,0:00:55.54,Default,,0000,0000,0000,,suddenly hallucinate whole scenes \Nin vivid color.
Dialogue: 0,0:00:55.54,0:00:57.99,Default,,0000,0000,0000,,These hallucinations appear suddenly,
Dialogue: 0,0:00:57.99,0:01:02.11,Default,,0000,0000,0000,,and can last for mere minutes \Nor recur for years.
Dialogue: 0,0:01:02.11,0:01:05.62,Default,,0000,0000,0000,,We still don’t fully understand \Nwhat causes them to come and go,
Dialogue: 0,0:01:05.62,0:01:08.78,Default,,0000,0000,0000,,or why certain patients develop them \Nwhen others don’t.
Dialogue: 0,0:01:08.78,0:01:13.01,Default,,0000,0000,0000,,We do know from fMRI studies \Nthat these hallucinations
Dialogue: 0,0:01:13.01,0:01:15.52,Default,,0000,0000,0000,,activate the same brain areas as sight,
Dialogue: 0,0:01:15.52,0:01:20.02,Default,,0000,0000,0000,,areas that are not activated \Nby imagination.
Dialogue: 0,0:01:20.02,0:01:22.90,Default,,0000,0000,0000,,Many other hallucinations, \Nincluding smells,
Dialogue: 0,0:01:22.90,0:01:23.78,Default,,0000,0000,0000,,sights,
Dialogue: 0,0:01:23.78,0:01:24.76,Default,,0000,0000,0000,,and sounds,
Dialogue: 0,0:01:24.76,0:01:29.43,Default,,0000,0000,0000,,also involve the same brain areas \Nas real sensory experiences.
Dialogue: 0,0:01:29.43,0:01:35.63,Default,,0000,0000,0000,,Because of this, the cerebral cortex is\Nthought to play a part in hallucinations.
Dialogue: 0,0:01:35.63,0:01:39.53,Default,,0000,0000,0000,,This thin layer of grey matter \Ncovers the entire cerebrum,
Dialogue: 0,0:01:39.53,0:01:44.17,Default,,0000,0000,0000,,with different areas processing \Ninformation from each of our senses.
Dialogue: 0,0:01:44.17,0:01:47.11,Default,,0000,0000,0000,,But even in people\Nwith completely unimpaired senses,
Dialogue: 0,0:01:47.11,0:01:51.84,Default,,0000,0000,0000,,the brain constructs the world we perceive\Nfrom incomplete information.
Dialogue: 0,0:01:51.84,0:01:54.13,Default,,0000,0000,0000,,For example, our eyes have blind spots
Dialogue: 0,0:01:54.13,0:01:57.09,Default,,0000,0000,0000,,where the optic nerve \Nblocks part of the retina.
Dialogue: 0,0:01:57.09,0:02:00.89,Default,,0000,0000,0000,,When the visual cortex processes light \Ninto coherent images,
Dialogue: 0,0:02:00.89,0:02:05.53,Default,,0000,0000,0000,,it fills in these blind spots with \Ninformation from the surrounding area.
Dialogue: 0,0:02:05.53,0:02:10.46,Default,,0000,0000,0000,,Occasionally, we might notice a glitch,\Nbut most of the time we’re none the wiser.
Dialogue: 0,0:02:10.46,0:02:15.68,Default,,0000,0000,0000,,When the visual cortex is deprived \Nof input from the eyes, even temporarily,
Dialogue: 0,0:02:15.68,0:02:18.81,Default,,0000,0000,0000,,the brain still tries \Nto create a coherent picture,
Dialogue: 0,0:02:18.81,0:02:22.95,Default,,0000,0000,0000,,but the limits of its abilities \Nbecome a lot more obvious.
Dialogue: 0,0:02:22.95,0:02:27.97,Default,,0000,0000,0000,,The full-blown hallucinations of\NCharles Bonnet Syndrome are one example.
Dialogue: 0,0:02:27.97,0:02:30.60,Default,,0000,0000,0000,,Because Charles Bonnet Syndrome \Nonly occurs in people
Dialogue: 0,0:02:30.60,0:02:33.57,Default,,0000,0000,0000,,who had normal vision \Nand then lost their sight,
Dialogue: 0,0:02:33.57,0:02:35.31,Default,,0000,0000,0000,,not those who were born blind,
Dialogue: 0,0:02:35.31,0:02:38.30,Default,,0000,0000,0000,,scientists think the brain uses\Nremembered images
Dialogue: 0,0:02:38.30,0:02:41.92,Default,,0000,0000,0000,,to compensate for \Nthe lack of new visual input.
Dialogue: 0,0:02:41.92,0:02:44.07,Default,,0000,0000,0000,,And the same is true for other senses.
Dialogue: 0,0:02:44.07,0:02:47.98,Default,,0000,0000,0000,,People with hearing loss \Noften hallucinate music or voices,
Dialogue: 0,0:02:47.98,0:02:52.93,Default,,0000,0000,0000,,sometimes as elaborate as the cacophony \Nof an entire marching band.
Dialogue: 0,0:02:52.93,0:02:55.66,Default,,0000,0000,0000,,In addition to sensory deprivation,
Dialogue: 0,0:02:55.66,0:02:57.94,Default,,0000,0000,0000,,recreational and therapeutic drugs,
Dialogue: 0,0:02:57.94,0:03:00.86,Default,,0000,0000,0000,,conditions like epilepsy and narcolepsy,
Dialogue: 0,0:03:00.86,0:03:03.64,Default,,0000,0000,0000,,and psychiatric disorders \Nlike schizophrenia,
Dialogue: 0,0:03:03.64,0:03:06.100,Default,,0000,0000,0000,,are a few of the many known causes \Nof hallucinations,
Dialogue: 0,0:03:06.100,0:03:09.23,Default,,0000,0000,0000,,and we’re still finding new ones.
Dialogue: 0,0:03:09.23,0:03:11.62,Default,,0000,0000,0000,,Some of the most notorious hallucinations
Dialogue: 0,0:03:11.62,0:03:15.47,Default,,0000,0000,0000,,are associated with drugs \Nlike LSD and psilocybin.
Dialogue: 0,0:03:15.47,0:03:20.40,Default,,0000,0000,0000,,Their hallmark effects include \Nthe sensation that dry objects are wet
Dialogue: 0,0:03:20.40,0:03:23.07,Default,,0000,0000,0000,,and that surfaces are breathing.
Dialogue: 0,0:03:23.07,0:03:26.98,Default,,0000,0000,0000,,At higher doses, the visual world \Ncan appear to melt,
Dialogue: 0,0:03:26.98,0:03:28.32,Default,,0000,0000,0000,,dissolve into swirls,
Dialogue: 0,0:03:28.32,0:03:31.34,Default,,0000,0000,0000,,or burst into fractal-like patterns.
Dialogue: 0,0:03:31.34,0:03:35.52,Default,,0000,0000,0000,,Evidence suggests these drugs also \Nact on the cerebral cortex.
Dialogue: 0,0:03:35.52,0:03:39.90,Default,,0000,0000,0000,,But while visual impairment typically \Nonly causes visual hallucinations,
Dialogue: 0,0:03:39.90,0:03:41.79,Default,,0000,0000,0000,,and hearing loss auditory ones,
Dialogue: 0,0:03:41.79,0:03:48.39,Default,,0000,0000,0000,,substances like LSD cause perceptual\Ndisturbances across all the senses.
Dialogue: 0,0:03:48.39,0:03:53.12,Default,,0000,0000,0000,,That’s likely because they activate \Nreceptors in a broad range of brain areas,
Dialogue: 0,0:03:53.12,0:03:56.65,Default,,0000,0000,0000,,including the cortical regions \Nfor all the senses.
Dialogue: 0,0:03:56.65,0:04:00.68,Default,,0000,0000,0000,,LSD and psilocybin both function \Nlike serotonin in the brain,
Dialogue: 0,0:04:00.68,0:04:05.06,Default,,0000,0000,0000,,binding directly to one type of\Nserotonin receptor in particular.
Dialogue: 0,0:04:05.06,0:04:08.99,Default,,0000,0000,0000,,While serotonin’s role in the brain \Nis complex and poorly understood,
Dialogue: 0,0:04:08.99,0:04:12.60,Default,,0000,0000,0000,,it likely plays an important part \Nin integrating information
Dialogue: 0,0:04:12.60,0:04:13.38,Default,,0000,0000,0000,,from the eyes,
Dialogue: 0,0:04:13.38,0:04:14.11,Default,,0000,0000,0000,,nose,
Dialogue: 0,0:04:14.11,0:04:14.88,Default,,0000,0000,0000,,ears,
Dialogue: 0,0:04:14.88,0:04:16.74,Default,,0000,0000,0000,,and other sensory organs.
Dialogue: 0,0:04:16.74,0:04:21.02,Default,,0000,0000,0000,,So one theory is that LSD and psilocybin\Ncause hallucinations
Dialogue: 0,0:04:21.02,0:04:25.24,Default,,0000,0000,0000,,by disrupting the signaling \Ninvolved in sensory integration.
Dialogue: 0,0:04:25.24,0:04:27.94,Default,,0000,0000,0000,,Hallucinations associated \Nwith schizophrenia
Dialogue: 0,0:04:27.94,0:04:33.37,Default,,0000,0000,0000,,may share a similar mechanism with those\Ncaused by LSD and psilocybin.
Dialogue: 0,0:04:33.37,0:04:35.03,Default,,0000,0000,0000,,Patients with schizophrenia
Dialogue: 0,0:04:35.03,0:04:38.01,Default,,0000,0000,0000,,often have elevated levels \Nof serotonin in the brain.
Dialogue: 0,0:04:38.01,0:04:42.21,Default,,0000,0000,0000,,And antipsychotic drugs relieve \Nsymptoms of schizophrenia
Dialogue: 0,0:04:42.21,0:04:47.61,Default,,0000,0000,0000,,by blocking the same serotonin \Nreceptors LSD and psilocybin bind to.
Dialogue: 0,0:04:47.61,0:04:49.12,Default,,0000,0000,0000,,And, in some cases,
Dialogue: 0,0:04:49.12,0:04:51.68,Default,,0000,0000,0000,,these drugs can even relieve \Nthe hallucinations
Dialogue: 0,0:04:51.68,0:04:54.28,Default,,0000,0000,0000,,of patients with Charles Bonnet Syndrome.
Dialogue: 0,0:04:54.28,0:04:57.85,Default,,0000,0000,0000,,We’re still a long way from understanding \Nall the different causes
Dialogue: 0,0:04:57.85,0:05:01.23,Default,,0000,0000,0000,,and interconnected mechanisms \Nof hallucinations.
Dialogue: 0,0:05:01.23,0:05:03.70,Default,,0000,0000,0000,,But it’s clear that \Nhallucinatory experiences
Dialogue: 0,0:05:03.70,0:05:08.36,Default,,0000,0000,0000,,are much more closely tied to ordinary\Nperception than we once thought.
Dialogue: 0,0:05:08.36,0:05:09.87,Default,,0000,0000,0000,,And by studying hallucinations,
Dialogue: 0,0:05:09.87,0:05:11.45,Default,,0000,0000,0000,,we stand to learn a great deal
Dialogue: 0,0:05:11.45,0:05:14.38,Default,,0000,0000,0000,,about how our brains construct \Nthe world we see,
Dialogue: 0,0:05:14.38,0:05:15.09,Default,,0000,0000,0000,,hear,
Dialogue: 0,0:05:15.09,0:05:15.92,Default,,0000,0000,0000,,smell,
Dialogue: 0,0:05:15.92,0:05:17.22,Default,,0000,0000,0000,,and touch.
Dialogue: 0,0:05:17.22,0:05:18.15,Default,,0000,0000,0000,,As we learn more,
Dialogue: 0,0:05:18.15,0:05:22.25,Default,,0000,0000,0000,,we’ll likely come to appreciate\Njust how subjective and individual
Dialogue: 0,0:05:22.25,0:05:26.44,Default,,0000,0000,0000,,each person’s island universe \Nof perception really is.