When I say hallucination you probably think of one or two things,
psychotropic experimentation like a
dude in a hemp shirt tripping at a fish show
watching rainbows melt into puddles,
or mental illness, like someone doing things because the voices in their head told
them to and ending up in the hospital
...or in jail. A few centuries ago most people would have described hallucinations through
the influences of ghosts, gods or witches.
Today we understand them as the result of neurological disturbances and the truth is
hallucinations aren't necessarily a sign of mental illness, drug use
or spirit vengeance, rather they can be caused by lots of different things.
So while not everyone has experienced hallucinations, it's important to
understand that everyone is capable of hallucinating under the right circumstances.
In fact, a good number of us will experience some type of hallucination in our lifetime.
I know I have. Like if you've lost the use of one of your senses like your
sight or smell, but still smell things from time to time,
then you've hallucinated. If you've been under a ton of stress and heard someone tell you
what to do only to find that there's no one there...
Then you've hallucinated. If you've driven by a bus stop and for a split second saw
your deceased father sitting on the bench reading a newspaper,
then you've hallucinated. It's weird, I know. But the one thing I can assure you
is that the science behind these phenomena, is very real.
[Intro music]
Whether they're fun, enlightening, confusing, or terrifying,
all hallucinations involve sensing things that appear to be real,
but actually are a product of the mind. They're not dreams,
you have to be awake to truly hallucinate - instead they're sensory disturbances,
coming in a variety of flavors. You can see light patterns and objects that aren't there,
smell imaginary odours, hear voices and other sounds, or feel physical
sensations like crawling skin or your own organs moving. Even out-of-body,
near-death,
and sleep paralysis experiences are types of hallucinations.
But to understand what's not real, you first have to understand how your brain judges
something to be real in the first place.
This involves the sister processes of sensation and perception -
two different things. Your sensory organs receive visual, auditory, olfactory, and
tactile clues pulled from the outside world in a process called sensation.
That raw data is then sent to the brain where it's processed,
giving it meaning, putting it into context in the process of perception.
So, basically the brain turns sensory input
into meaningful information to create your own model understanding of the world.
The more sensory data you collect,
the more they inform that model of how you perceive the world to work, and most
people's models more or less agree on the big stuff -
the sky is blue, the dogs bark, kittens cannot fly, and snow is cold.
But if that normal copacetic brain activity gets disturbed by say
a dose of LSD, a seizure, a disease or a mega blow to the head,
this model can get shaky, eventually diverging from its normal representation
of the world
then suddenly a flock of kittens fly by in a fiery rose scented rain while calling your name.
Depending on the type of brain tweak these hallucinations may take different forms
interesting, random, or scary - the good news is they all give us potential to learn about
what the heck is going on up here. Obviously outside substances can spur
some wacky activity in your mind,
and most ancient cultures have some tradition of vision questing aided by
some psychotropic substance.
I'm not gonna get too into drugs today but you should understand the different
compounds whether found in plants, animals, fungus, or synthetically made concoctions
affect the brain very differently, meaning that even if they all cause
hallucinations, they may be using very different pathways - for example, most
researchers agree that LSD garbles the senses in a psycho-biochemical way, by
affecting specific feel-good serotonin receptors found in the brain's cerebral cortex
and thalamus regions responsible for sensory perception. Caffeine
on the other hand works in an entirely different way. Australian researchers
have linked consuming excessive amounts of coffee with increased risk
of auditory hallucinations. Caffeine sorta gooses the physiological effects of stress
including the increased production of the bodies naturally occurring stress hormone cortisol,
which can lead you to hear things that are not actually there.
But there are many reports of healthy, non-caffeinated people experiencing vivid
auditory hallucinations,
often when under extreme stress. There have been recorded cases of, for example,
someone breaking their leg while alone in the woods and just wanting and curl up and die,
but a strong voice, not just a thought, but something that seemed
actually audible, telling them they need to get up
and move to survive. Grief is its own kind of stress of course, and hallucinations
have been known to occur in otherwise healthy people during periods of extreme grief -
in fact, people seeing a departed loved one or hearing their voice
can be a common part of the grieving process. But hearing voices is the symptom
we typically associate with mental illness,
and while it's true that seventy percent of schizophrenics report hearing voices regularly,
it's not necessarily a scary thing. In fact, one Dutch study found that a good number
of mentally stable people enjoyed hearing pleasant, supportive voices in
their heads. Exactly how a person experiences auditory hallucinations is still fuzzy,
but some neuroimaging studies suggest that it may have to do with the failure
of the brain's frontal speech area.
This is the part that usually lets your sensory areas know that the sound they're hearing
is self-generated, like something you're just thinking to yourself, but if that signal
doesn't get sent,
then the brain gets confused as to where that voice it's hearing is coming from.
Brain scans have also shown that people with schizophrenia have abnormalities in
the areas associated with memory.
That might exacerbate this failure to identify the words that show up in their
mind is being part of their own inner monologue. Here's something interesting though -
in the total absence of sensation
the brain still leaps to perception, wanting to maintain that connection.
For example, some people who suddenly lose their ability to smell
often experienced phantosmia a a type of olfactory hallucination. And yeah,
if you smelled wildflowers and baking cookies it might not be so bad, but
unfortunately the most common odours
are the bad ones like puke, poop, and rotting stuff.
In these cases your brain is overcompensating for its lack of
olfactory input by pulling from the memories of old scents
and making it seem like you're smelling them for real. It's possible that the brain's
offering up these disagreeable odors because those very smells
had just been suppressed by certain neurons that had since
turned off. And it doesn't stop with smells, in fact one of the most fascinating
ways to see visual hallucinations
is to go blind. Charles Bonnet Syndrome, or CBS
is a condition that can cause otherwise healthy people with macular degeneration
or loss of vision
to experience complex visual hallucinations. The condition was first
described by Swiss naturalist Charles Bonnet
in 1760 after watching his nearly blind grandfather describe seeing visions of birds,
buildings, and ladies, among other things. Patients with CBS report seeing images
ranging from simple geometric shapes and colors
to vivid detailed scenes, often involving faces and for some reason
lots of little people. But these images are not interactive, the experience is more like
watching a movie with the sound off,
and what patients see is unrelated to anything they're thinking, feeling, or
doing at the time,
and none of the faces are familiar. Some are pleasing but others are deformed,
and they often have big misshapen teeth. These types of hallucinations are very
different from psychotic hallucinations,
which tend to be interactive and actively address the patient, whether to support,
berate, threaten, or jeer at them. Instead
CBS hallucinations are more like those people with olfactory damage who start
to hallucinate smells.
When a person's vision no longer functions, the visual part of their brain
can become hyperactive
in the absence of stimuli that it was used to. So, it starts firing off
images trying to sort of keep the story going,
guessing what it might be seeing if it could still see. Interestingly the same
phenomenon can be achieved under visual sensory deprivation. One study
blindfolded volunteers for four days and in the end ten of
the thirteen subjects reported seeing various levels of hallucinations. Different
localized parts of the brain are often involved in specific hallucinations
too, like there's an area for seeing buildings and landscapes,
and one just for cartoons. There's also a region in the temporal lobe called the fusiform gyrus,
which is where we process the images of people's faces, so damage to this
area can cause prosopagnosia,
or face blindness - the inability to recognize faces, sometimes even your own.
But over activity in this sliver of the brain can cause a person to hallucinate
and start seeing, you guessed it, faces. Not only that but the front part of
this region specializes in registering
teeth and eyes specifically, so it may be involved in the phenomenon of hallucinators
seeing faces with crazy big teeth. So even though you and your brain may sometimes
see things a little differently -
sometimes a lot differently - you can think of hallucinations as particularly
vivid reminders of just how delicate, complicated, and freaking amazing your brain is.
Take care of it, and it will likely do its best to take care of you.
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