Kind: captions
Language: en
for some people an entire half of their
brain can't really communicate with the
rest these are people who have undergone
split brain surgery and it's as
if they have two minds in a single brain
the human brain contains two sides the
left hemisphere and the right hemisphere
right and they are connected by a big
bundle of fibers it's called the Corpus
colossum all the communication from one
side of the brain to the other has to
pass through this fiber bundle for some
people with epilepsy a seizure in one
hemisphere can quickly spread to the
other by way of the Corpus
colossum but if that bridge is
surgically severed a seizure can no
longer cross to the other side of the
brain in addition to treating epilepsy
these surgeries have also led to some
astounding Research into how the two
hemispheres function with your left hand
make me the AOK sign
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to learn more about these fascinating
studies I met two Pioneers in the field
Michael Miller and Michael
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gazan Michael Miller asked me to step
into his lab to do a few simple tests
just like the ones he's conducted with
patients after a split brain surgery so
Heather what you going to see our two
shapes they going to come up on the
screen you'll draw the shape on the left
side of the screen with your left hand
and the shape on the right side of the
screen with your right hand and I want
you to draw them as quickly as you can
at the same time okay piece of cake
right
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beautiful okay I'm not sure what you're
drawing over here
but oh that's did I mention I didn't get
that much sleep last night
the left side of the brain controls most
of the right side of the body and the
right side of the brain controls most of
the left side of the
body Happ is I start out trying to do
different things and then they just sort
of like syn up together
yeah come on man it's perfectly normal
so I mean what's happening is that the
motor commands in the in one hemisphere
you're interfering with the motor
commands in the other
hemisphere it was basically impossible
for me to force my hands to draw two
different things at the same
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time but for someone whose two
hemispheres are disconnected there's no
interference it's almost as if there's
one mind controlling the left hand and a
completely different mind controlling
the right hand and it isn't just
movement that's split across the
hemispheres only half of your visual
field goes to each side of the brain
when you're looking Straight Ahead
everything to the left side of that
space goes only to the right Hemisphere
and the opposite is true for the right
side in the
space the left part of the brain is
where your language and speech centers
are that enables you to talk labeles you
to understand language and all the rest
and the right side of your brain is very
important in the evaluation of emotions
evaluation of visual
space the researchers conducted tests to
explore how a split brain patient's two
hemispheres work independently from one
another including a now famous
experiment of a patient named
Joe by quickly flashing a word to just
the left side of his visual
field that word would go exclusively to
the right half of his brain the half
that can't
talk so the only way we're going to know
that it registered is if he can write
something out
okay with his hand that is controlled by
his right hemisphere exactly his left
hand we Flash the word
Texas right
that see it and Flash see the
word his right hemisphere is seeing it
we're seeing it but but the right
hemisphere uh at this point in his
surgery cannot talk right all right I
want you to draw for me uh that thing
upside down so he claims to not have
seen anything yeah oh my
god wow he was able to do Texas upside
down but what's interesting is he had no
idea what he's drawing and we know
because we saw the word I can't tell
what it is the split brain phenomenon
suggests that there can be two separated
Minds if you will inside of a skull the
cooperation is on the paper not inside
the head it's a astounding example of
cross queing and management of two
mental systems into one unified Act and
the idea is maybe that's going on in us
all the time too