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October 20, 2003
We know what you're thinking
Scientists can see your thoughts. You won't believe
what's on your mind.
by Scott C. Anderson
You no longer have to go to Madame LeFoni's to
have a mind-reading session. Scientists can read your mind too,
at least a little. And what they see when they look into your mind
is, well, thought-provoking.
How do those tricky scientists pull off this
legerdemain? They use a special type of MRI (magnetic resonance
imaging) that can measure minute flows of blood in your brain. Most
scientists have believed that blood flow correlates to neural activity,
but the proof has been hard to obtain. Is your brain really working
out – pumping irony, so to speak – or is the blood flow totally
unrelated to mental processes?
An experiment by Nikos Logothetis in 2001 put
this to the test. In a very delicate study, he showed a tight correlation
between the blood flow as measured by the MRI and electronic pulses
as measured by an electrode implanted in a monkey brain. This finally
put the science on a firm footing.
How does this spooky mind-reading trick work?
It uses an intriguing aspect of MRI, namely that it can precisely
locate specific types of molecules in a 3D space like your head
(unless your head is only 2D -- in which case we can read what's
on your mind by looking at your thought balloons). Using a variation
of normal MRI called BOLD (blood oxygenation level-dependent) contrast
they can actually distinguish the fresh blood that's carrying oxygen
from the spent blood that is oxygen poor. This sensitive MRI then
creates a 3D image on a computer showing what part of your brain
is getting oxygen when you are thinking certain thoughts.
So if you're thinking about a rib-eye steak smothered
in mushrooms (never write articles when you're hungry), can these
scientists see a picture of it in your brain?
Well, almost. There are layers of nerve cells
at the back of your head that act a lot like a movie screen, showing
a processed image of what your eyeballs are looking at. And there
are areas at the top of your brain that seem to map to a little
person laid across your cortex. When you stick a bite of steak in
your mouth and start to chew, a spot in your brain lights up, and
it's reliable – a good scientist can tell when you're chewing by
looking for that spot. Well, even a lousy scientist can tell you're
chewing by looking at your jaw going up and down, but the point
is that there's a definite correlation between the things that you
do and certain parts of your brain that light up.
At least that's the theory.
But lately, things are being stood on their head.
Turns out, if you just think about eating that steak, the
same chewing area lights up. Okay, that makes sense. You have to
think about it before you can make it happen, so maybe the scientists
are seeing the thought that leads to the action. But it turns out
to be stranger than that.
In one experiment, Giacomo Rizzolatti mapped
out all the brain spots that were involved with actually tossing
a ball. He then decided to see what would happen when the subject
merely watched someone else tossing a ball. Interestingly
enough, the same areas of the brain lit up. The part of the brain
that was involved in tossing is also involved with watching tossing.
Which means, among other things, that watching
Monday Night Football is good mental exercise. It also means that
people learn in a very direct way when they watch someone. They
don't just passively watch someone, they seem to model the motion
in their brains. And, having modeled it, they apparently find it
easier to emulate.
This leads to much interesting speculation. For
instance, if people can effortlessly mimic another person's brain
patterns, does that explain how people are able to relate to each
other? Is this the underlying circuitry responsible for empathy?
This synchronization extends to facial expressions
as well. When we watch another person talk, we often find ourselves
emulating their expressions, which in turn seems to lead to similar
blood flows and thus common brain patterns. Another person's smile
can actually make you happier, whether you want it to or not.
What happens if there is a break in this pathway?
What happens when you can't walk in someone's shoes because of some
lousy brain chemistry? Could that explain pathological behavior?
The natural, built-in ability to model another
human like this is an extraordinary discovery. Far from being the
lone wolf, man has -- built into some primal circuitry -- an ability
to resonate with his fellow man. For all our theories about selfishness,
blind greed and Darwinian struggles, on some deeply biological level
at least, we feel the pain of our fellow man.
Some people, like Saddam Hussein, have managed
to rise above their compassion. They demonstrate that biology is
not necessarily destiny. But for the rest of us, helping our fellow
man may directly contribute to our own happiness. You needn't believe
in fairy godmothers for it to work, either. This is a measurable
biological phenomena. It's hard to refute mother nature.
Those party-poopers who believe that violence
is a cornerstone of humanity have received a setback. Indeed, the
research implies that when violence flares up, it is most likely
because there is a madman for people to emulate, not because of
a lack of sympathy on anyone's part.
Our brains actually seem wired to produce understanding,
not anger. And that may be some of the most hopeful news about humans
in a long time.
For more information about the brain, click on
these links:
The
Scientist
Nature
Copyright © 2000-2004 by Scott Anderson
For reprint rights, email the author:
Scott_Anderson@ScienceForPeople.com
Here are some other suggested readings
about the brain:
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