Ever tried showing a porn film
to someone who is lying in a brain scanner? It’s not easy. First, the scanner
contains a powerful magnet that will drag anything that’s metallic and not
properly bolted down – including bits of TVs – into it at high speed. Even if
that doesn’t happen, the magnetic force might play havoc with the electronics.
Then there’s the noise. MRI scanners aren’t exactly quiet. The intrusive
humming and banging noises would undoubtedly be a distraction to anyone trying
to get in the mood. To make matters worse, the volunteer has to lie perfectly
motionless for you to be able to get a clear image of their brain. All in all,
it’s not conducive to a happy viewing experience.
But at Northwestern University
in Illinois, they have managed to overcome these practical difficulties. The
erotic movies, downloaded from the internet or on DVD, are played onto a screen
behind the scanner from a projector that’s outside the room. The volunteer can
watch the X-rated action using a mirror just above their eyes. To block out the
din of the scanner, the volunteers wear headphones and the sounds they need to
hear are relayed through those.
But the problems don’t end
there. “In general we know that men are more interested in visual erotica,”
says Adam Safron, a research consultant at the university. “It’s a more
difficult task finding stimuli that women like to the same degree.”
Lust
These are the challenges faced
by neurologists at Northwestern who are trying to understand what goes on in
the brains of men and women when we have feelings of Lust. Their research is
certainly unusual and reveals that we’re hard-wired to sin. The scans show that
in both sexes, the evolutionarily ancient limbic system, buried deep inside our
brains, fires up when we are watching something we take a fancy to. Structures
like the nucleus accumbens, involved in pleasure and craving, are at the heart
of that system. It’s the enjoyable face of sin. And there’s an obvious reason
why we’d be hard-wired for lust – to pass on our genes. It’s in Mother Nature’s
interest to encourage us to take an active interest in procreation.
Gluttony
The reward circuitry in our
brains also lights up when we eat. “We find these things rewarding because of
the evolutionary logic – you want organisms to reproduce, you want them to
eat.” But eating itself isn’t a bad thing. It’s only a problem when sustenance
turns to gluttony. And even here it seems that we have nature to blame. “In the
environment that we evolved in, food was scarcer – there were no cheesecakes
and no hamburgers,” says Safron. “Throughout most of our history, life was very
difficult and these were the conditions that shaped our brains – set the dials
for how much we want these things or how rewarding we find them.”
So what was once a dial setting
for self-preservation is now a dial setting for sin – and it’s more of a
problem for some than others?
“Some people have their dials
set to overdrive,” Safron continues. “They are too motivated to achieve certain
things and it ends up being unhealthy in a modern lifestyle. That same
biological predisposition would have made them well adapted organisms in the
past.” Many of us, it seems, have been born a few centuries too late – that
irresistible cheesecake-devouring impulse would have stood us in good stead in
4000BC.
Sloth
Safron also believes sloth – or
the tendency to do absolutely nothing – has its roots in our evolutionary past.
“You never knew when your next big meal would be coming, so if you could, you’d
rest. The calories you don’t burn in activity, you could use for growth
processes or to repair your body.” So that’s it. Mother Nature has wired our
brains for certain things to be pleasurable to maximize the chances we’ll pass
on our genes.
But not all sins are
pleasurable. Take envy for instance. Whether it’s a work colleague who has just
won a promotion or a team-mate who has made it into the first team ahead of us,
no-one actually enjoys that feeling.
Envy
But at the National Institute
of Radiological Sciences in Japan, they’ve been deliberately provoking the
green-eyed monster. A group of male volunteers were presented with descriptions
of three people. One of them was a success: highly intelligent, they were
flying through university and had the same goals in life as the volunteers. To
really rub salt into the wounds, they were a real hit with the ladies and had a
very attractive girlfriend. The second person was female – also intelligent and
popular with the boys, but not really having the same goals in life as the
volunteer. The third person, again a girl, was something of a loser – a
mediocre, unpopular student. The same descriptions were handed to the female
volunteers, although the sexes of the students described were reversed.
As they read these
descriptions, the volunteers were hooked up to a brain scanner to show where
most blood was flowing in their grey matter and thus which region was the most
active. In all the volunteers, without exception, reading about the high-flier
with the attractive partner provoked a reaction in the brain region known as
the anterior cingulate cortex (ACC).
“This area of the brain is also
involved in the processing of physical pain, so envy is a painful emotion,”
says Hidehiko Takahashi, one of the researchers involved in last year’s study.
So if envy hurts, why would Mother Nature be so cruel as to wire it into all
our brains? The important message from the study, says Takahashi, is that there
was the biggest response in the ACC when the volunteers and the students they
were reading about had the same aims. “There’s a positive or constructive
element to envy: it motivates us to improve our own performance. Or, if it’s
difficult to beat your rival, another strategy is to change your goal or
interests.” But envy does have a dark side. “It could also make us want
something bad to happen to the other person. So it can induce immoral behavior
or even a criminal act.”
Pride
Pride too, it seems, has its
positive side. At Montclair State University just outside New York City, they
have been temporarily knocking out certain parts of the brain using trans
cranial magnetic stimulation (TMS). The idea is simple. 3 3 If you can stop a
certain portion of the brain from working, you can find out what it does. So a
magnetic coil is placed near the volunteer’s head, disrupting the firing of the
brain cells, or neurons. Volunteers wear something that resembles a swimming
cap with markings on it so a specific spot in their grey matter can be
targeted.
Aim the coil around the
forehead, so that the magnetic field hits the medial prefrontal cortex (MPC) at
the front of the brain, and something interesting happens. “What we normally
see, at least in your everyday American subjects, is a small sense of
enhancement,” says Professor Julian Paul Keenan, director of Montclair’s neuroimaging
lab. They think they are a little bit better than they are.” But TMS can switch
that self-enhancement off. The words the participants use to describe
themselves and their friends suddenly change. “Without brain stimulation, they
are more likely to say, ‘I’m intelligent and my best friend is not.’” But with
the coil switched on, pride is switched off – the vocabulary people use to
describe themselves is much less flattering.
“We’ve just finished studying a
phenomenon known as ‘over-claiming’, where people pretend to know things they
don’t. I’ll give them a made-up word like ‘trianic’. They really think they
know this term, even though it’s not a real one. They say ‘Oh yeah, I’ve seen
that word before, it’s something to do with biology.”
Again, a little zap with the
coil stops this in its tracks. Interestingly, Keenan’s work shows that
self-deprecation originates in the same area, so it looks like its just
arrogance – or pride – in disguise. “They’re just different sides of the same
coin,” he says.
The research has moved on at
Montclair. They are currently testing whether removing that pride by knocking
out the MPC makes the volunteers a little more depressed – they simply fill out
a depression score before and after the test. So far, it’s too early for
results. “Others have found that people who don’t have this self-enhancement
tend to be clinically depressed. So if you realize how fat you really are, it’s
going to drag you down. If you see yourself as others see you, it tends not to
be a good thing, so a little bit of ego is pretty good.”
Again we’re back to that same
idea – moderation. “It’s a common theme in biology – not too much, not too
little,” says Safron. But some people’s dial settings are set too high – at
least for the modern world.
It would make sense then for
us, the ‘civilized’ species on this planet, to have developed some kind of
self-control to keep our most basic of instincts in check. In one experiment at
the University of Montreal in Canada, male volunteers watched clips of erotic
films as their brains were scanned. And the clips produced responses in the
deep, primitive parts of the brain such as the amygdala – no surprises there,
then. But when they were asked to mentally suppress their sexual arousal, two
different parts of the brain sprang into life – their right superior frontal
gyrus and the right anterior cingulate gyrus. These are both found in the
frontal lobes, the part of the brain that makes humans human, leading to, among
other things, self-awareness.
Wrath
Studies of wrath paint a
similar picture. Some rather brave scientists at the University of New South
Wales in Australia hurled abuse at volunteers in a brain scanner to see what
would happen when they got angry. In those who were brooding types, rather than
those with a short fuse, the medial prefrontal cortex (again part of the
frontal lobes) quickly fired into action. It’s a region involved in moderating behavior.
“Some people are better at
inhibiting their impulses than others,” says Safron. “Some people may have the
same drive towards a particular kind of behavior, but less frontal inhibition.”
So in some of us, it seems, the primitive beast within is more likely to win
out.
The choices we make in life are
often the result of this conversation between the advanced and primitive
regions of the brain. “These evolutionarily ancient parts of the brain are
constantly interacting with the cortex – which has expanded more recently – to
produce behavior.” But, says Safron, the emotional part of the brain – the limbic
system – and the advanced cortex need each other to work. “If you sever the
connections, it becomes difficult for someone to regulate their behavior.”
Nowhere has this been spelled
out more clearly than in a study of psychopaths carried out at King’s College
London. Last year, researchers used a powerful new scanning technique,
diffusion tensor magnetic resonance imaging, to study the brain structure of
nine criminals with convictions that included attempted murder, manslaughter
and multiple rape with strangulation. It was found that the psychopaths had
poorer connections between their amygdala (in the emotional, limbic part of the
brain) and their prefrontal cortex than others of a similar age and IQ.
Greed
But haven’t we forgotten
something here? Isn’t the way we behave supposed to be the result of nature and
nurture – the influences that shape us as we grow up? Unfortunately, when it
comes to greed, there are no brain studies to provide us with the answers. “The
mechanics of greed may be more complicated,” says Safron. “Gluttony and lust –
if anything could be influenced by biological predispositions, they are. We
know for instance, there are neurochemicals that increase or decrease your
libido. But there are some things that are universal, which aren’t necessarily
innate, and greed may be one of those things. There could be an innate basis
for greed, but because it seems to be more complex, it is probably more likely
to be shaped by learning.”
So the degree to which its
nature – the shaping hand of evolution – or nurture that encourages us to be
bad depends on the sin. But when it comes to the simplest of desires – to eat
and have sex – there’s no doubting what’s at the heart of them. “I heard it
said that emotions are evolution’s executioners – they are what natural
selection uses to make organisms successful at propagating their genes,” says
Safron. We’re nature’s puppets – dancing to a pre-ordained tune that’s been
reinforced through the generations. Now that’s a great excuse to demolish a
cream cake if ever there was one.
(Source: sciencefocus.com)
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