The reason why evolutionary economics (and the
neurosciences) can give more convincing explanations than conventional
economics about why man ever started trading and economic systems in the
first place -- when, at the survival level he had no need to -- is due to
the vast extension of the frontal lobes of our brain, well beyond those
of the other primates.
Whereas other animals have urges that well up from the evolutionarily
older parts of the brain, primate species (to a little extent) and our
species (to a much greater extent)accompany the satisfaction of basic
urges with a great deal of additional pleasure. Whereas, for example,
both the male chimpanzee and the human male have urges to attain the
highest possible rank in his group, it is only the human male that
obtains the additional exquisite satisfaction from its attainment by
virtue of his extensive frontal lobes. It is a matter of the satisfaction
of our urges -- but with a big plus. Not only this, but the highly
sophisticated frontal lobes that we possess also enable man to embellish
quite ordinary objects with extra significance so that basic urges are
imbued with a great deal more pleasure than mere satisfaction.
Thus, a male chimpanzee will strive to attain a top ranking in his group
more or less unconsciously -- rather like Hillary's motivation to climb
Everest: "just because it's there". On the other hand, when a
male human reaches the top rank he makes the occasion far more
pleasurable by dressing in a fancy uniform, or presiding over grand
ceremonies or, as happened in the earliest days of man 75,000 years ago,
by decorating his body and face with pigments (something that all
'primitive' societies still do to this day). And, in order to gain the
pigments he needed, he would obtain them by trading with any adjacent
tribe that had access to them. And, as archeological researches are now
showing us, some of these pigments could only be obtained by consecutivfe
trading between tribes over long distances between source and
destination.
And that is the general origin of our economic systems. The trading of
goods and services is for reasons far beyond mere survival and if we are
to understand economics beyond the simple mechanisms of supply and
demand, the hidden hand, laws of diminishing returns and so forth, we
have to understand that economics is deeply intertwined, via our frontal
lobes, with far more powerful emotions than physical survival and mere
gratification -- the level at which most economic text books
remain.
It has taken neuroscientists several decades and a great deal of careful
experimentation to understand the difference between the satisfaction of
our basic urges and the additional pleasure that we gain by embellishing
them in imaginative ways via our frontal lobes. The following article
describes this research for the general reader extremely well and will
repay careful reading by anybody who is interested in what drives our
economic systems.
Keioth Hudson
<<<<
THE PLEASURE SEEKERS
Hedonism makes our world go round, but it goes a lot deeper than our
obsession with sex, drugs, rock'n' roll and chocolate. Neuroscientists
are completely rethinking how our brains give us pleasure, and as a
result are starting to believe that the quest for pleasure may underpin
every decision we make. It may even have laid the foundations of
consciousness
Helen Phillips
It was an outlandish, ethically questionable experiment, but this was the
1960s after all. Psychiatrist Robert Heath of Tulane University in New
Orleans hoped to cure his patients' depression, intractable pain,
schizophrenia, suicidal feelings, addiction, and even homosexuality --
which in those days was considered a psychiatric disorder -- by drowning
them out with pleasure, induced by an electrode implanted deep in their
brains.
Heath's experiments were based on findings from a decade earlier that
administering a mild electric shock to the equivalent brain area in rats
-- the "reward centre" -- would send the animals into a state
that looked like ecstasy. The rats would work at complex tasks over and
over for the promise of another shock. Heath wondered whether his human
subjects would react in the same way -- and they did. When they were
given a shock they said they felt good. And when handed the electrode's
controls, they just kept on pressing, again and again, sometimes a
thousand times in succession.
Unfortunately for Heath, the good feelings waned almost as soon as the
current was cut and the method did not provide any long-term benefit.
Heath himself eventually moved into other lines of psychiatric research.
But his experiment remained one of several that cemented the orthodoxy
that creating pleasure in the brain was a simple matter of pressing the
right neurochemical lever. For poets, writers and metaphysicians down the
ages, pleasure had been a subtle, many-sided enigma to do with
contemplating the likes of God, love or a beautiful garden. But now it
seemed Nirvana could be equated with squirting a few microamps of
electricity into a tiny part of the midbrain.
By the 1980s, the circuit diagram of this reward centre had been worked
out. A whole series of brain areas had been charted and the chemical
transmitter that passed messages around was known to be dopamine -- hence
the reward centre's alternative name, the "dopamine system".
Everyone agreed on the centre's function, too. It rewarded animals for
doing things with survival value -- eating or having sex, for example. In
the years that followed, the reward centre and dopamine release were
linked to every natural and unnatural pleasure imaginable -- everything
from the cotton-wool whoosh of heroin and the wham-bam of orgasm to the
gentler satisfaction of a rich meal or the thrill of winning money. And
until recently that's pretty much how things still stood. The role of
this brain area in addiction has also been explored in thousands of
papers and studies. Millions of dollars in research grants have been
spent dissecting its every neurochemical quirk. Its role is to make us
feel good. It's the brain's G spot.
Except that some scientists think the issue of pleasure in the brain is
far from settled. At the University of Michigan in Ann Arbor,
neuroscientist Kent Berridge is carrying out experiments that just don't
fit the picture. He thinks the electrodes were filling those patients and
rats not with pleasure, but with a subtly different feeling -- desire.
Heath and other researchers, he thinks, mistook wanting for liking.
Meanwhile, Edmund Rolls at the University of Oxford has been
finding pleasure in a completely different brain area, the orbitofrontal
cortex just behind the eyes. And Jaak Panksepp of Bowling Green State
University in Ohio, Ann Kelley from the University of Wisconsin, Madison,
and others are discovering that opioids, not dopamine, may be the real
key to transmitting feelings of pleasure.
No one can quite agree how all the findings fit together, but they are
gradually evolving into a new model of how and where pleasure is
registered in the brain. The basic idea that pleasure is a reward for
doing something that promotes survival remains important, but pleasure is
turning out to play a much wider role. It seems to be involved in all
types of decision making, from choosing food to solving mathematical
problems. Pleasure helps us plan our movements and allows our brains to
filter and sort the mass of smells, sights, sounds and other information
that bombard our senses. It may have been the origin of all our emotions.
Perhaps even consciousness itself evolved from the simple sensing of
pleasure and displeasure.
At first glance, the "reward centre" idea seems hard to fault.
The self-stimulation experiments, beginning with rats in the 1950s and
followed by the human experiments in the 1960s, seemed perfectly clear.
Modern brain-imaging studies have confirmed that the centre works
overtime whenever you're enjoying something, whether it's sex or
chocolate, drugs or music. And chemical analysis shows that, whatever
your pleasure, dopamine fuels the circuit. "Dopamine was the
pleasure transmitter," says Berridge. "The evidence seemed so
strong. If you shut down dopamine signalling by giving a drug that blocks
dopamine receptors, you dilute the reward value of everything." So
why did he and others begin to question the status quo?
Berridge reckons that his doubts began to creep in around the late 1980s,
with a few surprise results. He'd found that he could watch rats' facial
expressions to judge their reactions to certain tastes. Believe it or
not, rats actually look pleased when given sweet things to taste, and
produce the rat equivalent of a disgusted look in response to bitterness.
The assumption was that these expressions were of pleasure or
displeasure, mediated by the reward centre. The surprise came when
Berridge blocked the dopamine signal with drugs. In theory, with dopamine
knocked out there was now no way for the rats to sense the reward value
of the sweetness, so he was expecting not to see any "pleased"
expressions. But the rats seemed just as expressive as ever.
Putting it down to experimental error, Berridge tried a more foolproof
test. He used rats in which dopamine-producing cells had been wiped out
with a neurotoxin. It was already known that these animals simply stopped
eating. "They would voluntarily starve to death if the experimenter
didn't intervene and feed them," says Berridge. Researchers had
always thought that the rats' lack of dopamine meant they didn't like
food. But when Berridge force-fed them with sweet and bitter liquids,
their facial reactions were normal. "They still showed the proper
positive face to sugar and the proper negative face to quinine," he
says. "It looked like their reaction to pleasure was normal even
though their dopamine was gone."
What was going on? The experiments prompted Berridge to look back at
Heath's brain electrode results. He was struck this time by what feelings
the subjects reported. They all said they felt good, and always pleaded
for more when the controls were taken away. But was it pleasure? The
reports mentioned feelings of alertness, warmth and goodwill, arousal, a
desire to masturbate, or to drink even though they weren't thirsty. It
sounded more like desire than pleasure. This fitted perfectly with
Berridge's rats. Even with no activity in the reward area, they seemed to
"like" the taste of sweet food. They just didn't
"want" it. Could the dopamine system be a desire circuit that
mediates our feelings of wanting something, rather than a pleasure centre
that supplies our feelings of liking?
Although it was Berridge who drew attention to the distinction between
wanting and liking, he is by no means the only researcher to realise that
"pleasure" is not quite the right term to attach to activity in
the dopamine system. If people are given drugs that block or stimulate
dopamine release, it doesn't alter how much they report liking certain
tastes. What that suggests is that the dopamine system itself doesn't
produce feelings of pleasure, says Panksepp. "The dopamine system is
about motivation and seeking. It gives a generalised desire or urge, an
eagerness to engage with the world."
Studies of drug addiction add weight to the idea that the dopamine system
is not about pleasure but desire. Addicts always end up needing more of
their drug to keep the pleasure level steady. But they never say they
develop a greater "liking" for any drug -- they just
"want" it more and more.
George Koob, a neuroscientist and addiction specialist at the Scripps
Research Institute in La lolla, California, agrees that dopamine is
primarily involved in activating both movement and thought. And while he
believes that its release can be directly pleasurable because it gives us
a sense of power and a sense of enjoyment in "getting going",
the dopamine system seems more important for helping us to make the
behavioural choices that will help us achieve the goals it has told us we
desire.
Pleasure chemicals
So where do we actually feel pleasure? It's not just a trivial
question. According to Kelley, only by understanding the brain's pleasure
and desire circuits fully are we likely to make progress in understanding
two of the biggest threats to public health in the developed world,
obesity and drug addiction.
One suggestion is that pleasure comes from a different group of brain
chemicals. Pleasurable drugs don't just activate the dopamine system,
they also trigger the release of endorphins and encephalins -- a family
of chemicals known as the opipids, which include drugs such as morphine
and heroin. These chemicals all seem to activate a circuit deep inside
the brain which overlaps with the dopamine system. Could this opioid
circuit be the source of pleasure, while dopamine produces the related
feeling of desire?
One clue that the opioids are involved in pleasure is their well-known
effect on appetite. Even before the brain's own opioids and their targets
were found, neurobiologists knew that heroin and morphine could bring on
the munchies and seemed to enhance the pleasure of eating. More recently,
naloxone, a chemical that blocks the action of opioids, has been found to
reduce people's enjoyment of food without reducing their feelings of
hunger, making things taste less pleasantly sweet, for example. What's
more, Panksepp has found that young rats that are distressed by being
separated from their mothers, for example, release opioids when they
return, and can be calmed without their mother by opioid drugs. He
concluded that social pleasures, particularly the feelings of comfort and
safety associated with social bonding, are produced by opioids too.
Opioids, then, seem to mediate "liking".
So where are the opioid receptors in the brain? Some are sprinkled at
either end of the old reward centre, which has led many researchers to
argue that opioids merely complement the action of dopamine.
More recently, however, Berridge and others, notably Kelley, have found
that the opioid receptors are not confined to the dopamine system but are
widespread in the brain. Berridge believes what they have found is a
distinct pleasure circuit, driven by opioids. It overlaps considerably
with the dopamine system, to the point where some cells take part in both
circuits. But its role and chemistry are quite different.
Early results seem to show that one of the most important sites for
"liking" is the ventral pallidum, a small region deep in the
brain, near the dopamine system. Opioid injections into this area seem to
boost enjoyment of sweet tastes, while damaging it makes all normal
liking disappear -- as seen by the lack of pleased facial expressions in
rats given sugar. "This is a prime candidate for coding
liking," says Berridge. The ventral pallidum takes in signals from
the nucleus accumbens -- a central component of the dopamine system --
and passes them on to the cortex. He believes it could well be at the
heart of our liking response.
And if this brain structure is the heart of pleasure, then a team in
Oxford may have located its head. According to their research, pleasure
is not created solely by deep brain structures and opioid cells. Cells
nearer the surface of the brain have a vital role as well. And
astonishingly, it seems that each form of pleasure is linked with a
unique subset of these neurons. Some of the cells react to sweet food,
others to eating fatty morsels, others to monetary reward, and so
on.
The cells are all in a region of the forebrain called the orbitofrontal
cortex (OFC), so-called because it lies behind the orbits of the eyes.
The region has long been known to have something to do with emotions. But
the Oxford team, led by neuroscientist Edmund Rolls, have now put it in
the hedonistic driving seat.
Rolls points out that pleasure, like other emotions, is a direct response
to a sensory stimulus. And one of the first brain regions to process
sensory information is the OFC. Signals such as taste, touch, smells and
sounds travel first to the sensory cortex, and from there go straight to
the OFC. Visual information enters by a slightly less direct route. From
here the signal passes into the opioid and dopamine circuits.
When he scanned the brains of human subjects using fMRI (functional
magnetic resonance imaging), Rolls found that a nice or nasty smell,
taste or touch is represented in the sensory cortex simply as a magnitude
-- strong brain activity for a strong smell and weak brain activity for a
faint one, for example. But by the time it has passed on to the OFC the
strength of the fMRI signal now correlates with how nice or nasty people
rate the stimulus. As each sensory signal passes through the OFC, it is
as if it becomes tinged with a level of liking or disliking.
Crucially, Rolls and his colleagues found that activity in the OFC
increased or decreased in line with the level of pleasure people reported
they felt after drinking, eating or sensing a touch. Even abstract
pleasures such as music, attractive faces and financial reward seem to
correlate with activity in this region. And each form of pleasure is
linked to a unique group of neurons. Some may react to sweetness, others
to fat, others to monetary reward. All told, about 10 per cent of the
neurons in the OFC may be pleasure sensors.
Most pleasure sensors are probably inbuilt, Rolls suggests, encoded in
our genes and honed by evolution. But the OFC can learn others. There's
no innate circuit for monetary reward, he points out, but one could
easily be built through learning. Money could come to be associated with
food rewards or comfort, and become rewarding in its own right.
The OFC, says Rolls, also calculates when you should stop partaking in
something pleasurable, through an effect he calls sensory-specific
satiety. After a while any reward loses its appeal. It's not clear what
causes the effect but it seems to be linked to a drop in activity in the
pleasure cells. He believes drugs wreak their havoc because they tap
directly into the opioid and dopamine circuits, bypassing the OFC, which
might otherwise put the brakes on by exerting some kind of
satiety.
The ventral pallidum and OFC are central to the new view of pleasure, but
other brain regions may be involved too. A team at the university of Iowa
in Iowa City has uncovered evidence that other parts of the brain's
cortex become especially active during pleasure, or at least when people
recall situations that gave them pleasure. Working with his colleagues
Hanna Damasio, Daniel Tranel and Antoine Bechara, neuroscientist Antonio
Damasio used PET scans to show that the cingulate cortex and
somatosensory cortex light up in this way. Damasio thinks the observation
points to a crucial distinction that must be made between pleasure as an
"emotion" and pleasure as a "feeling". He sees
emotions as physiological processes that guide behaviour, whereas
feelings only arise when the brain experiences those physiological
processes and reflects upon them.
According to Damasio's model, the emotion of pleasure may well involve
the dopamine and opiate circuits and OFC. But actually feeling pleasure
requires a level of reflection that can only be provided by these other
brain regions. These, argues Damasio, enable us to sense how the
physiological process changes the body's state. And as such they come
from the parts of our brain that carry sensory maps or representations of
our bodies -- the cingulate cortex, somatosensory cortex and certain
parts of the brainstem.
Having discovered pleasure centres all over the brain, researchers are
now asking, what are they for? And the answers they are finding suggest
that pleasure exerts its influence on all kinds of basic brain processes.
Far from being a heady, purely human pursuit, pleasure may be a very
simple and evolutionarily ancient invention.
Pleasure probably emerged for one simple purpose -- to guide actions. At
any one time an animal has all kinds of conflicting requirements: eat,
drink, stay safe, mate, get warm. And each is producing a motivation to
do something about it. "There must exist in the brain a common
currency that allows motivations to talk to one another," says
Michel Cabanac from the department of physiology at Laval University in
Montreal, Canada. "If there was not such a currency it would be
impossible to rank priorities."
Cabanac carried out a series of experiments trying to find out whether
pleasure is what allows us to prioritise our actions and carry them out
in the most efficient way. He compared all kinds of motivations: money,
pain, comfort, palatability and so on. "In all cases pleasure was
indeed the common currency that allowed the motivations to talk to one
another," he says.
In one experiment, Cabanac asked people to perform a climbing task on a
treadmill. The subjects had control of its speed or slope, and so could
decide how to complete the task -- climb fast and finish quickly, or
climb more slowly for longer. The way they made the decision was based on
pleasure, Cabanac says. They weighed up the discomfort in their limbs and
chest with the pleasure they would gain by completing the task. The same
happens when we choose what food to buy. People strike a balance between
the displeasure of spending money and the pleasure of eating palatable
foods. "If you combine the price with palatability you realise at
each instant [people] make decisions out of the algebraic sum of hating
to spend money, with loving to get good foods."
Decisions, decisions
We use pleasure to make all kinds of decisions, says Cabanac --
solving a mathematical problem, forming grammatical phrases, making
ethical choices, gambling. By showing people multiple-choice answers to
all kinds of questions or problems and asking them to rate how much
pleasure they felt reading each, he found that their ratings matched well
with the answers they subsequently chose. All decisions are made to
maximise pleasure, he says. We call it "gut instinct", but in
reality it is seeking pleasure. His ideas are backed up by the case of
Phineas Gage, a famous 19th-century patient who suffered brain damage to
his frontal lobes, leaving him unable to feel any emotion. Revealingly,
he was also unable to make decisions.
Clearly, though, humans are not slaves to instant gratification. We are
able to override the desire for immediate pleasure. But even this
decision can be viewed as one that ultimately maximises pleasure, because
only by deferring gratification can we gain the chance of long-term
rewards.
The fundamental role pleasure plays in decision making is leading some
researchers to see it as a basic biological process that evolved long
before humans did. Cabanac believes it arose somewhere between amphibians
and reptiles, while Damasio thinks even flies and molluscs can have
pleasure, if not the feelings associated with them. "Pleasure and
pain were the earliest forms of emotion to evolve," says Panksepp.
Our rich inner world of thoughts and feelings, and conscious awareness
itself, may all trace back to a simple sense of pleasure and
displeasure.
Unfortunately for the hedonists among us, the role that pleasure has in
guiding our behaviour seems to produce a natural limit. Pleasure, by
definition, cannot be long-lasting. It must switch off so that we can
move on to the next task.
By similar argument, we'll never achieve true happiness through the
pursuit of pleasure, says Cabanac, because we can never be truly
comfortable while we are in a pleasurable state. If we're experiencing
pleasure it's because we must need something. Take temperature. Only if
we're too hot or cold will we be able to experience the pleasure of a
cold drink or hot bath. Once our temperature has stabilised, we're
indifferent to either experience. If we are in no danger or need of any
kind, we're in a comfortable but indifferent state. "Pleasure --
sensory pleasure -- is not happiness, it is joy," says Cabanac.
"The state of indifference is what I call happiness."
New Scientist -- 11 October 2003
>>>>
Keith Hudson, Bath, England,
<www.evolutionary-economics.org>,
<www.handlo.com>,
<www.property-portraits.co.uk>
