by John Coates
THE PLEASURE OF INFORMATION
We are so completely enthralled by information that one could, without exaggeration, say we are addicted to it. The addiction develops under the influence of another neuromodulator, this one called dopamine. Produced by a group of cells at the top of the brain stem, dopamine targets brain regions controlling reward and movement. When we receive some valuable piece of information, or perform some act that promotes our health and survival, such as eating, drinking, having sex or making large amounts of money, dopamine is released along what are called the pleasure pathways of the brain, providing us with a rewarding, even euphoric, experience. In fact our brain seems to value the dopamine more than the food or drink or sex itself. Give an animal the choice between on the one hand eating and drinking, and on the other self-stimulating with dopamine, and it will self-stimulate until it starves. If noradrenalin modulates the brain’s overall level of arousal, how awake and attentive it is, dopamine modulates its level of motivation, how eagerly it wants things.
Unfortunately, dopamine neurons are easily duped, and can be tricked into bestowing their rewards by drugs of abuse. Almost every recreational drug, be it alcohol, cocaine or amphetamine, achieves its addictive effects by increasing the action of dopamine in a region of the brain called the basal ganglia, located midway between the brain stem and the cortex, and specifically in one part of it called the nucleus accumbens (fig. 8). If we view dopamine as the normal compensation we receive for valuable effort, then recreational drugs are in effect running a scam, tricking our brain into paying for healthy activities we never actually performed. To get an idea of just how effective this scam can be, consider the numbers. Food can raise an animal’s dopamine levels by 50 per cent, sex by 100 per cent. However, nicotine can raise them by 200 per cent, cocaine by 400 per cent, and amphetamine by 1,000 per cent. Give junkies the choice between food and self-stimulating with dopamine, and not surprisingly they too lose interest in eating.
It is tempting to conclude that dopamine is the molecule of pleasure, but unfortunately things are not quite that simple. When scientists tested this idea they found something they had not expected. If they gave an animal a shot of juice, say, they found that it experienced a spike in dopamine, just as you would expect if dopamine was coding for the pleasure of drinking. So far so good. But after giving the animal several more mouthfuls of juice they found something odd happening – the shot of dopamine in the animal’s brain started drifting forward in time, so that it actually occurred before the animal drank. The dopamine spike came to coincide with the appearance of cues, a sound perhaps, or an image, that reliably preceded the consumption of the juice. Put another way, the dopamine spiked when the animal received information predicting the imminent arrival of pleasure.
How, the scientists wondered, could an animal get pleasure before actually drinking? Some of them started to suspect that maybe there are two different types of reward – the pleasure of consumption and the pleasure of anticipation – and that dopamine has more to do with the latter. Other chemicals in the brain, such as natural opioids, may provide the pleasure of actual drinking, but perhaps dopamine provides something that is closer to a desire, even a craving. Desire is more of an anticipatory feeling; but is nonetheless powerfully motivating and in some sense enjoyable, although at times it can be more like a maddening itch. Two of the scientists conducting this path-breaking research, Kent Berridge and Terry Robinson, concluded that dopamine stimulates the wanting of juice rather than the liking of it.
In humans, dopamine works in much the same way, causing us to value cues that predict pleasure, cues such as the smell of our favourite restaurant, the exciting appearance off in the distance of ski slopes, or a certain form-fitting blue sweater worn on a date. Seen in this light, perhaps it is dopamine as well that drives our perennial obsession with money, the ultimate predictor of good times.
There is another wrinkle to the dopamine-as-craving story. Give a monkey a single squirt of juice and its brain shows a spike of dopamine, but repeat the process several times and eventually the dopamine neurons settle down. But now give the monkey two squirts when it expected one, and dopamine perks up once again. Give it three squirts and dopamine perks up even more. Yet if these three squirts are now repeated, dopamine once again settles back down. What this means is that the amount of dopamine released into the nucleus accumbens does not depend on the absolute amount of reward an animal receives, but on how unexpected it is. This further suggests that we enjoy and crave environments in which we receive unexpected rewards; in other words, we enjoy risk. Put another way, dopamine spikes with information; and it acts as a learning signal, making us remember what we have just discovered. Some neuroscientists, such as Jon Horvitz at Columbia and Peter Redgrave at Sheffield, have even gone beyond the dopamine-as-predictor-of-pleasure idea and controversially argued that any experience, even an unpleasant one, that helps us predict future sources of pleasure and pain can deliver a shot of dopamine.
Dopamine research has changed the way psychiatrists understand and treat drug addiction. Medical researchers have found that the brain chemistry of people taking drugs evolves along the same path as that of animals receiving juice. The drugs first deliver a pleasurable hit and a potent shot of dopamine, but with increasing use the dopamine signal drifts forward in time and attaches to cues predicting the taking of drugs – certain music, or people, or special places, such as a nightclub – and these stimulate a near-irresistible hunger. The really powerful motivation is now the craving of the drug rather than the pleasure it provides. Many addicts actually come to lose the pleasure they once enjoyed from drugs, may even find the actual consumption distasteful, but cannot stop. Smokers cannot resist the temptation to smoke, but often find the act itself a nasty one, leaving them feeling terrible afterwards. In order to kick a habit they now find unpleasant, addicts often find they have to separate themselves from drug-taking cues by changing neighbourhoods and avoiding old friends. Many anti-drug advertising campaigns have backfired by misunderstanding this point. These campaigns often featured images depicting the horrors of addiction, maybe a bloody syringe and a dark alley; but these images were the very ones predicting the consumption of drugs, and therefore delivered a large dopamine hit in many reformed addicts, perversely renewing their craving and driving them back to heroin or cocaine.
What else besides drugs of abuse can create a dopamine-driven craving? If dopamine fuels a desire for information and unexpected reward, perhaps it also fills us with a burning curiosity. Perhaps curiosity itself, the need to know, is a form of addiction, making us race to the end of a good mystery novel, or driving scientists to work day and night until they discover insulin, say, or decode the structure of DNA, scientific breakthrough being the ultimate hit of information. When the Theory of General Relativity dawned on Einstein, he must have had the mother of all dopamine rushes.
Gambling, with its unexpected rewards, can also become a dopamine-driven addiction. Plugging coins into a slot machine hour after hour may look the epitome of boredom, but when those three fruits line up unexpectedly and you hear that waterfall of coins, large quantities of dopamine are released into your brain, leaving you with a craving for more. And if gambling can be addictive, why not trading? Trading provides some of the highest rewards available in our economy, but they are highly uncertain, and attaining them entails predicting the future and taking huge risks. So it may be dopamine that delivers the powerful high traders feel when their trades work out. It is no wonder that many observers suspect that traders on a roll may be in the grips of an addiction. And like an addict who quickly habituates to a given dose of a drug and has to continually increase the hit, traders too may habituate to certain levels of risk and profit, and be irresistibly compelled to up their position size beyond what would normally be considered prudent.
Importantly, dopamine, like noradrenalin, does a lot more than motivate the brain: it also prepares the body for action. In the words of Greg Berns, a
neuroscientist from Emory University, ‘In the real world, action and reward go together. Goodies don’t just fall in your lap; you have to go out and find them.’ And it is dopamine that drives this search. That is what one research group from Germany found when they designed an experiment to disentangle the pleasure of eating from the desire to search for food. They pharmacologically depleted dopamine in rats, and found that the animals would continue to eat and enjoy food if it was put directly into their mouths, but would not walk even a short distance to obtain it.
When we look at this connection between movement and reward we glimpse the very motivational core of our being, what thrills us, why we take risks, why we love life. For dopamine does a lot more than merely tag information with a hedonic colouring; it also rewards us for physical actions that lead to unexpected reward, such as trying a new and successful hunting technique or stumbling on a particularly rich patch of berries when foraging in the woods, and it makes us want to repeat these actions. Indeed, under the influence of dopamine we come to crave these physical activities. As Berns says, research into dopamine has turned ‘upside down a basic tenet of economics’, for much of it has found, somewhat counter-intuitively, that animals prefer to work for food than to receive it passively.
A preference for effortful consumption makes sense from an evolutionary point of view, for both animals and humans. If you are programming an animal to survive, you should make it enjoy more than just eating and drinking and having sex, which would encourage it to develop into nothing more than a couch potato or a louche hedonist. You should make it love the activities that lead to the discovery of food, water and sex. And that is what dopamine does, it makes us want to repeat certain actions, be they hunting, going on dates, or for that matter searching the screens for a trading opportunity. A clear statement of this principle can be found, improbably, in the film Jurassic Park. When a group of visitors watch across an electrified fence as a goat is tethered to a stake, lunch for the resident T. rex lurking somewhere out of sight, Sam Neill comments ominously that this predator ‘doesn’t want to be fed. He wants to hunt.’
If we pull together the various strands of research on dopamine, we could say the following: that dopamine surges most powerfully when we perform a novel physical action that leads to unexpected reward. Dopamine drives us to push beyond established routines and to try new search patterns and hunting techniques. As a result, the effects of dopamine on the course of evolution have been revolutionary. According to Fred Previc, a psychologist at Texas A&M University, the rapid growth of dopamine-producing cells, the result of ancient dietary changes such as an increase in the eating of meat, changed history. It encouraged us to take risks just for the hell of it, independently of any rational expectation of gain. Dopamine fuelled a robust lust for life, with all its vicissitudes. You may well imagine just how fateful a day it was on the African savannah when the new dopamine-driven brain was given the keys to the mammalian body, with its awesome metabolic resources, for then humans evolved into what they are today – voracious and marauding search engines, Google on wheels.
John Maynard Keynes, more than any other economist, understood these subterranean urges to explore, calling them ‘animal spirits’ – ‘a spontaneous urge to action rather than inaction’. He considered them the pulsing heart of the economy. ‘It is a characteristic of human nature,’ he wrote, ‘that a large proportion of our positive activities depend on spontaneous optimism rather than on a mathematical expectation.’ Should this spontaneous optimism falter and animal spirits dim, leaving us with nothing but mathematical calculation, then, he warned, ‘enterprise will fade and die’. He suspected that business enterprise is no more driven by the calculation of odds than is an expedition to the South Pole. Enterprise is driven to a great extent by a pure love of risk-taking.
It is a core principle of formal finance that higher returns come only by taking greater risk, and much the same can be said of our ancient search and hunting patterns. Dopamine prompted us to try things we had not tried before, and in so doing led us to stumble upon valuable territories and hunting techniques that otherwise would have remained undiscovered. It pushed us to venture past protective barriers. ‘I have never been beyond the edge of the jungle. I wonder what it would be like in that wide-open savannah.’ ‘I wonder if a differently-shaped spear would work better.’ ‘I wonder what lies beyond the horizon?’ Even though answering these questions entailed great danger and resulted in countless deaths (in a very real sense curiosity does occasionally kill the cat), it nonetheless proved of great value in our long history of geographic, scientific and, yes, financial exploration. Dopamine, we could say, is the history molecule.
Mysteries remain in this intriguing molecule, and one in particular comes to mind. If dopamine fuels an almost addictive love of exploration and physical risk-taking, then what on earth has happened to it? Some 30 per cent of the American population is now obese and appears to have all but lost this drive, preferring inert consumption to effortful consumption. If dopamine has commanded such a powerful drive over our evolutionary history, launching us across the oceans and out into space, why is it now so easily dimmed? We do not yet have an answer to this question, although it remains one of the most pressing issues for medical science. But an intriguing suggestion can be found in some almost-forgotten research conducted in Vancouver in the 1970s, research that came to be known as ‘ Rat Park’. The seventies were a time when many of the laws governing drugs of abuse were introduced, and the lead author of the study, Bruce Alexander, questioned the logic behind the then-current understanding of addiction.
What he did in his study was place rats in a bare cage with two bottles they could drink from, one of which contained water, the other water laced with morphine. Not surprisingly, the rats preferred the bottle laced with morphine, and in time they became addicted to it. What Alexander did next was interesting. He repeated the experiment, only this time he placed the rats inside what he called Rat Park, a cage with a running wheel, foliage, other rats, both male and female, and so on. In other words, he provided the rats with an enriched environment. When placed in Rat Park the rats did not prefer the morphine-laced water, and did not develop an addiction. In light of later research we could speculate that these rats were getting the daily dopamine hit they needed just from normal forms of search, work and play. Indeed, recent research has found that an enriched environment is such an attractive alternative to drugs that animals addicted to cocaine, once returned to an enriched environment, will actually kick their habit.
Rat Park provides a novel perspective on our current problems of addiction and obesity. It leads us to wonder, have we denied broad swathes of the population an enriched environment? Have we denied them access to sports facilities? To artistic, even scientific, training? To green spaces? Has something gone wrong in the workplace? With urban development? Have we in effect removed large numbers of people from Human Park, and placed them in an empty cage? These are burning questions, because the obesity epidemic, besides being a medical catastrophe, may be dimming the gut feelings and entrepreneurial drive upon which our prosperity and happiness depend.
THE ANNOUNCEMENT
By 1.30 p.m. the market has recovered half its lost ground, with the ten-year Treasury now down only three quarters of a point. Gwen has made back all the money she had lost on her five-year position, and she and Martin have emerged, sure enough, with a tidy profit, amounting to almost $3 million, on the long positions they built up when the market hit its low point. Gwen has her mojo back. No way is she going to be transferred anywhere. (Martin has been reassuring her, saying that Ash is fixated on problems on the mortgage desk, not her.) Gwen and Martin decide to sell out half their positions, reasoning quite rightly that it is not wise to have a large position, long or short, going into the Fed announcement. The rest of the traders have also done well, and the desk now clicks as an experienced team. A mood grows, a happy contagion, a silent complicity. Communication reduces to the occas
ional half-sentence and monosyllabic affirmation.
A hint of danger may linger in the market, but most traders welcome it, and a slow burn of excitement and quiet confidence prepares them for the Fed announcement. The rumour had been unexpected, the sell-off a complete surprise, but Martin and Gwen have risen to the challenge and surprised themselves with a good profit. These are precisely the circumstances that trigger a surge of dopamine, and this narcotic drug, now flooding their brains, gives Martin and Gwen an incomparable thrill.
The challenge they face is, however, more than an intellectual puzzle. It is a physical activity that demands skill, quick reactions, and metabolic and cardiovascular resources sufficient to support their efforts. So, as the full import of the rumour sinks in, Martin and Gwen’s heart rate and breathing speed up, their blood pressure increases, and crucially, stress hormones flood into their blood. Adrenalin releases glucose from the liver, and cortisol energy stores from liver, muscles and fat cells, so that Martin and Gwen have ample fuel supplies to carry them through the afternoon. The cortisol is especially potent, for it freely enters the brain, finds receptors all along the pleasure pathways, and magnifies the effects of dopamine. Physical stressors, like a fast drive, off-piste skiing, or trading an exciting market, provide a thrill not usually expected from a stressor. But at low levels, cortisol, in combination with dopamine, provides a narcotic hit that is nicely described by the neuroscientist Robert Sapolsky as intense stimulation – ‘ You feel focused, alert, alive, motivated, anticipatory’ – and by Greg Berns as a profound feeling of satisfaction.