november 2016 | Brain Check
Pleasurable Dopamine Rushes
Lars Olson is Senior Professor of Neurobiology at the Department of Neuroscience at Karolinska Institutet in Stockholm. He co-edited a book called Hjärnan, 500 pages of brain research he compiled together with his colleagues, and is a former member of the Nobel Assembly, a committee that selects the Nobel laureates in Physiology and Medicine.
What is a reward system and why do we have it?
“It’s a system that lies quite deep in the brain. It rewards us for the things that enable us to survive as individuals and a species. When we eat, drink, exercise and have sex, it feels enjoyable. The reward system is actually very complex. It connects with other parts of the brain like the cerebral cortex and involves several types of neurotransmitters. We tend to simplify things by referring to dopamine, which is the single most important neurotransmitter in the reward system.”
What is dopamine?
“A Swede, Arvid Carlsson, discovered dopamine as a neurotransmitter in the brain and it won him the Nobel Prize in 2000. He’s now in his nineties and is still active. Dopamine is of vital importance. It’s released whenever we feel something pleasurable and it makes us want more of the same. The reward system keeps rebuilding itself to make us crave more enjoyment.”
Will the reward system change over the next hundred years or so?
“No, a hundred years is nothing from an evolutionary point of view. The amazing thing is that this very old invention works so well and that we work so well considering how much our living conditions have changed.”
In your book Hjärnan you wrote: “When specific behaviour has been learned, the memory of that rewarding action remains in the brain and causes cravings for a similar experience.”
“The reward system alters itself so that we enjoy more and more of whatever it is that’s giving us pleasure. For example, amphetamine and cocaine are common in drug abuse and scientists know they cause the release of more dopamine than natural enjoyment does. This is why they’re so dangerous. The experience is so amazing the first time that the reward system thinks it’s what’s needed for survival and rebuilds itself. You become less and less interested in other types of enjoyment and more and more interested in the drug.”
How does the drug become the priority?
“The drug kidnaps the reward system. You also get strong recollections of the pleasurable event from the cerebral cortex. You have to sleep a few nights while the brain processes what has happened and decides what to save, after which the memories are stored. We remember things that are linked to the strongest emotions; positive or negative. With drugs it’s usually a positive memory and memories like that never disappear if they’re sufficiently strong. Ex-heroin addicts only need to pass by a place where they usually bought heroin or see somebody using it to want to start taking it again. Addiction should be seen as an acquired brain disease. If we rank the most common reasons for lost healthy years; which may be due to premature death or illness, first on the list is depression followed by alcoholism, which is also an acquired brain disease. We’re talking about huge social problems.”
Is it possible to rebuild the reward system to be free from addiction?
“Yes, there are two classic ways to escape addiction: have an experience that’s even stronger than the booze, or find a new love or salvation; a strong enough experience to help you put up a wall of resistance. There are also several medical treatments that are not used nearly enough, if I may say so. Then we should remember that if an alcoholic has been on the wagon for six months and falls off it for a weekend, all is not lost. It’s called a relapse and even people with high blood pressure and diabetes get them. The alcoholic knows they held out for six months and that experience should help them to remain sober. One common misconception is that it shows poor character and you should pull yourself together. However, there are very strong genetic factors that put certain people more at risk to become addicted to just about anything.”
Smoking is another common addiction.
“Nicotine is highly addictive. This is because it has an immediate effect. It reaches the brain at lightning speed. The shorter the time lapse between taking a drug and the positive kick it gives, the greater the risk of becoming addicted.”
Somebody once said that we don’t do much unless the reward system is involved. Is that right?
“Yes, for example, dopamine is important for walking. If you remove the dopamine from the brain, which you can do to a rat, it will always stay on the same spot. Parkinson’s disease eventually leads to immobility, and that’s because the dopamine neurons die. Generally speaking, you could say that if you turn down the neurotransmitters in the reward system then life would become very dull and grey. Eating would be no fun at all, in fact it would be difficult to enjoy anything.”
It’s not only enjoyment like winning that triggers the system, but also near wins.
“One-armed bandits are the work of the devil. When you win, the whole machine blinks, rattles and rings. It’s a very intense experience. The reward system goes into overdrive and activates different parts of the cerebral cortex. Near wins have been examined using a computer model of slot machines and functional magnetic resonance imaging of the brain. During the study, carried out in an MRI scanner, the test subjects sat in a reclining position playing on a screen. When three of the same symbol come up in a row, you win. A cherry comes up followed by one more. A third rolls slowly into view. If this last one gets slower and slower but stops just short, it’s called a near win. Addicts think they’re winning even when they’re losing. That’s the way the machines are designed. It turns out that near wins activate the reward system in exactly the same places as the wins, but not as much. Near wins are part of the strategy for getting people to continue playing, but there shouldn’t be too many near wins or the players will see through it.”
Does it activate the same parts as when taking drugs?
“Yes, the reward system activates and changes when gambling in the same way as when becoming addicted to drugs. There are studies from the USA based on the MRI brain scanning of cocaine addicts and non-addicts. Both groups were shown two videos: one with adult content and one with an addict fumbling with his cocaine and injecting himself. When the non-addicts saw the adult video their reward systems naturally activated, which is the purpose of it. They found it boring to watch the cocaine video, so the reward system didn’t activate. The result from the cocaine addicts was the other way around. They don’t get turned on by adult content anymore, but when they see a video about cocaine their reward systems activate. This clearly shows how cocaine has kidnapped the reward system.”
The reward system can also activate at the very sight of chocolate.
“The reward system activates even more for those who say they are addicted to chocolate and eat much more chocolate than others, compared with respondents who eat less chocolate and don’t see themselves as being addicted. When chocolate addicts see a picture of a chocolate bar, the reward system activates more for them.”
You write that computer games and virtual currency work in the same way.
“When you’re playing a computer game and are awarded virtual currency that you can use in the game, the reward system activates in the same way as it does for real money. The activation really steps up when you are a group playing an online game because you can show how clever you are, which is rewarding in itself.”
Does digital addiction develop in the same way as you described previously?
“Yes, and you can apply roughly the same criteria. You become more and more addicted to it and need an increasingly higher dose to get a kick. Everything else falls by the wayside; work, studies and close family. It’s the classic measure of dependence. Sometimes game dependency goes over the top. Men take out loans and falsify their wife’s signature to get money to feed their dependency. Computer game dependency can take on quite scary proportions. There are cases where despairing parents have had to contact social services to drag their sons (most of them are young men) away from their computers and convince them that they need to eat and sleep.”
I’ve read that it’s more difficult to get rid of digital dependency because it’s easier to get likes on Facebook than in real life.
“I’ve not studied that, but I wouldn’t be surprised if that were the case.”
A survey into the amount of time second and third-year law students in the USA spent on websites that were not relevant for their education showed that 58 per cent spent more than half their time on such websites.
“As a teacher I think I’d be somewhat disappointed.”
In his world-famous marshmallow tests, Walter Mischel shows that it’s not easy to delay rewards. In one of the tests, children are offered a marshmallow immediately, or two if they wait a while as the researchers left the room. In a new book he describes how children, who couldn’t resist the temptation, had to learn new strategies to delay the reward. One was to say quietly to themselves: “No, I’m not going to take it, I’m doing something else.” This would activate the child’s prefrontal cortex* first instead of the limbic system* and by repeating it enough times it would finally become automatic. The reward system is rebuilt and the child learns to delay the reward.
“I think there’s something in that. Parents and teachers have to lead by example in that case and stop checking their mobiles and chatting on Facebook all the time.”
What are the challenges faced by society, companies and organisations?
“That was not an easy question. Let me put it this way: I’ve come to the conclusion that anything you do or hear at a lecture has to be fun. If it’s fun then it takes off by itself; you want to hear it, you want to do the job. As a manager, you can provide both positive and negative experiences. But it’s so much better if they’re positive.”
What do you mean by fun? Should it be interesting or humorous?
“You have to be able to project your engagement to those sitting in front of you. Sometimes a person may come up to me and say they need to write a doctoral thesis as part of their career. I show them the door because it’ll never work out. You do it because you want to and because it’s fun.”
I interviewed Gunnar Bjursell, a colleague of yours at Karolinska Institutet. He said that motivation will be a vital issue in the future. How do you motivate people to carpool as an environmental consideration instead of driving by themselves? The reward system could play an important role here too, couldn’t it?
“The reward system is quite egoistic. You would have to be very educational in your approach to get people to enjoy using less fossil fuel and to recycle their waste better.”
* The limbic system is responsible for rapid decisions and is designed for fight-or-flight situations. The reptilian brain is part of the limbic system. As the prefrontal cortex takes more time and gives a broader and deeper picture, the child has time to learn from past experience and to consider future consequences. When the prefrontal cortex activates first, it is easier for the child to resist temptation.