Here is the full text of paleoanthropologist Daniel Z. Lieberman’s talk titled “Dopamine: Driving Your Brain into the Future” at TEDxWilmingtonWomen conference.
Listen to the MP3 Audio:
TRANSCRIPT:
Your brain is a funny thing. Sometimes it does what you want it to do, such as composing email or find something to eat in the refrigerator.
Other times, it’s uncooperative and obstinate, refusing to get started on that important new project, or getting stuck and ruminating all day long on some negative thought that makes you feel unhappy.
Your brain is brilliant and rebellious; it can be your best friend and sometimes your worst enemy.
The first step in taming this beast and getting out of it all that you can is to understand it. And today I’m going to tell you an important secret about how the brain works.
And oddly enough, it starts with the seemingly simple distinction between up and down.
So just for a moment, let me ask you to look down and what do you see? You may see your hands, maybe a pen, cup of coffee, possibly a cellphone.
When you look down, you’re looking to what’s called the peri-personal space. That’s a space around you that’s within arm’s reach. Things that are within the peri-personal space are typically things you own and control. You use them, enjoy them, sometimes consume them.
When you look up, on the other hand, you’re looking out into the extra personal space. The world that’s outside your arm’s reach.
If you want or need something in the extra personal space, it’s going to take effort to get it. It could be a small amount of effort walking across the room to pick up a book off a table or it could be more. Walking to the store to buy a bag of peaches, or planning a trip around the world.
Interacting with things in the extra personal space takes place in the future, because those things aren’t here.
When our brain processes things in the peri-personal space, it uses a handful of chemicals that might be called the here-and-now brain chemicals, because they process things that are right here in the present moment.
When we look out into the extra personal space, into the future, the imaginary, the abstract and unreal, our thoughts are coordinated by one single brain chemical. And that’s dopamine. It’s the chemical of what you desire.
Now that raises a question: Why is it that evolution created these two very different pathways, one for what we have and another for what we don’t?
And the answer is pretty straightforward. To our evolutionary ancestors, the familiar saying: either you have or you don’t could very easily become if you have it, or you’re dead.
From a survival point of view, and your brain is a highly tuned survival machine, there’s a fundamental difference between resources you have, resources such as food, water, reproductive partners, and those that you don’t. And sometimes that difference was the difference between life and death.
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Now when we interact with things that we have, we engage in consummatory behaviors. And that, of course, we refer to consuming: eating and drinking, but also refers to consummation.
What happens at the end when we reach our goal, the feeling of fulfillment and satisfaction that we’ve earned?
When we interact with things that we don’t have, we engage in appetitive behaviors: desire, motivation, and hard work.
So let’s start out by taking a look at some of the here-and-now brain chemicals that you may be familiar with.
What gets processed in the here and now? All sensory experiences: we see, hear, taste, touch, smell, right here in the present moment. And emotions are the same. We feel joy, pleasure, and sadness, right here in the present. The same is true with social interactions. We experience empathy, warmth and just the joy of being with people we love in the present.
That’s the here and nows.
What about dopamine? What do we know about dopamine?
Much of the early research that was done on dopamine was done by addiction researchers. And that’s because this is the brain chemical of desire and motivation. And people who are addicted are desiring and are motivated to get toxic chemicals that are destroying their lives.
So in this study, the scientists injected volunteers with intravenous cocaine, and then measured the activity of a structure in their brain called the striatum. It’s a part of the brain that’s rich in dopamine activity. Red and yellow represent high levels of activity, and blue and green represent lower levels of activity.
What you can see is that cocaine is a powerful stimulator of dopamine. A few minutes after the drug is injected, levels spike way up and then as the body clears the drug, they come down.
Now the scientists were not only interested in the objective measurement of brain activity, they also wanted to know about what their research volunteers were feeling. They wanted to know about the subjective experiences they were having.
So at each point in time they asked them to rate the level of euphoria they were experiencing. And that’s represented by the gray bars to the right of each scan.
What immediately jumps out at you is this very tight, very close relationship between dopamine activity and the level of euphoria.
Based on this study, and others like it, the pathway that dopamine cells take through the brain was named the reward pathway.
The reward pathway… and dopamine was christened the pleasure molecule.
And this makes a lot of sense. Dopamine rewards us when we do things that make our evolutionary success a little bit more secure. When we get food when we’re hungry, when we win a competition, score the goal in the soccer game, all of these things make our future a little bit more interesting and perhaps a little bit more secure.
And if you’ve heard of dopamine, as many of you have, this is probably the context in which you’ve heard of it: as the pleasure molecule. And as I said it makes a lot of sense. There’s only one problem, and that is that it’s wrong.
It turns out it’s a little bit more complex and a lot more powerful. So subsequent researchers reasoned: it’s very unlikely this circuit evolved to respond to cocaine, it’s a lot more likely evolved to respond to natural rewards, such as food.
So they designed an experiment in which they dropped pellets of food into a rat’s cage and then measured the dopamine response in its brain.
On this graph, we see a few seconds of time, and each dot represents an individual dopamine cell in the rat’s brain becoming activated. The bars along the top represent the total number of dopamine cells that are active at each point in time.
All right, so we got the vertical line, we drop a pellet of food into the rat’s cage. And a moment later we get a spike in dopamine firing. So far so good: the pleasure molecule.
But look what happens next. Look what happens if day after day we continue to drop pellets in the rat’s cage at the same times every day, we train the rat to expect the rewards and the dopamine signal disappears.
Now the rat is devouring the pellet of food with just as much apparent pleasure as ever but the dopamine response is gone. Why? The answer is that dopamine is not the molecule of pleasure. Dopamine is the molecule of novelty.
Only unexpected rewards trigger dopamine. The scientific term for this is reward prediction error. As we go through life, we’re constantly making predictions about what the future holds, particularly with regard to rewards. You open up your wallet expecting to see $40 and there’s $60 in there. You just made an error with your reward prediction and you get a little spray of dopamine.
Let me give you another example. You’re walking down the street on the way to work. You’ve walked down the street dozens of times before, nothing has changed, and your dopamine system is at rest. All of a sudden, you realize a brand new bakery has just opened up… bang! Dopamine! Your future just got a little bit more interesting.
So you walk in, order croissant cup of coffee, delicious, you decide that from now on you’re going to come here every day for breakfast.
And then what happens? Two weeks later, you’re sitting in the bakery chewing on your croissant… nothing. Your thoughts are elsewhere, all the enthusiasm, the excitement that was first there is now completely gone.
We can express this through a simple mathematical formula: Dopamine release = the actual reward – the expected reward.
When the bakery was a surprise, your dopamine system responded fully. As expectation came up dopamine went down. And it’s not just bakeries and croissants, this happens with getting a raise, getting a promotion, buying a big-screen TV, even falling in love. And that stinks, because dopamine feels so good.
We all particularly love dopamine. We like new things, we like to think about the future. We love ideas. But as soon as what we hoped for becomes what we have, dopamine disappears.
Does that mean that we are destined to forever chase things and as soon as we catch them, they slip through our hands? Not exactly.
But if we want to get satisfaction from the things that we have, we’ve got to shift down. We’ve got to come out of our dopamine circuits into our here and now circuits. And they feel different. It’s a little bit more of a touchy-feely experience that is not always comfortable for people who love dopamine.
But dopamine can’t give you satisfaction any more than a hammer can turn a screw. Dopamine can only say: more. That’s what dopamine is for. To maximize future resources, whether it is the passion, patience, perseverance and hard work necessary for scientific discovery, buying a new home, or starting a new career, dopamine is there to deliver. Dopamine changes the world. It makes the world a better place.
But if we’re not careful, it can also destroy us.
On July 20th 1969, Buzz Aldrin walked on the moon. It took a whole lot of dopamine to get him there. But based on what we know about his life, it seems like he had a lot of it. So much in fact that it may have crowded out pretty much everything else.
When he returned to Earth, a reporter asked him: What did it feel like to walk on the moon? Buzz Aldrin replied: “Look, we don’t know we were feeling. We weren’t feeling.”
What were your emotions as you walked on the surface of the Moon? Fighter pilots don’t have emotions. He told a group of admirers: walking on the moon was just something we did. Now we should do something else.
But how do you top walking on the moon? If you’re all dopamine all the time, that becomes a very important question.
You might be able to guess what happened next. He started drinking a lot. And a short time later he became an alcoholic. He married and divorced two women, and eventually things got so bad he was hospitalized on a psychiatric inpatient unit.
He recovered. And he went on to do more extraordinary things. But for a period of time, that same chemical that lifted him up into the heavens made his life a kind of hell.
So if you want to do great things, fire up your dopamine circuits: Desire change, look to the future, motivate yourself, cross bridges and succeed.
But when you get there you need to do something else… something that for many of us is going to be just as difficult: you need to turn off your dopamine circuits. Let your hear-and-now circuits have their way and celebrate your success. Connect with family and friends and if only for a little while, remember to spend some time right here in the present moment.
