Hey there. It's Dr. Susan Peirce Thompson, and this is the second of three vlogs in a row that are going to talk about some foundational neuroscience that helps explain the role of dopamine in the brain. Today I want to talk about the fact that dopamine is all about wanting, not liking. It's not pleasure. It's not pleasure. And I want to open this up by just saying, I have spent so much of my life, not lately, thank God, sitting in my car, shoveling in food that I wasn't even enjoying eating. I can remember so many times sitting there eating like a machine, sometimes with tears streaming down my face, sometimes just numb, sometimes actively thinking, this doesn't really taste good at all, but I'm still doing it. Why am I still doing this?
I still wanted it, but I definitely wasn't liking it. What happens as the addict moves further down the path of addiction is that their experience of wanting something and liking it starts to diverge more and more and more. I'll never forget how I felt and what I was thinking after the first night that I smoked crack cocaine. I was 19 years old. My manager at a movie theater where I was working, free-based cocaine, and I convinced him to teach me how to do it. He resisted, resisted, resisted, resisted, resisted, and then gave in. I went over to his trailer, he taught me how to cook up cocaine into crack, and I smoked all night and I was biking back to my mom's house where I lived, and I remember thinking, "Well, I did it. I freebased cocaine. I smoked crack all night, freebase, and cracker." They're not exactly the same thing. Actually, I was smoking crack. It wasn't freebase. Technically, freebase is made with ammonia. This was made with baking soda. I was smoking homemade crack is what I was doing. But back in the day, people used to call that freebasing. Whatever. Same. Same. So, I'm biking home and it's like four or five in the morning. And I'm thinking, you know what? I just did that. And I will never get addicted to that because it just wasn't that good. I just didn't like it that much. I was clear that first night I didn't really like that much at all. It was all right. Nothing to write home about.
I had no idea that addiction is not about liking something. The brain still wants it. With food, I can't tell you how much the divergence of liking and wanting ruled my life. As a matter of fact, I remember thinking when I was in a relapse with food, I always seemed to pick food that I didn't like hardly. I just didn't like it that much. All the foods that I really, really liked, I never seemed to get to eat because my eating in relapse was all driven by when can I sneak and get it? Where can I get it from? Who's watching or not watching? How can I get away with it? And my brain was just doing this calculus of how can I get the biggest hit and get away with it? I always ended up grabbing foods that weren't necessarily the foods that I liked. It's just that's what my brain wanted at that time, and then figuring out how to hide and go eat it. It always felt like I'd watch everybody else eat the good food, the food I really liked, but I wasn't going to do that in front of them. Then I would end up driving past a gas station on my way home and go in and just buy the best thing I could find, which was nowhere near as good as the food I'd already seen all of them eat, and I'd shovel it in and not really like it and just get my hit.
Anyway, so what's the science of this? How do we know that dopamine is not about pleasure, it's about wanting? It's not about liking, it's about wanting. First of all, it was James Olds and Peter Milner. James Olds was a postdoc in Peter Milner's lab at McGill University in 1954 in Montreal, Canada. They weren't trying to study addiction at all. They weren't even trying to study any of this stuff. They were trying to study arousal in the reticular formation, but their hand slipped a little as they put the electrode into the brain of this rat and they put it into the septal area instead of the reticular formation by mistake, and they innervated the septal area. Where's the septal area? Well, it's in the addiction center of the brain. It's right by the nucleus accumbens and the ventral tegmental area. So they stimulate this area of the brain. what they noticed was this rat from then on over and over and over and over again, would run back to that corner in the cage where that had happened, where it had gotten stimulated that way, as if it was saying, "More please. Can I have that again?" It was such weird behavior that Olds and Milner made a contraption where the rat could press a lever to deliver a slight electrical stimulation to its own brain. An electrode was in that area of the brain and the rat could just press the lever and get that stimulation. The rat pressed it over and over and over and over and over and over and over and over and over and over. Thousands of times an hour, the rat didn't eat or sleep or the rat ignored females in heat right next to him, didn't care, no sex, no thank you. Just let me press this lever and get my fix.
Now, what James Olds and Peter Milner thought was that this showed pleasure, that the rat was self-pleasuring. It was James Olds who wrote a scientific American article in 1956 called The Pleasure Centers in the Brain. That's what popularized the concept and that's what stuck. It seemed like these rats liked to self-pleasure and that this felt good to them.
Now, by the late 1970s, this theory had advanced and seemed even more likely. Roy Wise had done studies and had come up with the anhedonia hypothesis of dopamine. So, they'd figured out how to selectively block dopamine in the brain. Under those conditions, rats wouldn't even go get food. They were so listless that they wouldn't go get food. What Roy Wise and his colleagues assumed was that this meant that they weren't getting any pleasure anymore from food, so it wasn't worth it to go eat the food. This sort of cemented or reinforced this idea that dopamine is a pleasure chemical and it makes you like things. It makes things pleasurable. It makes things worth having or doing, right? You've probably heard of this idea that dopamine is a pleasure chemical. It's been very persistent, even though it was debunked a long, long time ago.
How did it get debunked? Well, this guy named Kent Berridge at the University of Michigan did a series of studies starting in roughly 1989, ultimately ended up doing them with rats, with monkeys and with humans. The foundation of it was the taste reactivity test. At this point, it had been discovered that certain tastes in all kinds of mammals, including rats and monkeys and humans, produce characteristic facial expressions. Sweet tastes produce a protruding tongue and like a lip smacking behavior. So, someone's kind of going, right? Bitter tastes, in contrast, produce an arm flailing. It's like a wince, a pullback, and arms like hands flailing like ew, like ah, like a shaking, flailing thing. And so, with these facial expressions, you can kind of tell when an animal or a person is liking something.
What Kent Berridge did, is he did experiments selectively blocking dopamine and he showed that animals, including humans, won't go get food if their dopamine is blocked. But if you put the sweet taste on their tongue, they still like it. They still show the lip smacking and the tongue protruding and the, that's good. They like it, but they don't want it anymore. They won't exert any effort to go get it. Similarly, if you enhance dopamine in the brain, they want it more. They will hustle faster to go get it, but the taste expression doesn't show any increase at all, which normally it would. If you like something more, if it's a better sweet taste, you lip smack and more. And so, when you enhance dopamine, people will run and animals will run to get the sugar, but then once they get it, they don't like it anymore.
Over this long series of experiments, Kent Berridge's work showed that wanting and liking are completely divergent experiences and that it's wanting that is mediated by dopamine. It turns out that liking isn't mediated by dopamine at all. It's mediated actually by internal opioid receptors. So, you've got these endogenous opioids. Yeah, opioids like heroin, like opioids, morphine, you have them inside your own brain made by you. That's what stimulates liking. Now, as a food addict experiences this, so as someone whose brain is getting more sensitized to sugar flour concoctions and foods that are hyper palatable drive through convenience store type foods, here's what someone's going to experience. They start eating sugar and flour foods, they get exposed to donuts and all those things, and the dopamine receptors in the addiction centers in the brain, they down regulate. I've been telling you about this for 12 years now, right? It's a solid phenomenon. What happens now is that the brain wants more. The brain wants more. It's called a craving, and cravings start to intensify, but meanwhile, the liking system isn't getting any more out of it. As a matter of fact, what's happening is the opposite for the liking system. Those opioid receptors are getting overly hit on and they don't like it. They get overly sensitized and they start to shut down. They're like, "Oh no, thank you. I don't want anymore. I don't like this anymore. Yeah, no thank you." So, the wanting gets bigger and the liking gets smaller. In fact, the liking system is very fragile and diffuse and scattered around. Those opioid receptors are in tiny clusters and they're kind of in lots of different spots. The wanting system is central, it's massive, and it gets bigger really easily.
You could think of the wanting system as a massive bonfire and the liking system is a little candle that gets blown out really easily. The bonfire gets bigger and bigger and bigger. The candle just blows out and you end up wanting, wanting, wanting, but not liking, liking, liking. Okay. So, here's the good news. You start doing Bright Line Eating®. Research out of my lab shows that it takes about eight weeks for cravings to subside massively. In other words, going from moderate to high craving levels down to really, really low craving levels in just eight weeks. We can presume a measure of dopamine replenishment in the nucleus accumbens and the ventral tegmental area, the central areas of the brain that we're talking about here. This means that wanting comes down. Wanting comes down. Meanwhile, that liking candle that got blown out so easily, as you ease up on the intensity of the foods and the frequency with which you're overstimulating those receptors, the liking reignites and actually grows quite a bit. What you find is you start liking your Bright meals a lot more and you don't want anything but them anymore, in part because of the reward prediction error that we talked about last week.
You can watch last week's vlog, but basically in this case, the cue that predicts your Bright meal is coming starts to feel really engaging for your brain and it pulls you into your seat to eat your lunch. You eat the lunch. It satisfies, and hooray! But the liking and wanting systems start to recalibrate pretty quickly, like in the first couple of months of doing Bright Line Eating and meals that used to maybe feel hard to eat start to feel rewarding, start to feel good enough, start to feel better than good enough, surprisingly good. From last week's reward prediction error, that meal that's better than expected starts to deliver some extra dopamine and that's really nice. That makes you want the next meal and it becomes a virtuous self-rewarding cycle in the brain.
Lastly, I would say just be careful about the cues because wanting is all triggered by cues. What that means is that if there's a time of day or a site or a logo or some packaging or something that's going to remind you of foods that you used to eat, those cues are going to pull your wanting system. The more you can eliminate those cues, the better. If you live at home, be vigilant with cleaning out your kitchen. Get rid of all the foods that might trigger you. If you work somewhere where they've got a break room that's going to have sugar stuff in it, don't go there anymore. Go outside to a picnic table to eat your lunch. The more you can do to reduce the cues that are going to trigger your wanting system, especially early in your Bright Line Eating journey, the better off you're going to be. So, wanting, not the same as liking. Dopamine is not a pleasure chemical. It's a wanting chemical. That's the weekly vlog. I'll see you next week.
