The concept of the dopamine reward prediction error is important for understanding the roots of learning, motivation, and even addiction. It’s all about how our brains respond to rewards (and how we get bored with the same reward over time).
What’s the point of dopamine?
Dopamine is a neurotransmitter (or “chemical messenger”) that plays a role in our brains’ reward system. In other words, it’s the star of the show when it comes to feelings of pleasure and satisfaction.
Think about how you feel when you sit down to your favorite meal. Or approach the counter with a long-sought item you saved up money to buy. Happy times! Right?
Well, one particularly interesting (and, frankly, kind of unfair) element of how dopamine functions is that once we already know what a reward will feel like, our brains don’t send out as much dopamine. This is the concept of the dopamine reward prediction error.
What is the dopamine reward prediction error?
Let’s dive a little deeper.
Imagine you’re at a new restaurant for the first time. You order a dish you’ve never tried before. To your pleasant surprise, it turns out to be delicious. Your brain rewards you with a burst of dopamine, creating a sense of pleasure and satisfaction. In essence, your brain is saying, “Good job! Let’s remember this for next time.”
Now, let’s fast-forward to your next visit to the same restaurant. You order the same dish, this time expecting it to be tasty. But here’s the catch – when you take the first bite, your brain’s dopamine release is less intense than the first time. This is because the pleasure derived from the meal was expected. This concept is known as reward prediction error.
Even when you’re eating your favorite meal, it may never taste as marvelous as the first time you had it.
What’s going on in the brain when there’s a dopamine reward prediction error?
Reward prediction error is your brain’s way of comparing the predicted reward (expectation) with the actual outcome. When reality exceeds your expectations, a positive prediction error occurs. And your brain increases its dopamine release.
Conversely, when the actual reward is less than expected (as so often happens in life!), a negative prediction error occurs. Few things are as good as we imagine them to be, and this results in a decrease in dopamine release. (Why did our brains stop playing nice?!)
Why is your brain being a jerk about dopamine?
This dopamine release mechanism seems to play a role in how we adjust our predictions based on outcomes. Technically, it helps us learn from our mistakes and successes. But clearly, it’s not all fun and games. Your brain doesn’t give you a trophy every time you do something good (at least not a big one).
This dopamine-driven learning process can be exploited in harmful ways too. Just think about addiction.
Some drugs generate a significant positive prediction error in our brains. In other words, we take them and (if we survive) we may get a massive release of dopamine that makes us feel great. But this tricks the brain into overvaluing the substance. And this can drive intense cravings and compulsive behavior.
The down side of dopamine
Whether it’s drugs or food or destructive behavior, repeated exposure leads to a decrease in the dopamine response. Unfortunately, this means our bodies require more of the substance to achieve the same effect. That’s addiction.
But here’s the good news – understanding the way our brains respond to reward prediction errors can open up possibilities for new therapeutic approaches. It is helping researchers develop interventions that ‘retrain’ the brain’s reward system to reduce the impact of negative prediction errors and boost our ability to learn from positive experiences.
Source: “Dopamine reward prediction error coding” — Dialogues in Clinical Neuroscience
