Dopamine doesn't do what you think it does — The Neuroscience Review

Skip to content

Dopamine's pathways. The mesolimbic and nigrostriatal tracts, running from the VTA and substantia nigra, carry most of what people mean by dopamine. Slashme, Patrick J. Lynch, and Fvasconcellos, CC BY-SA 4.0.

Key takeaways

Dopamine isn't the brain's “pleasure chemical.” It signals reward prediction error , the gap between what you expected and what happened.

It drives wanting (the motivation to pursue), not liking (the pleasure itself), which depends on other systems.

“Dopamine detox” is mostly a myth. Dopamine isn't a finite resource, and chronically low dopamine looks more like Parkinson's than calm.

If you've spent any time on the internet, you've absorbed a particular story about dopamine. It goes like this. Dopamine is the brain's reward chemical. When you eat something delicious, scroll Instagram, take a drug, or accomplish a goal, your brain releases dopamine and you feel pleasure. Things that release a lot of dopamine, like phones, sugar, and drugs of abuse, are addictive because they keep flooding the reward system. The solution, apparently, is a "dopamine detox."

Almost every part of that story is wrong, or at least seriously misleading. Here's what dopamine actually does, what the research has shown for decades, and why the slop version matters.

The basic picture

Dopamine is a neurotransmitter, one of the chemical signals neurons use to talk to each other. The neurons that release it are concentrated in two small structures deep in the midbrain, the substantia nigra and the ventral tegmental area . From there, their axons project widely into the rest of the brain, including the striatum, the prefrontal cortex, and the limbic system.

Dopamine is involved in many things, including movement (Parkinson's disease is essentially the death of dopamine neurons in the substantia nigra), executive function, hormone regulation, and, yes, reward. But the word "reward" is doing a lot of work in that sentence, and unpacking it is where the popular story starts to fall apart.

The Schultz experiments

In the 1990s, the neuroscientist Wolfram Schultz and his collaborators ran a series of experiments on macaque monkeys that fundamentally changed how the field thought about dopamine. Their setup was simple. A monkey was given a reward, a drop of juice, at unpredictable intervals. Schultz recorded the activity of individual dopamine neurons during the experiment.

The naive prediction, if dopamine equals pleasure, would be that dopamine neurons fire when the juice arrives. They did. But that wasn't the only time they fired.

When the experimenters started preceding the juice with a predictable cue (a light or a tone), dopamine neurons stopped firing when the juice arrived and started firing when the cue appeared. The neurons had shifted to responding to the prediction of reward, not the reward itself.

More striking still. If the cue was presented and the juice was not delivered, dopamine activity dropped below baseline at the moment the juice should have arrived. The neurons were signaling not "pleasure" but something more like "this is better than I expected" or "this is worse than I expected."

This is now understood as a reward prediction error . Dopamine neurons aren't measuring how good something feels. They're measuring the gap between what you predicted would happen and what actually happened. Better than predicted, dopamine fires. Exactly as predicted, roughly baseline. Worse than predicted, activity dips.

Wanting vs. liking

A parallel line of research from Kent Berridge's lab at the University of Michigan pushed the picture even further. Berridge showed, in rats, that you can pharmacologically dissociate two things the casual "pleasure chemical" framing lumps together.

He called them wanting and liking . Wanting is the motivation to pursue a reward. Liking is the actual hedonic experience when you get it. Berridge's work showed that dopamine is required for wanting, but not for liking. Rats whose dopamine systems are destroyed will not seek out food. Left in front of a meal they will not eat it either, and will starve unless they are fed by hand. But put a drop of something sweet in their mouths and their facial reactions (a measurable index of hedonic response in rodents) stay completely normal. They have lost the wanting, not the liking.

In other words, dopamine isn't the pleasure itself. It's the motivation to chase what your brain predicts will be pleasurable. The pleasure itself (the "liking") seems to depend on different systems, involving opioid and endocannabinoid signaling.

Enjoying this? Get one neuroscience deep-dive in your inbox every Wednesday.

Subscribe

Why this matters

A lot of the popular pseudo-science about dopamine collapses once you get this distinction right.

"Dopamine detox" (the idea that you should fast from stimulating activities to "reset" your...