Neuroscientists have questioned the classical theory of how dopamine works in the brain

The classical theory of dopamine, one of the most recognized models in neuroscience, has come into question. New research shows that this neurotransmitter performs functions in the brain that go far beyond regulating pleasure and reward. This was reported on March 17 in the journal Nature.

Dopamine has been considered a "pleasure chemical" for decades: It has been associated with a sense of reward when browsing social media and other sources of pleasure. Neuroscientists admit that this idea is a gross simplification, but until recently they relied on a coherent scientific model that explained the mechanism of its operation.

The classical concepts are based on the hypothesis of the reward prediction error (RPE). According to her, dopamine releases link stimuli with rewards, helping the brain form and refine expectations. The theory was formulated in 1997 based on experiments with primates: a neuroscientist from the University of Cambridge, Wolfram Schultz, showed how the activity of dopamine neurons changes as a monkey learns to anticipate a reward. First, the neurons reacted to the unexpected receipt of juice, then to the light signal preceding the juice. If the expected reward was not received, the activity of the neurons decreased.

"Dopamine was an area of neuroscience where we had a computational model that explained both the signal and what it was calculating," said Mark Humphries, a neuroscientist at the University of Nottingham.

The Inner Darkness: what problems prevent people from living

Why do bad thoughts destroy the psyche and set you up for failure?

About 10 years ago, experimental methods appeared that made it possible to more accurately track the release of dopamine in the brains of animals. New research has shown that dopamine neurons respond not only to rewards, but also to threats, new stimuli, movement, and social behavior. A number of studies have documented that individual subgroups of dopamine neurons encode the animal's position in the maze or the speed of its movement, rather than the value of the goal.

The 2025 study showed that dopamine is involved in predicting actions and promotes their repetition, meaning that repetitive or addictive behaviors may be shaped differently than RPE suggests. Erin Calipari, a neuroscientist at Vanderbilt University, has found that dopamine is released in mice in response to stressful stimuli, including mild electric shocks.

Vijay Mohan Namboodiri, a neuroscientist at the University of California, San Francisco, has proposed an alternative model that actually reverses the logic of RPE. According to his version, an animal, having received a reward, looks for its cause in the past, and does not expect it, focusing on the previous signal. Experiments with mice given sweet water at random times confirmed his hypothesis: dopamine activity increased as the experiments were repeated, rather than decreasing, as RPE would have predicted.

The discussion goes beyond academic. RPE underlies the clinical concepts of attention deficit hyperactivity disorder, schizophrenia, and addiction. If the model turns out to be incomplete or erroneous, approaches to the treatment of these disorders will also be affected.

Pill fashion: Russians are buying antidepressants more often

Doctors told us how to distinguish mental disorder from nervous exhaustion.

On March 11, Medical Xpress reported on the association of changes at the cellular level with fatigue in depression. Researchers have found that cells in people with depression produce more energy molecules at rest, but have a reduced ability to increase energy production under stress. According to the scientists, this indicates the ability of cells to work with overload in the early stages, which can lead to long-term problems.

All important news is on the Izvestia channel in the MAX messenger.