Cocaine does not build new bad habits in the brain. Instead, it steals the good ones. But a new study shows that cocaine hijacks brain circuit pathways that normally control simple mouth and face movements. It twists this healthy system into a loop of compulsive repetition. So the finding may change how scientists understand addiction.
The research comes from the Hebrew University of Jerusalem. Current Biology published it on September 22, 2026. PhD students Ben Jerry Gonzales and Itay Shalom led the work under the supervision of Prof. Ami Citri. As BFHU reports, they also used a custom deep learning system called STEREO to watch the entire behavioral world of mice on video.
Healthy mice are curious. They explore, sniff, groom and walk around. But after repeated cocaine exposure, their rich behavior collapsed. By the fifth day, the mice spent more than 60 percent of their time licking the floor and walls of their enclosure. Yet the mice almost never behaved this way without the drug.
The team traced this change to the ventrolateral striatum, a small brain region that manages mouth and tongue movements. This area holds two opposing pathways. Think of them as a brake and an accelerator for actions. Cocaine pushes the accelerator and weakens the brake. As a result, the mind gets stuck in one repeating loop.
The experiments were striking. When researchers activated the indirect pathway, the brake, cocaine driven licking stopped at once. The mice returned to normal varied behavior. Still, when the stimulation ended, the compulsive licking came back. Silencing this pathway made the rigidity worse.
The direct pathway, the accelerator, told the other half of the story. Calming it down weakened the drug induced behavior. And switching it on in healthy mice with no cocaine was enough to create the same rigid repetitive patterns. Yet once the team pushed the circuit, the drug itself became unnecessary.
“Cocaine does not appear to create an entirely new behavioral program,” explained Ben Jerry Gonzales, one of the study’s lead authors. “It takes control of a circuit the brain already uses for natural actions and pushes behavior toward persistent repetition.” As Neuroscience News notes, this hijacking idea is therefore the heart of the discovery.
The findings reach beyond cocaine, since the same kind of circuit imbalance may drive repetitive behaviors in Tourette syndrome, Parkinson’s disease and obsessive compulsive disorder. Different parts of the striatum control different movements, from limbs to head turning. For example, a similar push and pull gone wrong could explain many compulsive rituals.
The STEREO system itself is a breakthrough. It is a machine learning tool that classifies natural actions straight from raw video. However, old methods relied on slow manual scoring by humans or tracked only single actions. Meanwhile, STEREO watched whole behavioral repertoires shift over days. It is the same spirit of machine intelligence seen in a biological computer built from living brain cells, where AI meets real neurons.
There is hope in the push and pull. Because stimulating the brake pathway instantly restored flexible behavior, scientists now have a clear target. Future treatments might rebalance these opposing circuits. The work also gives researchers a powerful way to test new drugs aimed at restoring behavioral freedom, much like brain chip research and brain computer interfaces are opening new doors between minds and machines.
One caution matters. This was a study in mice, not people. The circuits are similar across mammals, but human addiction is more complex. Still, how cocaine hijacks brain circuit pathways in mice is now visible, and that is where every cure begins.
The MES Times Take. This study is a quiet masterpiece. It shows that addiction is not about weak will, but about how cocaine hijacks brain circuit pathways and turns a strong brain system hostage. The same circuits that let a mouse groom and explore are the ones the drug enslaves. That is sad, but it is also hopeful. But scientists can take a stolen system back. The brake is still there, waiting for a gentle press.
Understanding the loop is the first step out of it. Once we see a loop clearly, we can break it.
