Scientists are pulling back the curtain on a mysterious phenomenon - how hallucinations are produced in the brain.
- A new study focused on mice has found a key neural circuit that may be responsible for psychotic disorders. Researchers at Cold Spring Harbor Laboratory developed a new model of testing after showing mice are just as susceptible to psychosis as humans are. Test subjects, humans and mice alike, reported how confidently they heard a sound played, which was obscured with background noise.
Mice were trained to indicate whether they'd heard a sound, demonstrating their confidence by how long they waited for a reward. The researchers found that similar to humans, mice were more likely to falsely report sounds when sounds played more frequently and when a hallucinogen, ketamine, was administered. By monitoring the rodents' brains, the researchers found elevated dopamine levels preceding hallucinations.
According to senior author, Adam Kepecs, "A neural circuit in the brain balances prior beliefs, and the higher the baseline level of dopamine, the more people rely on prior beliefs. We think that hallucinations occur when this neural circuit gets unbalanced and antipsychotics rebalances", he told Washington University's The Source. While dopamine is known to play a role in psychosis, how the chemical rewires brain circuitry to produce hallucinations remains a mystery.
The new model could allow researchers to probe deeper and identify new treatments for psychotic disorders. "Right now, we're failing people with serious psychiatric conditions because we don't really understand the neurobiology of the disease", Capex explained. "We're not going to make progress in treating psychiatric illnesses until we have a good way to model them in animals."