Scientists discover link between hallucitions & dopamine

 New York, Feb 17: People with schizophrenia, who experience auditory hallucitions, tend to hear what they expect an exaggerated version of a perceptual distortion that is common among other people without hallucitions. According to the researchers, those with hallucitions and other psychotic symptoms are known to have elevated dopamine — the main area of focus for available treatments for psychosis — but it was unclear how this could lead to hallucitions. The researchers found that elevated dopamine could make some patients rely more on expectations, which could then result in hallucitions. “Our brain uses prior experiences to generate sensory expectations that help fill in the gaps when sounds or images are distorted or unclear,” said Guillermo Horga, Assistant Professor at Columbia University Medical Centre. “In individuals with schizophrenia, this process appears to be altered, leading to extreme perceptual distortions, such as hearing voices that are not there,” Horga added. For the study  researchers designed an experiment that induces an auditory illusion in both healthy participants and participants with schizophrenia. They examined how building up or breaking down sensory expectations can modify the strength of this illusion. They also measured dopamine release before and after administering a drug that stimulates the release of dopamine. Patients with hallucitions tended to perceive sounds in a way that was more similar to what they had been cued to expect, even when sensory expectations were less reliable and illusions weakened in healthy participants, the researcher said. (IANS)