In this month’s Journal of Neuroscience, researchers at Duke University have been able to diagram the circuits in the brain that govern how we hear conversations and music around us. It is these same circuits that can go awry in conditions like schizophrenia when the sufferer hears voices that come from inside. Dr. Richard Mooney, the senior author and a professor of neurobiology at Duke states, “Normally, motor regions would warn auditory regions that they are making a command to speak, so be prepared for a sound. But in psychosis, you can no longer distinguish between the activity in your motor system and somebody else, and you think the sounds coming from within your own brain are external.”
The study found that numerous areas within the brain provide inputs into the auditory cortex. One section known as M2 or the secondary motor cortex was discovered to not only induce motor signals but also anticipate them. By stimulating M2 the brain could be given a false signal, an auditory hallucination.
Much more research is needed but this finding may lead to advances in treatment of mood disorders and in particular, schizophrenia, which according to the World Health Organization affects about 7 per 1,000 in the adult population, 24 million worldwide.