Scientists Pinpoint Brain Mechanisms Behind Auditory Hallucinations

The new research reveals why people with conditions like schizophrenia hear voices the rest of us can't

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Traditionally, mental disorders have been categorized under psychological conditions as opposed to neurological ones since they don’t typically involve any visible, physical brain damage. For the same reason, most neuroscience research about mental disorders only investigates changes in a patient’s brain structure and connectivity.

This arrangement means people with certain mental disorders involving auditory hallucinations, like the voices people with schizophrenia can hear but no one else can, have long puzzled scientists. However, new research took a different approach to finding an answer.

Previous Research

To explain why people with schizophrenia and other disorders experience auditory hallucinations, scientists theorized it’s because their brains struggle to distinguish between their inner thought processes and external voices. Yet, how or where, precisely, this misconnect occurs remained unknown.

However, Xing Tian — an associate professor of Neural and Cognitive Sciences at NYU Shanghai and a Global Network Associate Professor for the Center for Neural Science at NYU — has long been fascinated by auditory hallucinations, and his research introduces a possible answer.

Tian followed the research for years until he and his team published a series of works in 2020, 2022, and 2023, revealing a possible neurological explanation behind audio hallucinations in the brain.

Based on their combined research, the team theorized that dysfunctions in two brain signals — a “broken” corollary discharge (CD) and a “noisy” efference copy (EC) - generate audio hallucinations.

Whenever we think about or execute a movement, including speaking, our brain generates corollary discharge (CD) and efference copy (EC) signals. The CD signal is supposed to help us distinguish between external events and our personal actions by dampening our sensory reactions to self-generated actions. Meanwhile, a healthy EC narrows things down by increasing sensory responses related to the specific action being performed.