Noisy Brain Signals

Summary: How the schizophrenic brain misinterprets the world.

Source: The Journal of Neuroscience.

People with schizophrenia usually misinterpret what they see and experience in the world.

New research provides knowledge about the brain mechanisms that might be responsible for this misinterpretation. The study reports that certain mistakes in visual perception in people with schizophrenia are consistent with interference or ‘noise’ in a brain signal known as a corollary discharge. Corollary discharges are observed throughout the animal kingdom, from bugs to fish to humans, and they are thought to be of great importance for keeping check on one’s own actions.

Schizophrenia is a disorder that interferes with the potential to think clearly and to manage emotions. People with schizophrenia usually attribute their own thoughts and actions to external sources, as in the case of auditory hallucinations. Other general symptoms include delusions and disorganized thinking and speech.

The study identifies a corollary discharge dysfunction in schizophrenia, which could assist with diagnosis and treatment of this difficult disorder.

For this study researchers used a test known as perisaccadic localization task, to look into corollary discharge activity. In this test, participants were asked to make quick eye movements to follow a dot on a computer screen. Simultaneously they were also asked to localize visual stimuli that appear for a short time on the screen from time to time. In order to perform this task accurately, participants needed to know where on the screen they were looking – in other words they use corollary discharge signals that emerge out of the brain structures that control the eye muscles.

The study reports that patients with schizophrenia make mistakes in confining visual stimuli compared to controls. These results could be justified by a corollary discharge signal, which also predicts patient symptom severity, suggesting a possible grounds for some of the most common symptoms of schizophrenia.