Misfiring Brain Signals in Schizophrenia Distort View of Reality

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Christopher Pack, Ph.D., expert on schizophrenia research
Christopher Pack, Ph.D.

Recent research led by Christopher Pack, Ph.D., of McGill University, supported in part by his 2008 NARSAD Young Investigator Grant, may help to explain why people with schizophrenia misperceive the world. The new findings, published April 2nd in the Journal of Neuroscience, furthers understanding of what causes people with schizophrenia to interpret hallucinations—seen or heard—as real.

Dr. Pack and team studied a particular mechanism in the brain called the corollary discharge system. Corollary discharges are signals that aid in the integration of sensory and motor signals and make it possible for us to monitor and recognize our own actions.  

“A corollary discharge is a copy of a nervous system message that is sent to other parts of the brain, in order to make us aware that we are doing something,” explained Dr. Pack. “For example, if we want to move our arm, the motor area of the brain sends a signal to the muscles to produce a movement. A copy of this command, which is the corollary discharge, is sent to other regions of the brain, to inform them of the impending movement. If you were moving your arm, and you didn’t have the corollary discharge signal, you might assume that someone else was moving your arm. Similarly, if you generated a thought, and you had an impaired corollary discharge, then you might assume that someone else placed the thought in your mind. Corollary discharges ensure that different areas of the brain are communicating with each other, so that we are aware that we are moving our own arm, talking or thinking our own thoughts.”

In the study, patients with schizophrenia and healthy controls were asked to perform a visual task while looking at a computer screen. The researchers found that compared to controls, patients with schizophrenia made larger errors in localizing visual stimuli. The researchers conclude that the patients have a “noisy” corollary discharge—the extra noise interferes with proper functioning of the signal.

Because the circuits that control eye movements are well understood, Dr. Pack is “optimistic that we can work backward from the behavioral data to the biological basis of the corollary discharge effects.”

Learn more about this research.

Read the paper abstract.

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Article comments

Yes this is very interesting research. We remember our son at age six describing once hearing a voice (s) in his head that he did not recognize as his own; the voice was not pleasant as it accused him of being a bad person-at that time he was stressed in school by bullies his own age. The bullying began in school when he was four, and critical phase of his cognitive development. The principal /teacher who was not sympathetic and also believed bullying was part of life and one should get use to it etc. only aggravated his situation (we removed him from that school, but we now believe the damage had been done, and remained wired into his self-perception only to reemerge when stressed and he felt unapproved or could not meet his expectation). Furthermore our son was left isolated from other pupils who avoided associating with him fearing to be next in line. This voice was own self-perception of the reason he was being targeted or avoided (although we tried in vain to explain he was not the cause), and it developed into irrational thought that prevailed and re- emerged in his late teens when he had his first apparent full blown psychosis in which he thought he was going to be killed etc.Perhaps early traumatic or stressful experiences in childhood effect the proper development of corollary discharge circuits such that when the a person reaches their adolescents or early twenties with additional hormonal, biological /chemical changes of puberty the improper corollary circuit becomes more potent, acute and firmly wired making it nearly impossible for the person to redress their perception of themselves and perception of stressful events or even information.

"...why people with schizophrenia misperceive the world." As a person with schizophrenia, I must say this language is very stigmatizing language. While it is interesting to investigate differences in somatosensory messaging, saying that we "misperceive the world" or "distort reality" is discriminatory language. I'm here in reality as much as you are and some of the differences in how I see the world allow me to see more of reality than someone who would adopt such a cold and constricted worldview.

Hello. How the family can help somebody who has this illness?

David, as much as you think what you are seeing and hearing is "Reality," it is not actuality. It may seem very real to you, but it isn't actually there.

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