Is that my thought - or did someone put it there? How neural dysfunction is linked to schizophrenia symptons


A mechanism in the brain that's responsible for monitoring one's action might explain why schizophrenics experience auditory or visual hallucinations, according to researchers at the Montreal Neurological Institute and Hospital.

A brain signal known as corollary discharge happens when a nervous system message is sent to other parts of the brain to alert us that we are doing something, said lead study investigator Christopher Pack, Ph.D.

“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," Pack explained. "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.”

The concept of corollary discharge might explain why, if a schizophrenic generated a thought - but had an impaired corollary discharge response - that person might think someone else placed that thought in their mind, Pack said.

'Noisy' patterns seen in schizophrenics

Pack's study involved having schizophrenic individuals try to make rapid eye movements following a dot on a computer screen. At the same time, they were asked to locate a visual stimuli that appeared on the screen sporadically.

But the schizophrenic patients were less accurate than others when trying to figure out where they were looking.

“It is not that people with schizophrenia have no corollary discharge, or a corollary discharge with delayed or weaker amplitude," Pack said. "Rather, the patients appear primarily to have a noisy corollary discharge signal. This visual test is a very easy thing to do and quite sensitive to individual differences.”

The nature of the impaired corollary discharge signal could also predict patient symptom severity, the researchers hypothesized.

Results of the study are published in the Journal of Neuroscience.

Source: Psych Central