Magazine article Clinical Psychiatry News

MRI, PET Map Source of Schizophrenia Symptoms

Magazine article Clinical Psychiatry News

MRI, PET Map Source of Schizophrenia Symptoms

Article excerpt

NEW YORK -- Using functional MRI and PET, it is possible to map the locations in the brain that are active during hallucinations and delusions--the core symptoms of schizophrenia, Dr. David A. Silbersweig said at a schizophrenia conference sponsored by Columbia University and the New York State Psychiatric Institute.

He presented findings from several imaging studies, which showed that hallucinations were associated with specific patterns of activity in sensory association cortices and mesolimbic and subcortical regions. Paranoid delusions were associated with an inappropriate mesolimbic threat response to neural stimuli.

Dr. Silbersweig described a 23-year-old patient with visual and auditory verbal hallucinations who had never taken antipsychotic drugs. The patient was scanned with PET in a dark, quiet room during active hallucinations and while not hallucinating. When compared with healthy controls, the scans during active hallucinations showed clear activity in visual and auditory-linguistic association cortices (Nature 378[6553]:176-79, 1995)

"Brain regions that are active in healthy controls only when they are seeing and hearing things in the external environment were active in this schizophrenic patient in a dark, quite room while he was hallucinating," Dr. Silbersweig said. Even though hallucinations may seem bizarre, subjective, and ephemeral, the patient is experiencing them and is responding logically to what his brain is telling him, he said.

In addition to brain areas that become activated in the absence of external stimuli, it appears that other brain areas have decreased activity. Dr. Silbersweig's imaging studies have found that an area of the prefrontal cortex involved in monitoring and controlling the temporal lobe is less active than it should be. This may be contributing to the production of hallucinations.

One theory of hallucinations suggests that they are a result of internal dialogue perceived to be coming from the outside. …

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