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Altered brain waves explain some schizophrenic symptoms

The hallucinations experienced by schizophrenic patients could be due to a fault in the brain waves associated with cognitive functions, suggests research that provides support for dysfunctional circuitry as a core symptom of schizophrenia.

Robert McCarley, from Harvard Medical School in Boston, Massachusetts, USA, and colleagues found that gamma brain waves, which are involved in the interpretation of information about the environment and formation of mental impressions, are emitted at a slower rate than that for mentally healthy individuals.

The study, published in the Proceedings of the National Academy of Sciences, involved 20 people with schizophrenia and 20 people without the disorder, who were asked to perform a cognitive task while their brain waves were recorded using an electroencephalogram (EEG).

Participants were asked to look at two images, each of which contained four “pacman” figures - circles with a quarter section missing. In one of the images, the shapes faced such a way as to suggest a square in the center of the picture.

When asked to press a button if they saw the square or not, the responses of the schizophrenic patients were found to be an average 200 milliseconds slower than those of the controls. People with schizophrenia also made more mistakes than controls.

Moreover, EEG measurements revealed little gamma activity in the brains of the schizophrenic patients when they pressed the button, unlike their healthy counterparts, whose gamma wave activity was maintained throughout the activity.

The least gamma wave activity - which has a frequency of between 30 to 100 Hertz - was observed in those with the worst symptoms of schizophrenia.

“What some of them did show was a response at a lower frequency, outside the gamma band, which may indicate less efficient communication among neurons,” said McCarley.

“If the most efficient communication between assemblies of neurons is at 40 Hertz, and the schizophrenics are using a lower frequency, it’s likely they have defective communications between assemblies and brain regions.”

Posted by bbeard on 11/23 at 10:27 AM in Science / Technology

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