Scientists say they have identified faulty brain waves that may explain the symptoms of schizophrenia.
Communication between brain cells may be poorer in schizophrenia
Cells in the brain that exchange information about the environment and form mental impressions were less active in people with schizophrenia.
This might explain and help treat the hallucinations and disordered thinking people with schizophrenia experience, says the Harvard Medical School team.
The study appears in Proceedings of the National Academy of Sciences.
Researchers looked at the brain wave patterns of 20 people with schizophrenia and 20 healthy volunteers.
The study participants were asked to look at either of two images containing four 'Pac-man' figures - circles with a quarter missing.
In one image, the four shapes were arranged to optically suggest a square in the centre. The participants were asked to press a button to show if they perceived a square or not.
At the same time, the scientists monitored the participants' brain waves using EEG, which gives a trace of the brain's electrical activity.
Both groups were able to respond to the images within a second, but those with schizophrenia made more errors and took about 200 milliseconds longer to process the image.
When the researchers looked at the brain wave patterns they found the patients with schizophrenia showed no activity in a certain wave band when performing the button-pushing task.
However, the healthy volunteers had visible gamma wave activity, indicating that their brains were processing the visual information to guide their response.
Delta waves below 4 hertz occur during sleep
Alpha waves 8-13 hertz occur at relaxed, quiet times
Beta waves 13-30 hertz occur when we are actively thinking
Gamma waves 30-100 hertz involved in higher mental activity
Lead researcher Dr Robert McCarley said: "There was a pretty dramatic difference. The schizophrenics did not show this gamma-band response at all.
"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 communication between cell assemblies and brain regions."
He said drugs to promote a normal gamma response might be helpful in schizophrenia.
"If you know the neurochemical identity of the neurons and synapses involved in generating gamma activity, you can try to target treatments toward them."
Marjorie Wallace, chief executive of the mental health charity SANE, said: "If this study is replicated, it could throw some light on why people with schizophrenia perceive the world around them differently from others.
"We hope that research like this will bring us nearer to an understanding of the patterns of activity in the brain that are associated with the symptoms of schizophrenia.
"Only in this way will we eventually find better treatments for this destructive condition."
Paul Corry, from the mental health charity Rethink, said: "We welcome any new research or progress into understanding the causes of schizophrenia, but it would need to be checked before it would make a difference to the thousands of people living with severe mental illness in the UK.
"In the meantime, reaching people early with the right care and treatment is the best way of recovering a meaningful and fulfilling life."
Professor Ed Bullmore, Medical Research Council neuroscience board member, said: "It's interesting research but we would need more studies to see in the future whether this could be used as a marker of a genetic cause or a predictor of outcome."