Scientists find glitch in schizophrenia sufferers’ brains

<body leftmargin="0" bgcolor="#000060" text="#FFFFFF" link="#FFFF00" vlink="#FF9900"> <b> <p class="MsoNormal">Scientists find glitch in schizophrenia sufferers’ brains</p> </b> <p class="MsoNormal"><font face="Arial" size="1">Posted Nov. 8, 2004<br>  World Science staff<br> and Proceedings of the National Academy of Sciences</font><b> <font size="2" face="Arial"><br> <br> Scientists say they have gained new insight into what’s wrong with the brains of schizophrenia – and in the process, possibly learned more about how the brain creates consciousness in all of us. </font></b> </p> <b> <p class="MsoBodyText"><font face="Arial" size="2">How the brain generates consciousness is perhaps the ultimate mystery of science. Part of the puzzle is what scientists call the “binding problem”: how the brain unifies stimuli into a coherent whole. In other words, if we see a green car speeding to the left, how do we identify this as one unified event, given that our perceptions for “green,” “car,” “motion” and “left” are created in different parts of the brain?</font></p> <p class="MsoNormal"><font face="Arial" size="2">Growing evidence suggests the solution to the binding problem lies in the tendency of large groups of brain cells to act synchronously. Huge groups of cells from different brain regions can begin to fire electrical signals together in waves, in a way that suggests they are exchanging key information to collect their perceptions into a unified and sensible whole. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">The theory is still unproven. But scientists now report that this oscillatory signalling is impaired in schizophrenia sufferers, particularly when they perform a task related to the “binding problem.”<o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">The researchers, from the Veterans Affairs Boston Healthcare System and Harvard Medical School, studied the brain waves of normal and schizophrenic patients as they looked at simple images. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">Schizophrenics, unlike healthy participants, showed no brain waves of the type that healthy brain cells are widely believed to use to exchange information. These oscillations, called “gamma-band oscillations,” are waves that take place with a frequency of about 30 to 100 waves per second.<o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">"The schizophrenics did not show this gamma-band response at all. There was a pretty dramatic difference," said Robert W. McCarley, chairman of the Harvard psychiatry department and the lead researcher in the study. The findings were published in the Nov. 8 issue of the research journal Proceedings of the National Academy of Sciences. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">The team recorded the brain waves of 20 schizophrenic and 20 normal patients as they looked at either of two images containing "Pac-man" figures. In one image, the four shapes were arranged to optically suggest a square in the center. The participants had to press a button to show if they perceived the square or not. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">Both groups were able to respond within a second, but those with schizophrenia made more errors and took about about one-fifth of a second longer on average to process the images. The slower reaction times were linked to slower brain wave activity, the researchers said.  <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">This “may indicate less efficient communication among neurons," said McCarley. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">There are other types of brain waves than the “gamma-band oscillations” that are often considered important for the binding problem. The types of brain waves are divided by their frequency, or how quickly the waves follow each other. The schizophrenics had brain wave activities at slower levels than the healthy participants, McCarley said. And among the schizophrenics, the ones with the strongest slow waves were those with the worst schizophrenia symptoms. <o:p> </o:p> </font></p> <p class="MsoNormal"><font face="Arial" size="2">Schizophrenia affects about one percent of the population and is the most common psychotic illness. Contrary to popular notion, it does not involve a "split personality"; that is a rare and separate condition. The disease does involve delusions, in which patients may think others are plotting against them; hallucinations, where they hear voices or see figures that aren't real; and disorganized thinking and behavior, where they may have trouble conversing or focusing on a task. <o:p> </o:p> </font></p> <font face="Arial" size="2">Antipsychotic medications help many patients control symptoms, but often have unwanted side effects. McCarley said drugs that promote a normal gamma response among neurons would likely help the condition.</font> </b> <p> <b> <font size="2" face="Arial"><a href="http://groups.yahoo.com/group/world-science">http://groups.yahoo.com/group/world-science</a></font> </b> </p> </body>