Schizophrenia syncs fast: disconnected brain may lie at heart of disorder.
Interconnected brain areas that use split-second timing to interpret new information suffer a communication breakdown in people with schizophrenia, a new study suggests.
The finding hinges on measurements of some brain waves brain waves Neurology Oscillations/sec that correspond to various types of cerebral activity, as measured on an EEG. See Electroencephalogram. that arise from synchronized activity in large clusters of neurons.
In healthy adults listening to two different tones in a sequence, for example, these aligned brain waves occur about one-tenth of a second after a person first recognizes the tones' difference, say neuroscientist Leanne M. Williams of Westmead (Australia) Hospital and her colleagues. The synchronized electrical outbursts appear most prominently in the frontal brain, a region regarded as a key part of a network that interprets novel perceptions against a background of prior knowledge.
In contrast, people diagnosed with their first bout of schizophrenia display a decline in neural synchrony synchrony /syn·chro·ny/ (-krah-ne) the occurrence of two events simultaneously or with a fixed time interval between them.
atrioventricular (AV) synchrony , especially in the frontal brain, in the fraction of a second after discerning a particular tone, Williams' team reports in the March American Journal of Psychiatry The American Journal of Psychiatry (AJP) is the most widely read psychiatric journal in the world. It covers topics on biological psychiatry, treatment innovations, forensic, ethical, economic, and social issues. . Individuals with schizophrenia exhibit unusually low levels of synchronized neural firing to begin with, the researchers note.
If confirmed in further work, these findings raise the likelihood that "a breakdown in the synchrony of distributed neural networks is a marker for the onset of schizophrenia," the researchers conclude.
For their study, the scientists enrolled 40 people receiving outpatient treatment for an initial episode of schizophrenia--a condition often marked by hallucinations Hallucinations Definition
Hallucinations are false or distorted sensory experiences that appear to be real perceptions. These sensory impressions are generated by the mind rather than by any external stimuli, and may be seen, heard, felt, and even , delusions, incoherence incoherence Not understandable; disordered; without logical connection. See Schizophrenia. , and apathy--and 40 individuals with no psychiatric condition. All participants were either teenagers or young adults. In the schizophrenia group, 36 volunteers had been taking a prescribed antipsychotic medication Antipsychotic medication
A drug used to treat psychotic symptoms, such as delusions or hallucinations, in which patients are unable to distinguish fantasy from reality.
Mentioned in: Bipolar Disorder for around 10 months. The other 4 volunteers had received no such drug.
Scalp electrodes recorded gamma waves, which arise when thousands of neurons emit matching electrical signals around 40 times a second. Other scientists have linked gamma activity to basic types of learning and perception (SN: 2/20/99, p.122). Brain wave measurements were taken as participants tried to ignore low-frequency tones played repeatedly through headphones Head-mounted speakers. Headphones have a strap that rests on top of the head, positioning a pair of speakers over both ears. For listening to music or monitoring live performances and audio tracks, both left and right channels are required. . The volunteers were instructed to press a button as fast as possible whenever they heard high-frequency tones that the researchers also played into the headphones.
As in previous studies, schizophrenia patients took substantially longer to respond to high-frequency tones than their healthy peers did. Moreover, their gamma-wave readings reflected a lack of synchrony.
Williams and her colleagues suspect that their new finding reflects the disease process rather than the effects of antipsychotic medication. To make sure, they plan to study brain wave responses of additional medication-free individuals in the early stages of schizophrenia.
The new data "suggest a disintegration of fast [neural] signaling in early perceptual processing" in schizophrenia, writes neuroscientist Karl Friston of University College London “UCL” redirects here. For other uses, see UCL (disambiguation).
University College London, commonly known as UCL, is the oldest multi-faculty constituent college of the University of London, one of the two original founding colleges, and the first British in comments published with the new report. Out-of-sync neurons can disrupt different parts of brain networks that orchestrate perceptual or emotional learning, perhaps contributing to schizophrenia's variety of symptoms, Friston proposes.
Psychiatrist Daniel R. Weinberger of the National Institute of Mental Health The National Institute of Mental Health (NIMH) is part of the federal government of the United States and the largest research organization in the world specializing in mental illness. in Bethesda, Md., takes a cautious approach to the new study. Disorganized dis·or·gan·ize
tr.v. dis·or·gan·ized, dis·or·gan·iz·ing, dis·or·gan·iz·es
To destroy the organization, systematic arrangement, or unity of. activity in critical brain networks may foster schizophrenia, he says, but it's not clear what causes disrupted gamma-wave activity or how a loss of neural synchrony reverberates through the brain.