| Schizophrenia has long been considered a disconnection syndrome. Though a growing body of literature has identified network disruptions in the structural integrity of the brain in schizophrenia patients, much less is known about the organization of brain activity as it unfolds in real time. The present work was designed to examine the dynamic properties of brain activation during the resting state in a large sample of schizophrenia patients and healthy comparison participants using electroencephalography (EEG). Three studies examined three different properties of the resting-state EEG: (1) network measures of inter-electrode synchrony; (2) temporal patterns within the fluctuating time series of inter-electrode synchrony; and (3) the duration and topography of quasi-stable brain states that occur spontaneously during rest. It was expected that schizophrenia patients would exhibit properties of the EEG consistent with a more "random" organization of brain activity compared to healthy controls. Furthermore, it was expected that the degree of disruption would be associated with measures of symptom severity. The present studies yielded mixed results, although there was some indication that the dynamic properties of resting-state brain activity were more "random" in schizophrenia patients than in healthy comparison participants. Furthermore, increased randomness in the properties of the EEG tended to be associated with more severe perceptual disturbances, lower cognitive function, and a higher degree of schizotypy in schizophrenia patients and healthy controls. Such findings lend credence to the disconnection hypothesis of schizophrenia and suggest that abnormalities in resting-state brain dynamics can capture variation in the severity of symptoms associated with the psychiatric illness. |
