Neural Dynamics in Schizophrenia

Kevin Spencer, Psychiatry, Harvard Medical School,

Gamma oscillations (30-100 Hz) may play an important role in the representation and selection of information in the brain by synchronizing neural activity into transient attractor states. Abnormalities in elements of the neural circuitry underlying gamma oscillations have been reported in schizophrenia, suggesting that the psychotic and cognitive symptoms of this disorder may be related to abnormal neural dynamics, particularly gamma synchronization. Supporting this hypothesis, schizophrenia patientsí hallucination symptoms were associated with reduced sensory-evoked activity but enhanced perception-related activity in the electroencephalogram, consistent with evidence for cortical hyperexcitability. Hallucinations in schizophrenia could result from an increased propensity for a hyperexcited neural network to visit attractor states independently of external influences, such as sensory stimulation or an attentional signal from prefrontal cortex. This proposal is supported by computational models of gamma oscillations that mimic the effects of neural circuit abnormalities found in schizophrenia.