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Gamma activity in schizophrenia: evidence of impaired network binding?

Authors
Journal
Clinical Neurophysiology
1388-2457
Publisher
Elsevier
Publication Date
Volume
111
Issue
8
Identifiers
DOI: 10.1016/s1388-2457(00)00347-3
Keywords
  • Gamma
  • Schizophrenia
  • Binding
  • Eeg
  • Erp

Abstract

Abstract Objectives: Gamma (‘40 Hz’) rhythms may play a role in the integration of sensory processing activity. Impaired temporal integration may be a key feature of the associated disturbances in schizophrenia. This is the first study to examine the time course of Gamma activity induced in response to stimuli in this disorder. Methods: Gamma activity induced in response to task-relevant and irrelevant auditory oddball stimuli was examined in 35 medicated schizophrenics and 35 age- and gender-matched normal controls. We employed a moving Welch window with short time FFT to examine the time course of Gamma amplitude. The amplitude spectrum for each time point was de-trended to eliminate any contribution of broad spectrum activity (EEG or EMG) to Gamma amplitude. Results: For targets, schizophrenics showed a significant decrease in post-stimulus Gamma response amplitude in left hemisphere and frontal sites and an increase in right hemisphere and parieto-occipital sites ( P<0.0009). The abnormalities correlated with PANSS general symptom scores. In the non-targets (at a different latency), schizophrenics showed a widespread Gamma decrease ( P<0.0005). Conclusions: The Gamma findings in non-targets may reflect an abnormality in appropriately processing irrelevant stimuli. This could result in defective processing of the context (integration) of relevant target information.

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