title: Impairments in background and event-related alpha-band oscillatory activity in patients with schizophrenia.
abstract: Studies show that patients with schizophrenia exhibit impaired responses to sensory stimuli, especially at the early stages of neural processing. In particular, patients' alpha-band (8-14 Hz) event-related desynchronization (ERD) and visual P1 event-related potential (ERP) component tend to be significantly reduced, with P1 ERP deficits greater for visual stimuli biased towards the magnocellular system. In healthy controls, studies show that pre-stimulus alpha (background alpha) plays a pivotal role in sensory processing and behavior, largely by shaping the neural responses to incoming stimuli. Here, we address whether patients' ERD and P1 deficits stem from impairments in pre-stimulus alpha mechanisms. To address this question we recorded electrophysiological activity in patients with schizophrenia and healthy controls while they engaged in a visual discrimination task with low, medium, and high contrast stimuli. The results revealed a significant decrease in patients' ERDs, which was largely driven by reductions in pre-stimulus alpha. These reductions were most prominent in right-hemispheric areas. We also observed a systematic relationship between pre-stimulus alpha and the P1 component across different contrast levels. However, this relationship was only observed in healthy controls. Taken together, these findings highlight a substantial anomaly in patients' amplitude-based alpha background activity over visual areas. The results provide further support that pre-stimulus alpha activity plays an active role in perception by modulating the neural responses to incoming sensory inputs, a mechanism that seems to be compromised in schizophrenia.
authors.affiliation: Program in Cognitive Neuroscience, Department of Psychology, The City College of the City University of New York, New York, New York, United States of America; Program in Cognitive Neuroscience and Schizophrenia, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, United States of America.
authors.forename: Ilana Y
authors.initials: IY
authors.lastname: Abeles
authors.affiliation: Program in Cognitive Neuroscience, Department of Psychology, The City College of the City University of New York, New York, New York, United States of America; The Zanvyl Krieger Mind Brain Institute, The Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Manuel
authors.initials: M
authors.lastname: Gomez-Ramirez
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D054022:Cerebrum / Q000473:pathology / Q000503:physiopathology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D012559:Schizophrenia / Q000473:pathology / Q000503:physiopathology*