Auditory-evoked alpha oscillations imply reduced anterior and increased posterior amplitudes in schizophrenia

Most of the work on disturbed oscillatory activity during auditory tasks in schizophrenia has focused on reduced gamma oscillations at fronto-central sites. Recent studies of our group, however, indicate a more general disturbance affecting the spatial distribution of oscillatory brain activity of gamma as well as slow frequencies, such as alpha oscillations.

During a passive auditory listening task, electroencephalography was recorded from healthy controls and patients with schizophrenia. Stimulus-locked alpha activity within the first 250 ms after stimulus onset was analyzed from midline electrodes.

Healthy controls showed the common fronto-central maximum of the early alpha response, while patients with schizophrenia showed lower fronto-central and larger parieto-occipital alpha activity than controls, leading to a more similar amplitude distribution across the midline electrode sites.

The present results indicate malfunctioning long-range inhibition of task-irrelevant cortical areas in schizophrenia, which may disturb functional integration of perception and attention. We emphasize the importance of the whole-brain network theory for the understanding of schizophrenia since it proposes that integrative brain function is based on the coexistence and cooperative action of many interwoven and interacting sub-mechanisms.

Neuropsychiatric illnesses such as schizophrenia are marked by communication and coordination failures between different brain regions and different frequency bands.