Our integrative neuroscience model of schizophrenia highlights the lack of coordinated neural activity required for effective processing of salient and task-relevant stimuli. The ‘auditory oddball’ task taps the fundamental mechanisms of selecting and responding to salient stimuli, and disturbances on this task are a trait-like marker for schizophrenia. The objective of this study was to use functional magnetic resonance imaging (fMRI) to identify the neural circuits underlying disturbances processing oddball stimuli in firstepisode schizophrenia (FES).
fMRI data were collected from 24 people with FES (within 3 months of service contact) and 24 matched healthy controls while performing an auditory oddball task comprising 15% target (high) tones and 85% standard (low) tones. Data were analyzed in SPM2, with event-related analysis of the supramarginal gyrus, thalamus, and limbic and prefrontal cortical areas.
The FES group showed significantly reduced activity in the thalamus, hippocampus, dorsal lateral prefrontal cortex and supramarginal gyrus, but a pattern of enhancement as well as reduction in medial prefrontal/anterior cingulate activity, compared with controls.
These findings suggest that schizophrenia is associated with impairments in networks for processing salience as well as context from the first episode of this illness. Dysregulation of medial prefrontal areas may reflect an attempt to compensate for a fundamental breakdown in the coordination of these processes.