Mismatch negativity in recent-onset and chronic schizophrenia: a current source density analysis.

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Psychiatry

Background:

• Mismatch negativity (MMN) is an auditory event-related potential reflecting pre-attentive change detection.
• Reduced MMN amplitude is a known biomarker in schizophrenia.
• Previous studies show MMN abnormalities in schizophrenia, but detailed network and latency analyses are needed.

Purpose of the Study:

• To compare duration-deviant MMN in recent-onset and chronic schizophrenia patients versus controls.
• To investigate the neural sources and network dynamics of MMN using cortically-constrained LORETA.
• To explore correlations between MMN measures, clinical symptoms, and functional outcomes.

Main Methods:

• Comparison of duration-deviant MMN in 16 recent-onset and 19 chronic schizophrenia patients with age/sex-matched controls.
• Cortically-constrained LORETA analysis of individual MRI data to model MMN current source density.
• Region of Interest (ROI) analysis for early and late MMN phases, and latency measurements.

Main Results:

• Both schizophrenia groups showed reduced frontal MMN with decreased hemispheric asymmetry.
• MMN amplitude reductions were observed in temporal and parietal regions, with delayed onset latency in secondary auditory cortex.
• MMN generation involved a temporal, parietal, and frontal network, right-dominant in controls but not patients.

Conclusions:

• Schizophrenia is associated with widespread MMN amplitude reductions and altered network lateralization.
• Delayed MMN onset latency suggests impaired auditory cortex processing or connectivity as a core deficit.
• MMN abnormalities correlate with clinical severity and functional impairment in schizophrenia.