Auditory event-related potentials and alpha oscillations in the psychosis prodrome: Neuronal generator patterns during a novelty oddball task
Jürgen Kayser1,2, Craig E. Tenke1,2, Christopher J. Kroppmann2, Daniel M. Alschuler2, Shiva Fekri2, Shelly Ben-David2, Cheryl M. Corcoran1,2, Gerard E. Bruder1,2
1Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA; 2Division of Cognitive Neuroscience, New York State Psychiatric Institute, New York, NY, USA
Received 12 June 2013; revised 3 December 2013; accepted 6 December 2013; available online 13 December 2013.
Abstract
Prior research suggests that event-related potentials (ERP) obtained during active and passive auditory paradigms, which have demonstrated abnormal neurocognitive function in schizophrenia, may provide helpful tools in predicting transition to psychosis. In addition to ERP measures, reduced modulations of EEG alpha, reflecting top-down control required to inhibit irrelevant information, have revealed attentional deficits in schizophrenia and its prodromal stage. Employing a three-stimulus novelty oddball task, nose-referenced 48-channel ERPs were recorded from 22 clinical high-risk (CHR) patients and 20 healthy controls detecting target tones (12% probability, 500 Hz; button press) among nontargets (76%, 350 Hz) and novel sounds (12%). After current source density (CSD) transformation of EEG epochs (-200 to 1000 ms), event-related spectral perturbations were obtained for each site up to 30 Hz and 800 ms after stimulus onset, and simplified by unrestricted time-frequency (TF) principal components analysis (PCA). Alpha event-related desynchronization (ERD) as measured by TF factor 610-9 (spectral peak latency at 610 ms and 9 Hz; 31.9% variance) was prominent over right posterior regions for targets, and markedly reduced in CHR patients compared to controls, particularly in three patients who later developed psychosis. In contrast, low-frequency event-related synchronization (ERS) distinctly linked to novels (260-1; 16.0%; mid-frontal) and N1 sink across conditions (130-1; 3.4%; centro-temporoparietal) did not differ between groups. Analogous time-domain CSD-ERP measures (temporal PCA), consisting of N1 sink, novelty mismatch negativity (MMN), novelty vertex source, novelty P3, P3b, and frontal response negativity, were robust and closely comparable between groups. Novelty MMN at FCz was, however, absent in the three converters. In agreement with prior findings, alpha ERD and MMN may hold particular promise for predicting transition to psychosis among CHR patients.
Key Words: Event-Related Potentials (ERP); Current Source Density (CSD); Principal Components Analysis (PCA); Novelty Oddball; Mismatch Negativity (MMN); Time-Frequency Analysis; Alpha ERD; Clinical High-Risk (CHR)