Clinical EEG and Neuroscience, 37(3):264, 2006

Clinical EEG and Neuroscience, 37(3):264, 2006; Psychophysiology, 43:S51, 2006.

ERP generator patterns in schizophrenia during tonal and phonetic oddball tasks: effects of response hand and silent count

JÃ¼rgen Kayser^a,c, Craig E. Tenke^a,c, Carley B. Griggs^a, Nathan A. Gates^a, Chris J. Kroppmann^a, Roberto B. Gil^b,c, Gerard E. Bruder^a,c

^a Department of Biopsychology, New York State Psychiatric Institute, New York, New York, USA
^b Department of Clinical Psychobiology, New York State Psychiatric Institute, New York, New York, USA
^c Department of Psychiatry, Columbia University College of Physicians & Surgeons, New York, New York, USA

Abstract

P3 amplitude in schizophrenia has been reported to be more reduced over left than right hemiscalp during auditory oddball tasks, which has been interpreted as left-lateralized dysfunction. However, the contributions of methodological factors (stimulus properties, response mode, recording reference), which affect event-related surface potential (ERP) topographies, remain unclear. We recorded 31-channel ERPs from 20 schizophrenia patients and 20 age- and gender-matched healthy adults (all right-handed) during tonal and phonetic oddball tasks, varying response mode (left press, right press, silent count) also within subjects. Patients performed adequately but were slower. ERP generator patterns were summarized by temporal PCA (unrestricted Varimax) from reference-free current source density (CSD; spherical spline Laplacians) waveforms used to sharpen scalp topographies. CSD factors were unambiguously related to known ERP components and highly comparable between groups. Both groups showed asymmetric frontolateral and parietotemporal N2 sinks and asymmetric centroparietal P3 sources for targets (tonal R>L, phonetic L>R), but patients had reduced frontocentral N2 sinks and reduced midparietal P3 sources. In both groups, left or right press produced opposite, region-specific asymmetries originating from central sites, modulating the N2/P3 complex, and a larger parietal P3 source compared to silent count. Data suggest overall reduced neural generators in schizophrenia during auditory oddball tasks, with both groups showing comparable topographic effects of task and response mode.

Keywords: ERP, schizophrenia, response mode, oddball paradigm, hemispheric differences, principal components analysis (PCA), current source density (CSD)