Psychophysiology, 44:S109, 2007.

Novelty P3 reductions in depression: characterization using CSD-PCA

Craig E. Tenke^a,c, JÃ¼rgen Kayser^a,c, Christopher J. Kroppmann ^a, Nathan A. Gates^a, Jennifer D. Schaller^a, Jonathan W. Stewart^b,c, Gerard E. Bruder^a,c

^a Department of Biopsychology, New York State Psychiatric Institute, New York, New York, USA
^b Depression Evaluation Service, 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

We recently reported that depressed patients (N = 25) had reduced novelty P3 compared to healthy controls (N = 23) using a 31-channel montage. We report here an independent replication and extension (49 patients; 51 controls) using 67 channels. A novelty oddball task (Friedman et al., 1993) included two 300-ms tones (nontargets: 350 Hz, p = .76; targets: 500 Hz, p = .12) and novel sounds (e.g., dog bark, human cough: 100-400 ms, p = .12) in pseudorandom order at 1000 ms ISI using eight 50-trial blocks. Participants responded as quickly as possible to target tones only, with response hand counterbalanced across blocks. Reference-free current source densities (CSDs; spherical spline Laplacian) derived from ERP waveforms were simplified and measured using temporal, covariance-based principal components analysis (PCA), followed by unrestricted Varimax rotation. Extracted factors were consistent with those reported for a standard oddball (Kayser & Tenke, 2006a,b) including: N1 (120 ms loadings peak), P2/N2 (245 ms), early P3 (351 ms), and late P3 (568 ms). Factor 351 efficiently summarized P3b sources (medial parietal maximum for targets), but included a secondary midline frontocentral source for novel and target stimuli. Within factor 245, a midcentral source (Cz maximum) was present for novels but absent for targets, and was significantly reduced in patients. Spatiotemporal PCA confirmed the specificity of this early midcentral source for novels. Results are consistent with a reduced novelty response in clinical depression, involving multiple novelty P3 and P3b generators.

Keywords: Novelty P3, CSD-PCA, Depression