Neuronal generator patterns of olfactory event-related brain potentials in schizophrenia

Jürgen Kayser^1,2, Craig E. Tenke^1,2, Dolores Malaspina³, Christopher J. Kroppmann¹, Jennifer D. Schaller¹, Andrew Deptula¹, Nathan A. Gates¹, Jill M. Harkavy-Friedman², Roberto Gil^2,4, Gerard E. Bruder^1,2

¹Division of Cognitive Neuroscience, New York State Psychiatric Institute, New York, NY, USA; ²Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA; ³Department of Psychiatry, New York University School of Medicine, New York, NY, USA; ⁴Division of Translational Imaging, New York State Psychiatric Institute, New York, NY, USA

Received 25 August 2009; revised 17 October 2009; accepted 13 November 2009; published online 23 Apr 2010.

Abstract

To better characterize neurophysiologic processes underlying olfactory dysfunction in schizophrenia, nose-referenced 30-channel EEG was recorded from 32 patients and 35 healthy adults (18/18 male) during detection of hydrogen sulfide (constant-flow olfactometer, 200 ms unirhinal exposure). ERPs were transformed to reference-free current source density (CSD) waveforms and analyzed by unrestricted Varimax-PCA. Participants indicated when they perceived a high (10 ppm) or low (50% dilution) odor concentration. Patients and controls did not differ in detection of high (23% misses) and low (43%) intensities, and also had similar olfactory ERP waveforms. CSDs showed a greater bilateral frontotemporal N1 sink (305 ms) and mid-parietal P2 source (630 ms) for high than low intensities. N1 sink and P2 source were markedly reduced in patients for high intensity stimuli, providing further neurophysiological evidence of olfactory dysfunction in schizophrenia.

Key Words: Olfaction, Schizophrenia, Event-related potential (ERP), Current source density (CSD), Principal components analysis (PCA), Surface Laplacian