Clinical EEG and Neuroscience, 37(3):271-272, 2006; Psychophysiology, 43:S55, 2006.
Brain responses to novel sounds in depression: an ERP study
Chris J. Kroppmann a, Craig E. Tenke a,c, Jürgen Kayser a,c, James P. Sedoruk a, Carley B. Griggs 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 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
Although reduced P3 amplitude has frequently been reported for clinically-depressed individuals, little is known how depression affects subcomponents of the late positive complex. ERPs (30-channel; nose reference) were recorded from 18 depressed, unmedicated outpatients and 21 healthy adults (all right-handed, 8 men each) during a novelty oddball task (Fabiani & Friedman, 1995). Eight 50-trial blocks consisted of two 300-ms tones (350 Hz nontargets, p=.76; 500 Hz targets, p=.12) and novel sounds (e.g., dog bark, human cough: 100-400 ms, p=.12) presented in pseudorandom order at 1000 ms ISI. Participants responded as quickly as possible to target tones only. Response hand was counterbalanced across blocks. Both groups performed well (hits vs. false alarms: controls 99.5% vs. 1.5%, patients 98.5% vs. 2.6%), yielding comparable ERP components: N1, P2/N2 and early P3 (325 ms peak latency; 220-365 ms integrated time window amplitude) and late P3 (490 ms; 400-650 ms). Early P3 was most prominent for novel stimuli (novelty P3) and had a more frontal topography than late P3, which showed a parietal topography for targets consistent with classic P3b. Although both positive potentials were reduced in depressed patients, the reduction attained statistical significance only for early P3. Moreover, analysis of simple effects confirmed that the group reduction was present only for novel stimuli. Data are compatible with the hypothesis that clinical depression is associated with a reduced frontocentral response to novel stimuli, likely reflecting a deficit in orienting and alerting.
Keywords: ERP, depression, novelty oddball paradigm
