Reduced brain responses to novel sounds in depression: P3 findings in a novelty oddball task

Gerard E. Bruder, Christopher J. Kroppmann, Jürgen Kayser, Jonathan W. Stewart, Patrick J. McGrath, Craig E. Tenke

Department of Psychiatry (GEB, JK, JWS, PJM, CET), College of Physicians and Surgeons of Columbia University, and Division of Cognitive Neuroscience (GEB, CJK, JK, CET) and Depression Evaluation Service (JWS, PJM), New York State Psychiatric Institute, New York, New York, USA

Received 26 December 2007; revised 26 September 2008; accepted 23 October 2008. 

Abstract

There have been conflicting findings as to whether the cognitive P3 brain potential is reduced in depressed patients. Studies have not generally differentiated P3 subcomponents associated with different cognitive operations and neural generators. The novelty P3 component to distracter stimuli was predicted to be reduced in depressed patients. EEG was recorded from 30 scalp electrodes (nose reference) in 20 unmedicated depressed patients and 20 matched healthy controls during a novelty oddball task with three stimuli: infrequent target tones (p=.12), frequent standard tones (p=.76) and nontarget novel stimuli, e.g., animal or environment sounds (p=.12). Novel stimuli evoked a P3 potential with a more frontocentral topography than the parietal-maximum P3b potential to target stimuli. The novelty P3 was markedly reduced in depressed patients compared to controls. Although there was a trend for patients to also have smaller parietal P3b to targets, this group difference was not statistically significant. Nor was there a group difference in the earlier N1 or N2 potentials. The novelty P3 reduction in depressed patients is indicative of a deficit in orienting of attention and evaluation of novel environmental sounds. A distributed neural network, including prefrontal, anterior cingulate and parietal cortex may be involved in the novelty P3 reduction in depression.

Key Words: Depression, ERP, P3, Novelty, Attention