This study examined the relationship between ERP components elicited by deviant stimuli by disentangling the P300 and Novelty P3 components, using spatiotemporal principal components analysis and a dense electrode array. The three-tone paradigm was used and the pitch attributes of the tones were systematically manipulated so as to map the amplitude of the ERP components on the stimulus context. A comparison was made between the components elicited by events in the three-stimulus, classical oddball, and novelty oddball paradigms. Responses to deviant stimuli consisted of independent and dissociable ERP components in the 400–600-ms time range: A parietal component (P300) that was larger for targets than rare nontargets and was affected by the difficulty of discrimination, a fronto-central component (Novelty P3) that was larger for novel tones and for rare nontargets in the difficult discrimination condition, and an additional anterior negative component responded similarly to all types of deviant stimuli.

We used a novel application of principal components analysis (spatiotemporal PCA) to decompose the event-related brain potentials (ERPs) obtained with a dense electrode array, with the purpose of elucidating the late ERP components elicited by deviant stimuli under “attend” and “ignore” conditions. First, a “spatial” PCA was performed to identify a set of scalp distributions (spatial factors or “virtual electrodes”) that accounted for the spatial variance in the data set. The data were expressed as spatial factor scores or “virtual ERPs” measured at each of the virtual electrodes. These virtual ERPs were submitted to a “temporal” PCA, yielding a set of temporal factors or “virtual epochs.” Statistical analyses of the temporal factor scores found that (1) attended deviant stimuli elicited the P300 and Novelty P3 components, the latter being largest for highly salient nontargets; (2) “ignored” deviants elicited a small Novelty P3, and depending on the primary task, a small P300; and (3) the classical Slow Wave consisted of separate frontal-negative and posterior-positive components.

In this study, we examined the relationship between the novelty P3 and the P300 components of the brain event-related potential (ERP). Fifteen subjects responded manually to the rare stimuli embedded either in a classical auditory oddball series or in a series in which “novel” stimuli were inserted. The electroencephalogram (EEG) was recorded with a dense array of 129 electrodes. The data were analyzed by using spatial Principal Components Analysis (PCA) to identify a set of orthogonal scalp distributions, “virtual electrodes” that account for the spatial variance. The data were then expressed as ERPs measured at each of the virtual electrodes. These ERPs were analyzed using temporal PCA, yielding a set of “virtual epochs.” Most of the temporal variance of the rare events was associated with a virtual electrode with a posterior topography, that is, with a classical P300, which was active during the virtual epoch associated with the P300. The novel stimuli were found to elicit both a classical P300 and a component focused on a virtual electrode with a frontal topography. We propose that the term Novelty P3 should be restricted to this frontal component.

The effects of attention were assessed on novelty P3 amplitude and scalp distribution elicited by environmental sounds in young and elderly volunteers who participated in either actively attended or ignored oddball conditions. For the young, novelty P3 amplitude decreased with time on task during both attend and ignore sequences. Amplitude decrements were greatest at frontal sites during the attend condition, but at all sites during the ignore condition. A reliable amplitude decrement was not observed for the elderly in either the attend or ignore oddball series. The data suggest that attention differentially activates multiple generators that contribute to scalp-recorded novelty P3 activity. The lack of novelty P3 habituation seen in the elderly is consistent with changes in frontal lobe function as age increases.