In summary, twin studies consistently show substantial heritability of oddball-P3. Linkage and association studies have identified several genetic loci and candidate genes that may contribute to the variability in both traditional peak amplitude measure and more novel measures based on time-frequency decomposition of evoked and induced brain oscillations. However, the use of oddball P3 as an intermediate phenotype may be somewhat limited by the lack of specificity in its conceptual interpretation in terms of the underlying neural processes and cognitive correlates. Since multiple interpretations of P3 continue to exist focusing on context updating, attention, cortical inhibition, etc., it is difficult to link individual differences in P3 to variability in a specific cognitive process and its neural underpinnings. There is emerging evidence that P3 is composed of multiple overlapping oscillatory components (Rangaswamy et al., 2007), presumably originating from different sources. The location and time courses of neural generators contributing to P3 have been investigated using source reconstructions of scalp-recorded EEG, ERP recordings in patients with focal brain lesions, intracranial depth electrode recordings in humans and primates, fMRI registration during the performance
