The amplitudes of auditory event-related potentials (ERPs) during simple tone discrimination or “oddball” tasks have been found to be reduced in patients having schizophrenia (e.g.,1–11). This includes early ERPs, such as N1, that are related to sensory or attentional processing, and also the later cognitive N2 and P3 potentials. It has been hypothesized that the reductions of N2 and P3 are related to pathophysiology of temporal lobe structures involved in the generation or modulation of these auditory ERPs.3,12 Additional support for this hypothesis has come from findings of greater reduction in N2 or P3 amplitude to tones in schizophrenia over left than right temporal lobe sites,3,12–16 and from evidence that this is related to asymmetric abnormalities of temporal lobe structures.17–19 Some studies have, however, found bilateral, rather than asymmetric, P3 reduction in schizophrenia20,21 and neuroimaging data showing comparable volume reductions of both left and right temporal lobes.1,22 Further complicating the interpretation of these conflicting findings is evidence showing that reduced P3 may be associated with reversed asymmetries in schizophrenia when handedness is considered, with right-handed patients showing greater reductions of
