Using ERPs during a complex visual oddball task, Houston et al. (2003) computed CSD using the realistic head-shape boundary element method to study laterality effects (frontal asymmetry) of depression and of a family history of alcohol or substance dependence on P3 component in young women, and found decreased P3-related CSD activations in the depressed group, maximally over the right prefrontal region, compared to subjects with no history of depression, suggesting laterality effects during P3 processing. Based on their prior auditory P3 findings of P3 asymmetry in depressed patients (Bruder et al., 1995), Bruder et al. (1998) tested the hypothesis in depressed outpatients and also examined the CSD topography using the nearest neighbor (local Laplacian) method (Hjorth, 1980). P3 asymmetry was observed in control participants and in depressed patients with low anhedonia, but not for patients with high anhedonia scores. Similarly, Laplacian maps corresponding to P3 showed greater radial current flow over right than over left central regions in control participants and in patients with low anhedonia, suggesting that depression (with low anhedonia) may be associated with hemispheric asymmetry during auditory
