The scalp distributions of N400 have shown regional and hemispheric differences based on the stimuli, modality and paradigm used for the studies (Curran et al., 1993). It is generally found that the auditory N400 is distributed over the scalp more evenly compared to the visual N400, which shows more of a centroparietal and right hemisphere predominance (Domalski et al., 1991; Franklin et al., 2007; Hill et al., 2002; Kutas and Hillyard, 1982; Kutas and Van Petten, 1988). The word stimuli used in the current study are in the visual modality, and our CSD map (figure 5) reveals a centroparietal and right hemisphere predominant source for the control group only. In contrast, for the primed condition the posterior source is largely central and the sink shifts to the left in the alcoholic group, while the controls have a strong source that is predominantly towards the right hemisphere. The deficits perhaps involve hemispherically asymmetric processes.
