Alcohol-Related ERP Changes Recorded From Different Modalities: A Topographic Analysis Howard L. Cohen, Jun Ji, David B. Chorlian, Henri Begleiter, and Bernice Porjesz Background: There is controversy in the literature regarding the relationship between event-related- potential (ERP) abnormalities in abstinent alcoholics and stimulus-processing modality (i.e., visual versus auditory). The first purpose of this study was to address questions about whether ERP abnormalities observed in alcoholics are modality specific. The second purpose was to employ current source density (CSD) analyses to investigate topographic differences between alcoholics and controls within each modality. Methods: Data were collected from 30 sober male alcoholics and 39 normal males in a typical auditory oddball task and in a visual oddball paradigm with novel stimuli, with an extensive set of 61 scalp electrodes. Visual and quantitative assessment of CSD maps as well as analyses of variances on both raw and normal- ized ERP data were performed. Results: Positive findings were limited to the N1 and P3 components. The visual N1 amplitude was significantly smaller in alcoholics than in controls at the parietal region; no significant group differences in N1 were found in the auditory modality. Alcoholics had widespread reductions in P3 amplitudes in both modalities compared with controls, although in the frontal region this effect was partially due to the influence of age. These P3 reductions in alcoholics were statistically more pronounced in the posterior compared with the anterior regions regardless of modality. Topographically, sources in CSD maps were weaker in alcoholics than in controls; in the frontal and central regions, the weakness was more pronounced in the auditory modality but, in parietal and occipital regions, it was more pronounced in the visual modality. Conclusions: The results suggest that, in abstinent alcoholics, abnormalities in auditory ERPs may be localized to more anterior sources, while abnormalities in visual ERPs may be localized to more posterior sources. ERP topographic features are more sensitive than amplitude measurements in assessing alcoholic- related modality effects. Key Words: Topography, Alcoholics, P3, N1, Modality, CSD. E VENT RELATED POTENTIALS (ERPs) recorded in the oddball paradigm have provided abundant mea- surements that differentiate groups with and without alco- hol dependence (Glenn et al., 1996; Porjesz and Begleiter, 1996). The most robust ERP feature is the lower P3 am- plitude in abstinent alcoholics (Cohen et al., 1995; Emmer- son et al., 1987, Glenn et al., 1994, Pfefferbaum et al., 1987; Porjesz et al., 1980; Porjesz and Begleiter, 1987); decreased N1 amplitude as well as prolonged N2 and P3 latencies are less consistent findings (Glenn et al., 1996; Porjesz and Begleiter, 1987; Romani and Cosi, 1989). The typical odd- ball task given to sober alcoholics requires effortful or controlled processes, because subjects are making a button- press response or mentally counting the number of target stimuli (Pfefferbaum et al., 1991; Porjesz et al., 1980). The target stimulus is usually the oddball which appears ran- domly and less frequently in a series of more frequent and physically different (i.e., high versus low tone or triangle versus square shapes) stimuli in either the auditory or visual modality; in a dual-modality paradigm, it is the at- tended oddball within one modality with respect to the rare stimulus of the other modality (Porjesz and Begleiter, 1983). In precise terms, the target-elicited P3 in such par- adigms is actually the P3b component, and the reduction in its amplitude is a widely observed phenomenon in alcohol- ics (Porjesz and Begleiter, 1996). This observation is fur- ther corroborated by single trial analyses, which take the variability of latency into consideration (Pfefferbaum et al., 1991). In contrast, some investigations of P3b have failed to observe an amplitude deficit in male (Hill et al., 1995,1999; Steinhauer et al., 1987) and female (Hill et al., 1999; Par- sons, 1994; Parsons et al., 1990) alcoholics and in auditory (Hill et al., 1995,1999; Parsons et al., 1990; Steinhauer et From the Department of Psychiatry (HLC, JJ, DBC, HB, BP), State University of New York, Health Science Center at Brooklyn, New York; and the Institute of Mental Health (JJ), Beijing Medical University, Beijing, China. Received for publication January 31, 2001; accepted December 5, 2001. This research was supported by NIH Grants AA05524 and AA02686 (HB, BP). Reprint requests: Dr. Bernice Porjesz, Department of Psychiatry, Box 1203, SUNY, HSCB, 450 Clarkson Avenue, Brooklyn, NY 11203; Fax: 718-270- 4081; E-mail: bp@bp.cns.hscbklyn.edu. Copyright © 2002 by the Research Society on Alcoholism. 0145-6008/02/2603-0303$03.00/0 ALCOHOLISM:CLINICAL AND EXPERIMENTAL RESEARCH Vol. 26, No. 3 March 2002 Alcohol Clin Exp Res, Vol 26, No 3, 2002: pp 303–317 303