title: Parallel interhemispheric processing in aging and alcoholism: relation to corpus callosum size.
abstract: We tested parallel processing of visual information using the redundant targets effect (RTE) in 12 alcoholics and 13 matched controls. The paradigm was a simple reaction time (RT) task with targets presented in the same (uncrossed), opposite (crossed), or both (redundant) visual-fields. In older alcoholics (>50 years) the RT gain invoked by redundant targets did not exceed probability measures, suggesting compromised interhemispheric processing of parallel information in this subgroup compared with controls or younger alcoholics. The difference between crossed and uncrossed reaction times (CUD), an index of interhemispheric transfer time (ITT), was greater in older than younger subjects. Moreover, the CUD was negatively correlated with the corpus callosum (CC) total area and body in controls, supporting the concept of a structure-function relationship of interhemispheric transfer. This relationship was not found in alcoholics, although the midsagittal area of the CC, genu, and body but not intracranial volume (ICV), was significantly smaller in alcoholics than controls. These results suggest that chronic alcohol abuse together with advancing age exert subtle disruption on parallel interhemispheric processing reliant on callosal connections.
authors.affiliation: Department of Psychiatry and Behavioral Sciences (MC 5723), Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305-5723, USA.
authors.forename: T
authors.initials: T
authors.lastname: Schulte
authors.forename: A
authors.initials: A
authors.lastname: Pfefferbaum
authors.forename: E V
authors.initials: EV
authors.lastname: Sullivan
mesh_terms: D000328:Adult; D000375:Aging / Q000473:pathology*; D000437:Alcoholism / Q000473:pathology* / Q000503:physiopathology*; D001288:Attention; D016022:Case-Control Studies; D003337:Corpus Callosum / Q000473:pathology*; D004292:Dominance, Cerebral; D005260:Female; D006801:Humans; D007360:Intelligence; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011597:Psychomotor Performance; D011930:Reaction Time; D014796:Visual Perception / Q000502:physiology*; D014888:Wechsler Scales