ERP COMPONENTS IN CATEGORY MATCHING TASKS

The current experiment attempts to investigate (1) the effect of seman tic information on the ERP correlate of visual short-term memory (VMP) and (2) the utilizing of the ERP as an objective investigative tool f or the clinical observation of the existence of category-specific brai n systems. Event-related potentials (ERPs) were recorded from 61 locat ions on the scalp of 39 healthy adults in a category (either animals o r fruits/vegetables) match/non-match S1-S2 paradigm. The ERPs revealed a substantially smaller amplitude for the category matching than for non-matching pictures at the posterior brain regions, with greater act ivation of temporo-occipital brain regions changing from the right hem isphere at first to the left hemisphere later, as demonstrated by the current source density (CSD) maps. The ERPs elicited by the category o f animal were larger than the vegetable category, similarly, the anima l-animal matching condition elicited larger ERPs than did the vegetabl e-vegetable matching condition. In addition, the topographic distribut ion of the vegetable-elicited ERPs revealed additional involvement of the right frontal cortex which was absent in the topographic distribut ion of the animal-elicited ERPs. The spatial pattern of the VMP posses ses features specific to semantic processing, and the ERPs differentia te the animal category from the vegetable category, suggesting an obje ctive on-line method to investigate the category-specific information processing among brain-damaged patients. (C) 1998 Elsevier Science Ire land Ltd. All rights reserved.