ERP ASSESSMENT OF SEMANTIC MEMORY IN ALZHEIMERS-DISEASE

This study used the technique of Event-Related Potentials (ERPs), spec ifically the component N400, to evaluate semantic functions in Alzheim er's disease (AD). ERPs of 10 patients with probable AD and 10 asympto matic elderly control subjects were recorded during a semantic categor ization task using pictures as stimuli, 50% of the stimuli were congru ent and the other 50% were incongruent. Significant differences for th e incongruent ERPs, with a diminished N400 component, was observed in the patients group whereas the amplitude of the congruent ERPs was sim ilar in both groups. The characteristics of the N400 in the patients w ith probable AD suggest that there is a lack of efficiency in accessin g information and shows that there are deficient associative connectio ns within the semantic network. (C) 1997 Elsevier Science B.V.