F. Ostrosky et al., SEMANTIC PRIMING IN AN OBJECT DECISION TASK IN NORMALS AND ALZHEIMERS-DISEASE - AN ELECTROPHYSIOLOGICAL STUDY, Brain and cognition, 35(3), 1997, pp. 399-403
Semantic memory deterioration is a major symptom observed in dementia
of the Alzheimer's type (DAT). However, the nature of this deficit rem
ains uncertain, some researchers postulate difficulty in accessing and
retrieving semantic information while others point to a degraded stor
ing. In this study, we used the event-related potential, specifically
the component N400, to assess semantic functions. Ten DAT patients and
10 controls were visually presented with 120 prime-targets pairs, 50%
of them belonging to the same category and the other 50% mismatching
the prime. Statistical analysis revealed significant differences just
for the incongruent targets while the amplitude of the congruent ones
was similar for both groups. The lack of this component in DAT patient
s appears to indicate that there is a lack of efficient access and def
icient associative links within the semantic network and therefore see
ms to indicate a breakdown in the structure and organization of semant
ic memory.