Poster A38, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB
The dynamics of lexico-semantic access in the aging brain
Rocío López Zunini1, Martijn Baart1,2, Arthur Samuel1,3,4, Blair Armstrong1,5;1BCBL, Basque Center on Cognition, Brain and Language, 2Tilburg University, 3IKERBASQUE, Basque Foundation for Science, 4Stony Brook University, 5University of Toronto, Scarborough
We investigated how aging modulates lexico-semantic processing in the visual (written), auditory (spoken), and audiovisual (written+spoken) modalities. Participants were 20 young and 21 older adults who performed a delayed lexical decision task (LDT), in which word and pseudoword responses were made 1750 ms after stimulus onset. An electroencephalogram was recorded as participants completed blocks of visual, auditory, and audiovisual stimuli. Neural correlates of lexico-semantic access were investigated with Event-Related Potentials (ERPs) at the single trial level. Our results revealed that young and older adults identified words and pseudowords with similar accuracy. However, there were substantial differences in brain dynamics across the groups that included: 1) a right-lateralized distribution of lexico-semantic access as indexed by the N400 effect (i.e., larger negativities for pseudowords than words) in older adults, whereas young adults exhibited a widespread effect in the left, middle and right electrodes, 2) longer lasting N400 effects in the visual and audiovisual modalities in older adults relative to young adults, and 3) a larger effect in the audiovisual modality in older adults than in young adults. These results suggest that the evidence used as a basis for making lexical decisions changes with age, potentially reflecting increased reliance on semantic fields of broader breadths in the right hemisphere in older adults.
Topic Area: Meaning: Lexical Semantics