Morpho-syntax and the aging brain: An ERP study of sentence comprehension in older adult Spanish speakers

Date
2013
Authors
Chaire, Alondra
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Abstract

Normal aging comes with increased knowledge, as well as qualitative and quantitative changes in cognitive processes. Previous work with English monolinguals has shown that event-related potential (ERP) measures of sentence comprehension decrease in amplitude (N400), or change in distribution (P600) with age. However, little is known about the electrophysiological correlates of aging with regard to other languages, especially those with richer morpho-syntax than English. In this study, participants read sentences in Spanish, while 2 ERP components related to sentence comprehension were measured: the N400---reflecting meaning-level processes, and the P600---reflecting brain processes sensitive to syntactic information. Sentences included semantic violations, syntactic (gender agreement) violations, or both types of violations. Our aims were to identify the effects of combined semantic and syntactic violations in relation to the effects of single semantic and single syntactic violations on language comprehension in the healthy aging brain. From previous studies in young adults, we predicted that older adults would exhibit larger N400 amplitudes for semantic violations compared to control sentences and gender agreement violations would elicit an increase in late positive amplitude (LPC) compare to control sentences. In addition, double violations were expected to elicit a boosting of the N400 effect over frontal and prefrontal electrodes compared to semantic violations alone, indicating that gender and semantics interact early in processing. As predicted from young adults, we found that semantic violations elicited an N400 and gender agreement violations elicited an LPCa and LPCb. Additionally, we found an unexpected LPC following the N400 due to semantic violations and a LAN preceding the LPC due to gender violations. Finally, based on previous findings in older adults, we found that the N400 effect was trending to reduce with age and no statistic distinction was found between any of the three violations compared to the control at the LPCb window. This suggests that the older adult brain is taxed by reprocessing a sentence after any type of violation in sentence meaning or structure.

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Integrative Biology