Poster C43, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
The oscillatory mechanisms supporting syntactic binding in healthy aging
Katrien Segaert1,2, Charlotte Poulisse1, Linda Wheeldon3, Ali Mazaheri1,2;1School of Psychology, University of Birmingham, 2Centre for Human Brain Health, University of Birmingham, 3University of Agder, Kristiansand, Norway
Older adults frequently display differential patterns of brain activity compared to young adults when performing the same task. These age-related changes occur alongside widespread neuroanatomical decline. The differential functional activity patterns in older adults are commonly interpreted as being compensatory in nature (e.g., Wingfield & Grossman, 2006; Cabeza et al., 2002). However, most language studies on healthy ageing have not directly examined whether there is a relationship between the changes in neural activity patterns and behavioral performance levels. In the current study, we investigated the relationship between functional neural activation as measured using EEG and behavioural performance during a syntactic binding task. We used a two-word phrase task to minimize contributions of semantics and working memory (Segaert, Mazaheri, Hagoort, 2018). 41 healthy older adults (26 women, mean age: 69, SD: 3.37, 15 men, mean age: 69, SD: 5) listened to two-word phrases that differentially load on morpho-syntactic integration: correct syntactic binding (morpho-syntactically correct; e.g. “I dotch”); incorrect syntactic binding (morpho-syntactic agreement violation; e.g. “they dotches”) and no syntactic binding (minimizing morpho-syntactic binding; e.g. “dotches spuff”). Syntactic comprehension performance, assessed in a syntactic judgement task for the correct and incorrect syntactic binding conditions, was characterized by high inter-individual variability, with accuracy ranging from 58-100%. Syntactic processing, assessed as the difference in oscillatory activity between the correct- and no binding condition, was associated with a smaller theta (4-7Hz) power increase and a larger decrease in both alpha (8-12Hz) and beta (15-20Hz) power in the correct-, relative to the no binding condition (cluster-based permutation tests, Maris & Oostenveld, 2007). There were no ERP differences between the syntactic binding and no binding condition. Similar to the behavioural syntactic performance levels, there was large individual variability in the oscillatory signatures for syntactic processing. However, we found no evidence for a relationship between behavioural comprehension performance and the neural signatures of syntactic processing (also not when accounting for variability in age, gender, processing speed and working memory in the regression models, as motivated by Poulisse, Wheeldon and Segaert, 2019). In conclusion, the neural signatures of syntactic processing in older adults at the group-level are qualitatively different from young adults, who show a differential alpha and beta power increase, instead of a decrease, in the same task (Segaert et al., 2018). In the absence of evidence for a relationship between the neural signatures for syntactic processing and behavioural performance, our findings do not support the predictions of compensatory models of language and aging.
Themes: Syntax, Perception: Auditory
Method: Electrophysiology (MEG/EEG/ECOG)