Slide Slam G14
Asynchronous Behavioral and Neurophysiological Changes in Word Production in the Adult Lifespan
Giulia Krethlow1, Tanja Atanasova1, Eric Ménétré1, Marina Laganaro1; 1Université de Genève
While performance in most cognitive domains (episodic memory, working memory, attention and inhibitory control, general processing speed, etc.) start declining in early adulthood (e.g. Salthouse, 2004) language capacities only decline beyond the age of 60-70 years-old (e.g. Salthouse, 2010). Behavioral changes in language tasks between young and older adults are accompanied by changes in neurophysiological brain activity. In referential word production tasks (picture naming), Valente & Laganaro (2015), reported ERP brain activations divergences between young and older adults in a specific time-window, between 150 and 250 ms after the picture onset. This time period is associated with lexical-semantic processes and suggested that word production modifications in aging could be influenced by the age-related changes affecting the semantic system and its processing. However, most neuroimaging studies on aging of language skills compared only extremes of the adulthood (20-30 years-old and older than 70). It is therefore unclear when the observed neurophysiological changes start in the adult lifespan and whether they only arise in older adults. In this study we aimed to investigate the electrophysiological (EEG) and event-related (ERP) patterns underlying word production in a picture naming task across the adult lifespan, i.e. by including intermediate age-groups between young adults and elderly, thus filling the gap between the two extremities of the adult lifespan. High-density EEG was recorded in 95 French native speakers aged 16 to 80 years-old divided into five age-groups named: “adolescents”, “young adults”, “adults”, “young-old adults” and “older adults”. Behavioral results showed that only the “older adults” group (70-80 years-old) displayed slower production latencies relative to the “young adults” group (20-30 years-old). However, significant neurophysiological changes are already observed starting from the age of 40. Microstates analyses showed a specific pattern in all age-groups over 40 years, but not in the two youngest groups. This specific pattern was observed in the time window between 150 and 220 milliseconds after the image onset, likely associated with lexical-semantic processes and its presence progressively increased in the three older adult groups. Source localization in this specific time-window, highlighted with aging a shift from temporo-occipital to more frontal activation and an activation of a more temporo-parietal extended network. The present findings indicate that neurophysiological changes related to word production appear from the age of 40 year-old, i.e. long before behavioral decline. The time window and source localization of such progressive changes are compatible with an enrichment/reorganization of the lexical-semantic network throughout the lifespan. This observation is in line with the hypothesis of the “semanticization of cognition”, which predicts a maintenance or a growth of semantic abilities over the lifespan and a decline in cognitive control resources with age (Spreng & Turner, 2019). This mechanism would allow the maintenance of language skills longer than for other cognitive functions. These results lead to consider that studying language processes using mostly undergraduate young adults (20-30 years-old), may not be representative to study “adulthood”.