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Electrophysiological correlates of short-term word learning and consolidation
Poster A22 in Poster Session A, Thursday, October 6, 10:15 am - 12:00 pm EDT, Millennium Hall
Julie Franco1, Marina Laganaro1; 1University of Geneva
Word learning is a skill that is used daily even in adults (Hartshorne & Germine, 2015) for new words in the mother tongue, in a second language or when recovering from anomia following brain damage. Integrating a new word into the mental lexicon is a complex process that involves several steps from short-term recall to full consolidation (Van der Ven et al., 2015). In adulthood, the human brain is capable of acquiring and memorizing new words rapidly via hippocampal systems first and then through neocortical brain networks as a result of consolidation (Davis & Gaskell, 2009). Word learning processes have been studied mainly with word recognition approaches (Kapnoula et al., 2015; Takashima et al., 2017), and to a lesser extent in word production (Cornelissen et al., 2004; Grönholm et al., 2005; Fargier & Laganaro, 2020). However, most studies focused on short term learning while the brain regions while processes leading to consolidation and lexical integration are still poorly explored. In word recognition, recent research tends to show the involvement of different processes during the different learning phases (Bakker et al., 2015; in eye tracking: Weighall et al., 2017), but studies on the production of newly leaned/consolidated words are missing. The aim of the present study is to investigate electrophysiological correlates of word learning at short-term and consolidation (lexical-semantic integration) with word production (rather than recognition) paradigms. 26 participants learned two matched lists of 40 infrequent words in two x 2-days learning periods, with active digital methods. Test sessions were carried out on word production (picture naming) task with EEG recording before and after each learning period, the last test being 72 hours after 1st learning period, allowing to test consolidation for the first list. Here we report analyses on the list of 40 words learned during the first learning period were at short-term learning assessment (day 3, 1-day after learning) and consolidation (day 5, 3-days after learning), where lexical-semantic integration was also assessed with a picture-word interference task. Results showed higher accuracy at day 3 than at day 1 (z = 7168, p <.001, β = 7.38, SE = 0.001), with no further difference at day 5 (z<1). Reaction times were faster at day 3 relative to day 1 (t(941) = -2.41, p <.05) and further decreased at day 5 (t(1829) = -15.11, p <.001). ERP analyses revealed significant differences between day 1 and day 3 on amplitudes and microstates. In particular, different global electrophysiological patterns, indicating different brain processes, appeared on the P2 component (at ~250 ms after picture onset), which has been previously associated with lexical selection. In the comparison between short term (day 3) and consolidation (day 5) further ERP differences appeared only on microstates, with qualitative differences between 250 and 400 ms after picture onset. The results of the present study show that consolidation 72 hours without additional exposure to the newly learnt words involves further electrophysiological changes during word production in the the time period associated to lexical encoding processes.
Topic Areas: Language Production, Meaning: Lexical Semantics