Poster D44, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
Semantic information facilitates memory trace formation for novel morphology: neuromagnetic investigation
Viktória Roxána Balla1, Yury Shtyrov2,3,4, Miika Leminen5, Alina Leminen1;1University of Helsinki, 2Aarhus University, 3Saint Petersburg State University, 4Higher School of Economics, 5HUS Helsinki University Hospital
Learning to recognize morphemic boundaries is crucial for fluent language comprehension and production. Therefore, in languages with a rich morphology, such as Finnish, the question of morphological learning is particularly relevant. A crucial part of consolidating memories is assimilating new information into existing knowledge. Neurocognitive studies propose that morphologically complex words are decomposed to their constituent elements that are stored as separate units in lexical memory. However, neural mechanisms underlying the acquisition and consolidation of novel morphological units remain obscure. To address this question, we presented complex words that incorporated four novel derivational suffixes to 19 right-handed native Finnish-speaking participants. For half of the new suffixes, we provided semantic information through a word-picture association task. Following this short training session, we used magnetoencephalography (MEG) to record the participants’ brain responses to the novel semantically trained and untrained suffixes combined with real stems and pseudo-stems in an auditory passive listening task, a well-known tool for probing long-term memory traces for spoken stimuli. The stems used in this test were not used in the preceding semantic training as such. To assess the online acquisition dynamics, we compared the responses measured early (first 25% of trials, ~5 minutes after the onset of the passive exposure) and late (last 25% trials/~5 minutes) in passive exposure to investigate the online learning of novel suffixes. We investigated neural source activation in time-windows around the main peaks of event-related field (ERF) responses. We found an increased activation in left frontal and temporal regions of interest, that was present throughout the passive exposure, for the semantically trained compared to the untrained suffixes in the 60-80 ms and 120-140 ms time-windows following the suffix onset. This effect reflects more efficient decomposition of suffixes, for which semantic information had been provided through the word-picture association task. This effect of semantic training was highest when the suffixes were combined with real word stems rather than unfamiliar pseudo-stems, in which case decomposition might be less successful. However, in the 220-260 ms time-window, we found a reduction in difference between responses for real and pseudoword stems towards the end of the exposure, which may indicate online acquisition of novel stems even in the absence of semantic reference. Finally, we detected a general response attenuation over time in the earlier time windows that appeared to be greater for trained suffixes, which might indicate predictability, priming or repetition suppression effects that are more prominent for elements with stronger memory traces. Overall, our findings suggest that a short semantic training of novel affixes significantly facilitates morphological decomposition and speeds up suffix memory trace formation in the left fronto-temporal neocortical networks.
Themes: Morphology, Meaning: Lexical Semantics
Method: Electrophysiology (MEG/EEG/ECOG)