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Poster A87, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall

Changes in brain activity during learning grapheme-phoneme associations: An MEG study

Weiyong Xu1,2, Orsolya Kolozsvari1,2, Jarmo Hämäläinen1,2;1Department of Psychology, University of Jyväskylä, Finland, 2Jyväskylä Centre for Interdisciplinary Brain Research, University of Jyväskylä, Finland

Learning to associate written letters with speech sounds is crucial for the initial phase of reading acquisition. However, little is known about the cortical reorganization for supporting letter-speech sound learning, particularly the brain dynamics during the learning of grapheme-phoneme associations and effects of memory consolidation during sleep. In the present study, we trained 29 Finnish participants (mean age: 24.12 years, SD: 3.44 years) to learn foreign letters and speech sounds on two consecutive days (first day ~ 50 minutes; second day ~ 25 minutes), while neural activity was measured using magnetoencephalography (MEG). Visual stimuli consisted of 12 Georgian letters (ჸ, ჵ, ჹ, უ, დ, ჱ, ც, ჴ, ნ, ფ, ღ, წ). Auditory stimuli consisted of 12 Finnish speech sounds ([a], [ä], [e], [t], [s], [k], [o], [ö], [i], [p], [v], [d]). The audiovisual learning experiment consisted of 12 alternating learning and testing blocks in Day 1 and 6 learning and testing blocks in Day 2. All participants learned 6 audiovisual pairs based on the feedback about the congruency information of the audiovisual stimuli, while another 6 audiovisual pairs were non-learnable due to the lack of congruency information in the feedback. Overall, the participants learned the correct associations within half an hour of training in Day 1 as indicated by their reaction time and accuracy. In Day 2, although the accuracy already reached ceiling level, there was a decrease of reaction time compared to the last block in Day 1 (Day 1 block 12: 1117 ms±436 ms v.s. Day 2 block 1: 825 ms±153 ms ). Event-related fields (ERFs) were obtained by averaging separately audiovisual congruent and incongruent trials before and after learning of letter-speech sound associations. Audiovisual congruency effects (audiovisual incongruent > audiovisual congruent) were observed in the late time window (300-600ms) in left temporal regions after successful learning of the grapheme-phoneme associations in both Day 1 and Day 2. In addition, compared to the brain responses to non-learnable audiovisual stimuli, there was a suppression in the brain responses to the learnable audiovisual congruent stimuli and enhancement in responses to the incongruent stimuli. Our findings indicated the important role of left temporal region in the initial phase of learning letter-speech sound associations, as well as the memory consolidation during sleep for improvement of learning outcome.

Themes: Multisensory or Sensorimotor Integration, Reading
Method: Electrophysiology (MEG/EEG/ECOG)

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