Department of Psychology, University of Jyväskylä, Jyväskylä, Finland; Jyväskylä Centre for Interdisciplinary Brain Research, University of Jyväskylä, Jyväskylä, Finland.
Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands; NatMEG, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Neuroimage. 2020 Oct 15;220:117058. doi: 10.1016/j.neuroimage.2020.117058. Epub 2020 Jun 17.
Learning to associate written letters with speech sounds is crucial for the initial phase of acquiring reading skills. 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. In the present study, we trained 30 Finnish participants (mean age: 24.33 years, SD: 3.50 years) to associate novel foreign letters with familiar Finnish speech sounds on two consecutive days (first day ~ 50 min; second day ~ 25 min), while neural activity was measured using magnetoencephalography (MEG). Two sets of audiovisual stimuli were used for the training in which the grapheme-phoneme association in one set (Learnable) could be learned based on the different learning cues provided, but not in the other set (Control). The learning progress was tracked at a trial-by-trial basis and used to segment different learning stages for the MEG source analysis. The learning-related changes were examined by comparing the brain responses to Learnable and Control uni/multi-sensory stimuli, as well as the brain responses to learning cues at different learning stages over the two days. We found dynamic changes in brain responses related to multi-sensory processing when grapheme-phoneme associations were learned. Further, changes were observed in the brain responses to the novel letters during the learning process. We also found that some of these learning effects were observed only after memory consolidation the following day. Overall, the learning process modulated the activity in a large network of brain regions, including the superior temporal cortex and the dorsal (parietal) pathway. Most interestingly, middle- and inferior-temporal regions were engaged during multi-sensory memory encoding after the cross-modal relationship was extracted from the learning cues. Our findings highlight the brain dynamics and plasticity related to the learning of letter-speech sound associations and provide a more refined model of grapheme-phoneme learning in reading acquisition.
学习将书面字母与语音声音相关联对于获得阅读技能的初始阶段至关重要。然而，对于支持字母-语音声音学习的皮质重组，特别是在学习字形-音素关联时的大脑动态，我们知之甚少。在本研究中，我们训练了 30 名芬兰参与者（平均年龄：24.33 岁，标准差：3.50 岁）在两天内连续关联新的外国字母和熟悉的芬兰语音（第一天约 50 分钟；第二天约 25 分钟），同时使用脑磁图（MEG）测量神经活动。两组视听刺激用于培训，其中一组（可学习）的字形-音素关联可以根据提供的不同学习线索进行学习，但另一组（控制）不能。在逐试的基础上跟踪学习进度，并用于对 MEG 源分析进行不同学习阶段的分段。通过比较可学习和控制的 uni/multi-sensory 刺激的大脑反应，以及两天内不同学习阶段的学习线索的大脑反应，检查与学习相关的变化。我们发现，当字形-音素关联被学习时，与多感官处理相关的大脑反应会发生动态变化。此外，在学习过程中，对新字母的大脑反应也发生了变化。我们还发现，其中一些学习效果仅在第二天记忆巩固后才观察到。总体而言，学习过程调节了包括颞上皮质和背侧（顶叶）通路在内的大脑区域的大网络的活动。最有趣的是，在从中提取学习线索的跨模态关系后，中间和下颞叶区域参与了多感官记忆编码。我们的研究结果强调了与字母-语音声音关联学习相关的大脑动态和可塑性，并为阅读获得中的字形-音素学习提供了更精细的模型。
