Table_1_Developmental Trajectories of Letter and Speech Sound Integration During Reading Acquisition.docx

Reading acquisition in alphabetic languages starts with learning the associations between speech sounds and letters. This learning process is related to crucial developmental changes of brain regions that serve visual, auditory, multisensory integration, and higher cognitive processes. Here, we studied the development of audiovisual processing and integration of letter-speech sound pairs with an audiovisual target detection functional MRI paradigm. Using a longitudinal approach, we tested children with varying reading outcomes before the start of reading acquisition (T1, 6.5 yo), in first grade (T2, 7.5 yo), and in second grade (T3, 8.5 yo). Early audiovisual integration effects were characterized by higher activation for incongruent than congruent letter-speech sound pairs in the inferior frontal gyrus and ventral occipitotemporal cortex. Audiovisual processing in the left superior temporal gyrus significantly increased from the prereading (T1) to early reading stages (T2, T3). Region of interest analyses revealed that activation in left superior temporal gyrus (STG), inferior frontal gyrus and ventral occipitotemporal cortex increased in children with typical reading fluency skills, while poor readers did not show the same development in these regions. The incongruency effect bilaterally in parts of the STG and insular cortex at T1 was significantly associated with reading fluency skills at T3. These findings provide new insights into the development of the brain circuitry involved in audiovisual processing of letters, the building blocks of words, and reveal early markers of audiovisual integration that may be predictive of reading outcomes.

在字母语言的阅读习得过程中，首要任务是学习语音声音与字母之间的关联。此学习过程与大脑区域的关键发育变化密切相关，这些区域服务于视觉、听觉、多感官整合以及高级认知过程。本研究采用纵向研究方法，对阅读习得前（T1，6.5岁）、一年级（T2，7.5岁）和二年级（T3，8.5岁）不同阅读成果的儿童进行了音频视觉处理与字母-语音声音对整合的研究。通过音频视觉目标检测功能性磁共振成像范式，我们揭示了早期音频视觉整合效应的特征，即在颞下回和腹侧枕颞叶皮层中，不一致的字母-语音声音对激活程度高于一致的字母-语音声音对。从阅读前（T1）到早期阅读阶段（T2、T3），左侧颞上回的音频视觉处理显著增强。兴趣区域分析显示，在具有典型阅读流畅技能的儿童中，左侧颞上回（STG）、颞下回和腹侧枕颞叶皮层的激活程度有所增加，而阅读能力较差的儿童在这些区域并未展现出相同的发展。在T1时，STG和岛叶皮层部分的双侧不一致效应与T3时的阅读流畅技能显著相关。这些发现为字母音频视觉处理的脑回路发展提供了新的见解，字母是构成词汇的基本元素，并揭示了早期音频视觉整合的标记，这些标记可能预示阅读成果。