Younger Jessica W, Booth James R
Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, TX, United States.
Department of Psychology and Human Development, Vanderbilt University, Nashville, TN, United States.
Front Hum Neurosci. 2018 Mar 23;12:109. doi: 10.3389/fnhum.2018.00109. eCollection 2018.
Neuroimaging work from developmental and reading intervention research has suggested a cause of reading failure may be lack of engagement of parietotemporal cortex during initial acquisition of grapheme-phoneme (letter-sound) mappings. Parietotemporal activation increases following grapheme-phoneme learning and successful reading intervention. Further, stimulation of parietotemporal cortex improves reading skill in lower ability adults. However, it is unclear whether these improvements following stimulation are due to enhanced grapheme-phoneme mapping abilities. To test this hypothesis, we used transcranial direct current stimulation (tDCS) to manipulate parietotemporal function in adult readers as they learned a novel artificial orthography with new grapheme-phoneme mappings. Participants received real or sham stimulation to the left inferior parietal lobe (L IPL) for 20 min before training. They received explicit training over the course of 3 days on 10 novel words each day. Learning of the artificial orthography was assessed at a pre-training baseline session, the end of each of the three training sessions, an immediate post-training session and a delayed post-training session about 4 weeks after training. Stimulation interacted with baseline reading skill to affect learning of trained words and transfer to untrained words. Lower skill readers showed better acquisition, whereas higher skill readers showed worse acquisition, when training was paired with real stimulation, as compared to readers who received sham stimulation. However, readers of all skill levels showed better maintenance of trained material following parietotemporal stimulation, indicating a differential effect of stimulation on initial learning and consolidation. Overall, these results indicate that parietotemporal stimulation can enhance learning of new grapheme-phoneme relationships in readers with lower reading skill. Yet, while parietotemporal function is critical to new learning, its role in continued reading improvement likely changes as readers progress in skill.
来自发育和阅读干预研究的神经影像学研究表明，阅读障碍的一个原因可能是在最初习得字素-音素（字母-发音）映射时，顶颞叶皮质未被激活。随着字素-音素学习和成功的阅读干预，顶颞叶激活增加。此外，刺激顶颞叶皮质可提高低能力成年人的阅读技能。然而，尚不清楚刺激后的这些改善是否归因于字素-音素映射能力的增强。为了验证这一假设，我们使用经颅直流电刺激（tDCS）来操纵成年读者的顶颞叶功能，让他们学习一种具有新字素-音素映射的新型人工拼字法。参与者在训练前接受了对左下顶叶（L IPL）20分钟的真刺激或假刺激。他们在3天的时间里每天接受10个新单词的明确训练。在训练前的基线阶段、三个训练阶段的每个阶段结束时、训练后的即时阶段以及训练后约4周的延迟阶段对人工拼字法的学习进行评估。刺激与基线阅读技能相互作用，影响对训练单词的学习以及向未训练单词的迁移。与接受假刺激的读者相比，当训练与真刺激配对时，低技能读者表现出更好的习得效果，而高技能读者表现出更差的习得效果。然而，所有技能水平的读者在顶颞叶刺激后对训练材料的保持都更好，这表明刺激对初始学习和巩固有不同的影响。总体而言，这些结果表明，顶颞叶刺激可以增强低阅读技能读者对新字素-音素关系的学习。然而，虽然顶颞叶功能对新学习至关重要，但随着读者技能的进步，其在持续阅读改善中的作用可能会发生变化。
