Purcell Jeremy J, Jiang Xiong, Eden Guinevere F
Center for the Study of Learning, Department of Pediatrics, United States.
Department of Neuroscience, Georgetown University Medical Center, United States.
Neuroimage. 2017 Feb 15;147:554-567. doi: 10.1016/j.neuroimage.2016.12.054. Epub 2016 Dec 20.
A central question in the study of the neural basis of written language is whether reading and spelling utilize shared orthographic representations. While recent studies employing fMRI to test this question report that the left inferior frontal gyrus (IFG) and ventral occipitotemporal cortex (vOTC) are active during both spelling and reading in the same subjects (Purcell et al., 2011a; Rapp and Lipka, 2011), the spatial resolution of fMRI limits the interpretation of these findings. Specifically, it is unknown if the neurons which encode orthography for reading are also involved in spelling of the same words. Here we address this question by employing an event-related functional magnetic resonance imaging-adaptation (fMRI-A) paradigm designed to examine shared orthographic representations across spelling and reading. First, we identified areas that independently showed adaptation to reading, and adaptation to spelling. Then we identified spatial convergence for these two separate maps via a conjunction analysis. Consistent with previous studies (Purcell et al., 2011a; Rapp and Lipka, 2011), this analysis revealed the left dorsal IFG, vOTC and supplementary motor area. To further validate these observations, we then interrogated these regions using an across-task adaptation technique, and found adaptation across reading and spelling in the left dorsal IFG (BA 44/9). Our final analysis focused specifically on the Visual Word Form Area (VWFA) in the vOTC, whose variability in location among subjects requires the use of subject-specific identification mechanisms (Glezer and Riesenhuber, 2013). Using a functional localizer for reading, we defined the VWFA in each subject, and found adaptation effects for both within the spelling and reading conditions, respectively, as well as across spelling and reading. Because none of these effects were observed during a phonological/semantic control condition, we conclude that the left dorsal IFG and VWFA are involved in accessing the same orthography-specific representations for spelling and reading.
书面语言神经基础研究中的一个核心问题是，阅读和拼写是否利用共享的正字法表征。虽然最近采用功能磁共振成像（fMRI）来测试这个问题的研究报告称，在同一受试者的拼写和阅读过程中，左下额回（IFG）和枕颞腹侧皮质（vOTC）均处于激活状态（珀塞尔等人，2011年a；拉普和利普卡，2011年），但fMRI的空间分辨率限制了对这些研究结果的解读。具体而言，编码阅读正字法的神经元是否也参与相同单词的拼写尚不清楚。在此，我们通过采用一种事件相关功能磁共振成像适应（fMRI-A）范式来解决这个问题，该范式旨在检查拼写和阅读过程中的共享正字法表征。首先，我们确定了独立显示出对阅读适应和对拼写适应的区域。然后，我们通过联合分析确定了这两个独立图谱的空间重叠区域。与先前的研究（珀塞尔等人，2011年a；拉普和利普卡，2011年）一致，该分析揭示了左背侧IFG、vOTC和辅助运动区。为了进一步验证这些观察结果，我们随后使用跨任务适应技术对这些区域进行了研究，并在左背侧IFG（BA 44/9）中发现了阅读和拼写之间的适应现象。我们的最终分析特别关注vOTC中的视觉词形区（VWFA），其在受试者之间的位置变异性需要使用特定于受试者的识别机制（格莱泽和里森胡伯，2013年）。我们使用阅读功能定位器在每个受试者中定义了VWFA，并分别在拼写和阅读条件下以及拼写和阅读之间发现了适应效应。由于在语音/语义对照条件下未观察到这些效应，我们得出结论，左背侧IFG和VWFA参与了获取拼写和阅读相同的正字法特定表征。
