Shared orthographic neuronal representations for spelling and reading

Abstract

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.

The impact of spelling regularity on handwriting production: A coupled fMRI and kinematics study

“…It has been shown that competition between representations in the linguistic system (Zhuang, Tyler, Randall, Stamatakis, & Marslen-Wilson, 2014) and increased duration of certain stages of processing (Coull, Charras, Donadieu, Droit-Volet, & Vidal, 2015) lead to increases of the BOLD signal in the regions where the relevant information is processed. In the left FuG, the increase is probably related to the competition between representations and/or lengthened processing in orthographic long-term memory (Purcell, Jiang, & Eden, 2017;Purcell et al, 2011;Rapp & Dufor, 2011;Rapp et al, 2016). The left IFG showed the most reliable pattern of differences between regular and irregular words in the 3 models tested.…”

Recovery of orthographic processing after stroke: A longitudinal fMRI study

“…Its role in orthographic specific processing has been reported in both the neuroimaging and lesion literature. In the neuroimaging literature, the left IFJ has been found to be functionally active in both reading and spelling, along with the left FG (Purcell, Jiang, & Eden, 2017; Purcell, Napoliello, et al, 2011; Rapp & Lipka, 2011). The lesion literature includes reports that damage to this region is associated with deficits in orthographic lexical processing in spelling (Hillis, Chang, Breese, & Heidler, 2004; Rapp et al, 2015).…”

Neural Correlates of Orthographic Access in Mandarin Chinese Writing: An fMRI Study of the Word-Frequency Effect

“…Some studies have used spelling judgment tasks in which participants were required to press buttons to report the correct spelling of words or letters presented visually or auditorily. Several brain regions have been found to subserve the retrieval of orthographic codes, including the left posterior inferior frontal gyrus (Rapp and Lipka, 2011 ; Purcell et al, 2017 ), the fusiform gyrus (Kronbichler et al, 2004 ; Philipose et al, 2007 ; Rapp and Dufor, 2011 ), the supplementary motor area (SMA) (Purcell et al, 2017 ), and the superior parietal lobule/inferior parietal sulcus (Purcell et al, 2011 ). However, such spelling judgment tasks are inherently different from actual writing.…”