The neural substrates of writing: A functional magnetic resonance imaging study

Abstract

Plate 1. Surface-rendered projections of statistical maps reflecting activation during (1a) generative writing of words versus repetitive drawing of circles; (1b) generative writing of words versus writing letters of the alphabet; (1c) writing letters of the alphabet versus repetitive drawing of circles; (1d) generative writing of words versus generative subvocal naming of words. Display threshold set at T = 4.02 (uncorrected p < .001; extent threshold 50 voxels). Plate 2. Coronal and axial sections showing activation in the posterior inferior temporal lobe (white arrows), superior parietal region (pink arrows), and Exner's area (green arrows) for the contrasts: (2a) generative writing of words versus repetitive drawing of circles; (2b) generative writing of words versus writing letters of the alphabet; (2c) writing letters of the alphabet versus repetitive drawing of circles. Display threshold set at T = 4.02 (uncorrected p < .001; extent threshold 50 voxels). Plate 3. Sagittal sections showing results of region of interest analysis in the left inferior temporo-occipital region for the contrasts: (3a) generative writing of words versus repetitive drawing of circles; (3b) generative writing of words versus writing letters of the alphabet; (3c) writing letters of the alphabet versus repetitive drawing of circles;(3d) written naming versus generative subvocal naming. Functional magnetic resonance imaging was used with 12 adults to examine activation associated with generative writing of words from semantic categories contrasted with writing letters of the alphabet and drawing circles. In addition, the generative writing condition was contrasted with a subvocal generative naming condition.Outcomes & Results: Semantically guided retrieval of orthographic word forms for the generative writing condition revealed activation in the left inferior and dorsolateral prefrontal cortex, as well as the left posterior inferior temporal lobe (BA 37). However, no activation was detected in the left angular gyrus (BA 39). The motor components of writing were associated with activation in left fronto-parietal cortex including the region of the intraparietal sulcus, superior parietal lobule, dorsolateral and medial premotor cortex, and sensorimotor areas for the hand.

Developmental increases in effective connectivity to brain regions involved in phonological processing during tasks with orthographic demands

“…For both modalities, there were modulatory effects involving inferior frontal gyrus, inferior parietal cortex and fusiform gyrus. This is broadly consistent with studies in adults that have reported activation in these regions in a variety of spelling tasks (Beeson et al, 2003;Booth et al, 2002;Katanoda et al, 2001;Menon and Desmond, 2001;Nakamura et al, 2000;Petrides et al, 1995;Sugihara et al, 2006;Sugishita et al, 1996;Tokunaga et al, 1999). None of these studies, however, found activation in superior temporal gyrus, whereas our study revealed reliable activation in and modulatory effects on connections with superior temporal gyrus in both visual and auditory modalities.…”

“…This suggests that brain regions implicated in phonological, and not semantic processing, were recruited for spelling (Poldrack et al, 1999). Our finding, showing the importance of dorsal inferior frontal gyrus in spelling, is consistent with several studies in adults reporting activation in BA 9/44 in spelling tasks (Booth et al, 2002;Katanoda et al, 2001;Nakamura et al, 2000;Tokunaga et al, 1999), although there is one inconsistent study showing activation in ventral inferior frontal gyrus (Beeson et al, 2003). In addition, our results of developmental increases in the modulatory effects into dorsal inferior frontal gyrus is consistent with studies using a similar auditory spelling task that have shown developmental increases in signal intensity in dorsal inferior frontal gyrus (BA 44/9) (Booth et al, 2003b(Booth et al, , 2004.…”

“…None of these studies, however, found activation in superior temporal gyrus, whereas our study revealed reliable activation in and modulatory effects on connections with superior temporal gyrus in both visual and auditory modalities. This could be explained by task differences as most of previous studies used physical writing which may have placed greater emphasis on motor processes (Beeson et al, 2003;Katanoda et al, 2001;Menon and Desmond, 2001;Nakamura et al, 2000;Petrides et al, 1995;Sugihara et al, 2006;Tokunaga et al, 1999). In contrast, our tasks involved spelling judgments to sequentially presented words, so it is more likely that phonological processes were engaged.…”

“…These studies have used a variety of tasks including mentally writing the written word form (Sugishita et al, 1996), converting Japanese Kana words to Kanji characters and then mentally recalling their visual form (Nakamura et al, 2000), spelling judgments independent of whether words are presented in the auditory or visual modality as compared to rhyming judgments (Booth et al, 2002), physical writing of a visually presented word (Nakamura et al, 2000), physical writing of a spoken word (Menon and Desmond, 2001;Petrideset al, 1995;Tokunaga et al, 1999), physical writing of associates of a semantic category (Beeson et al, 2003), and physical writing of a word referring to a visual picture (Katanoda et al, 2001;Sugihara et al, 2006). The most consistent finding across these spelling studies in adults is activation in left inferior parietal cortex, a region that has been implicated in mapping between phonological and orthographic representations (Booth et al, 2002(Booth et al, , 2003a.…”

Combining treatment for written and spoken naming

“…The phonological codes involved in spelling rely on a network of perisylvian cortical regions, including Broca's area, Wernicke's area, the supramarginal gyrus, and insula (Alexander et al, 1992;Fiez, 1997;Omura et al, 2004;Roeltgen et al, 1983). Orthographic knowledge of lexical representations for reading and spelling is thought to engage a critical region within temporo-occipital cortex (BA 37), sometimes referred to as the visual word form area (Beeson et al, 2003b;Cohen & Dehaene, 2004;Nakamura et al, 2002;Rapcsak & Beeson, 2004). Thus under normal circumstances, spelling engages both perisylvian and extrasylvian cortical regions.…”