Development of Brain Mechanisms for Processing Orthographic and Phonologic Representations

Abstract

Developmental differences in the neurocognitive networks for lexical processing were examined in 15 adults and 15 children (9- to 12-year-olds) using functional magnetic resonance imaging (fMRI). The lexical tasks involved spelling and rhyming judgments in either the visual or auditory modality. These lexical tasks were compared with nonlinguistic control tasks involving judgments of line patterns or tone sequences. The first main finding was that adults showed greater activation than children during the cross-modal lexical tasks in a region proposed to be involved in mapping between orthographic and phonologic representations. The visual rhyming task, which required conversion from orthography to phonology, produced greater activation for adults in the angular gyrus. The auditory spelling task, which required the conversion from phonology to orthography, also produced greater activation for adults in the angular gyrus. The greater activation for adults suggests they may have a more elaborated posterior heteromodal system for mapping between representational systems. The second main finding was that adults showed greater activation than children during the intra-modal lexical tasks in the angular gyrus. The visual spelling and auditory rhyming did not require conversion between orthography and phonology for correct performance but the adults showed greater activation in a system implicated for this mapping. The greater activation for adults suggests that they have more interactive convergence between representational systems during lexical processing.

Differential activation of frontal and parietal regions during visual word recognition: An optical topography study

“…Even though we cannot fully exclude the possibility of syllabic representation to drive IPG, we suggest -in line with Binder et al (1999Binder et al ( , 2003 -that the critical difference between words and PWs is the semantic representation exclusive to words, a difference which dominates the differential IPG activation for lexicality. This conclusion receives support from lesion studies of the IPG (see Price, 2000 for an overview), and is in line with the concept proposed by BOLD-contrast findings in studies on dyslexia (Booth et al, 2004;Horwitz et al, 1998;Pugh et al, 2000).…”

“…Pugh et al (2000) provided evidence that dyslexia can be conceived as a disorder of relating print to sound and vice versa, which corresponds to a disruption of the projections between the IPG, and occipital as well as temporal cortical areas (Booth et al, 2004;Horwitz et al, 1998; but see Kronbichler et al, 2006).…”

Phonological development in relation to native language and literacy: Variations on a theme in six alphabetic orthographies

“…Nevertheless, phonological representations may also be directly impacted by learning to read in a manner independent of these newly acquired links to orthography. It remains an empirical question as to which explanation is most likely but emerging fMRI evidence from adults and older children offers support for age-related increases in the recruitment of orthographic processing in rhyming tasks even when, as in the present study, these tasks are delivered exclusively in the auditory modality (Booth et al, 2004). Among adults, Pattamadilok et al (2011) found two ERP components associated with orthographic activation in auditory rhyme judgement: the first occurred during phonological segmentation, and the second, during the task decision process.…”

Developmental changes in brain regions involved in phonological and orthographic processing during spoken language processing

“…Previous research conducted by Booth and colleagues (Booth, et al 2003b;Booth, et al 2004;Booth, et al 2001) employed an auditory rhyme decision task, among other tasks, to compare language processing in adults versus children. One of these studies showed that both adults and children activated left inferior frontal gyrus, bilateral superior/middle temporal gyri, and left fusiform gyrus (Booth, et al 2004).…”

“…One of these studies showed that both adults and children activated left inferior frontal gyrus, bilateral superior/middle temporal gyri, and left fusiform gyrus (Booth, et al 2004). This study also reported that adults showed greater activation than children in left inferior frontal gyrus and left superior temporal gyrus, suggesting that adults engage these nodes of the language network to a greater degree than do children for phonological processing involved in rhyme decisions.…”