Abstract
According to cognitive models of reading, words are processed by interacting orthographic (spelling), phonological (sound), and semantic (meaning) information. Despite extensive study of the neural basis of reading in healthy participants, little group data exist on patients with reading deficits from focal brain damage pointing to critical neural systems for reading. Here, we report on one such study. We have performed neuropsychological testing and magnetic resonance imaging on 11 patients with left-hemisphere stroke (<=5 weeks post-stroke). Patients completed tasks assessing cognitive components of reading such as semantics (matching picture or word choices to a target based on meaning), phonology (matching word choices to a target based on rhyming), and orthography (a two-alternative forced choice of the most plausible non-word). They also read aloud pseudowords and words with high or low levels of usage frequency, imageability, and spelling-sound consistency. As predicted by the cognitive model, when averaged across patients, the influence of semantics was most salient for low-frequency, low-consistency words, when phonological decoding is especially difficult. Qualitative subtraction analyses revealed lesion sites specific to phonological processing. These areas were consistent with those shown previously to activate for phonology in healthy participants, including supramarginal, posterior superior temporal, middle temporal, inferior frontal gyri, and underlying white matter. Notable divergence between this analysis and previous functional imaging is the association of lesions in the mid-fusiform gyrus and anterior temporal lobe with phonological reading deficits. This study represents progress toward identifying brain lesion-deficit relationships in the cognitive components of reading. Such correspondences are expected to help not only better understand the neural mechanisms of reading, but may also help tailor reading therapy to individual neurocognitive deficit profiles.
Highlights
Reading is an important skill in contemporary society and its impairment as a result of brain damage represents a significant handicap
The results presented here represent an important step toward filling a gap in current knowledge by qualitatively identifying potential critical neural substrates of the major cognitive components of reading
This model has been useful in interpreting functional magnetic resonance imaging data (Fiez et al, 1999; Binder et al, 2005; Frost et al, 2005; Graves et al, 2010b), and has led to conceptual advances in understanding acquired reading disorders such as those arising from impaired semantic processing (Woollams et al, 2007)
Summary
Reading is an important skill in contemporary society and its impairment as a result of brain damage represents a significant handicap. Despite decades of research into the cognitive and Reading deficits in left stroke neural mechanisms of reading, a basic question of what are the critical neural substrates supporting the cognitive components of reading remains unresolved Our approach to this question is to use a theoretical framework from computational modeling which distinguishes three main components of reading: visual form (orthography), sound (phonology), and meaning (semantics). It conceives of reading as an interactive activation of orthography, phonology, and semantics. This model has been useful in interpreting functional magnetic resonance imaging (fMRI) data (Fiez et al, 1999; Binder et al, 2005; Frost et al, 2005; Graves et al, 2010b), and has led to conceptual advances in understanding acquired reading disorders such as those arising from impaired semantic processing (Woollams et al, 2007)
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