Localization of Phonological and Semantic Contributions to Reading

Abstract

Reading involves the rapid extraction of sound and meaning from print through a cooperative division of labor between phonological and lexical-semantic processes. Whereas lesion studies of patients with stereotyped acquired reading deficits contributed to the notion of a dissociation between phonological and lexical-semantic reading, the neuroanatomical basis for effects of lexicality (word vs pseudoword), orthographic regularity (regular vs irregular spelling-sound correspondences), and concreteness (concrete vs abstract meaning)on reading is underspecified, particularly outside the context of strong behavioral dissociations. Support vector regression lesionsymptom mapping (LSM) of 73 left hemisphere stroke survivors (male and female human subjects) not preselected for stereotyped dissociations revealed the differential contributions of specific cortical regions to reading pseudowords (ventral precentral gyrus), regular words (planum temporale, supramarginal gyrus, ventral precentral and postcentral gyrus, and insula), and concrete words (pars orbitalis and pars triangularis). Consistent with the primary systems view of reading being parasitic on language-general circuitry, our multivariate LSM analyses revealed that phonological decoding depends on perisylvian areas subserving sound-motor integration and that semantic effects on reading depend on frontal cortex subserving control over concrete semantic representations that aid phonological access from print. As the first study to localize the differential cortical contributions to reading pseudowords, regular words, and concrete words in stroke survivors with variable reading abilities, our results provide important information on the neurobiological basis of reading and highlight the insights attainable through multivariate, process-based approaches to alexia. Whereas fMRI evidence for neuroanatomical dissociations between phonological and lexical-semantic reading is abundant, evidence from modern lesion studies establishing the differential contributions of specific brain regions to specific reading processes is lacking. Our application of multivariate lesion-symptom mapping revealed that effects of lexicality, orthographic regularity, and concreteness on reading differentially depend on areas subserving auditory-motor integration and semantic control. Phonological decoding of print relies on a dorsal perisylvian network supporting auditory and articulatory representations, with unfamiliar words relying especially on articulatory mapping. In tandem with this dorsal decoding system, anterior inferior frontal gyrus may coordinate control over concrete semantic representations that support mapping of print to sound, which is a novel potential mechanism for semantic influences on reading.

Voxel and surface based whole brain analysis shows reading skill associated grey matter abnormalities in dyslexia

“…This is compatible with the suggestion that DD might be a disconnection syndrome, with poor neural communication between key brain areas involved in reading and, therefore, vitally contributing to this disorder 54 , 60 . Moreover, evidence from lesion studies suggests that damage to the left insula underpins acquired dyslexia 61 . Whereas previous studies reporting left insular structural anomalies in DD are scarce, taken together, these findings suggest that the left insula plays a role in reading, and its structural and functional anomalies in DD should be confirmed and explored further in future studies.…”

Neural Effects of Gender and Age Interact in Reading

“…Because modulation of this area was not specifically hypothesized, we can only speculate as to the significance of interactive effects of age and gender on function in this area. Indeed, the mOFC is not generally considered to be part of the canonical reading network in healthy participants (Fiez and Petersen, 1998; Turkeltaub et al, 2002; Jobard et al, 2003; Binder et al, 2005; Graves et al, 2010; Cattinelli et al, 2013; Taylor et al, 2013; Murphy et al, 2019), nor is it typically implicated in the few brain lesion-deficit group studies to date that have investigated the critical neural systems for reading (Ripamonti et al, 2014; Boukrina et al, 2015; Dickens et al, 2019). It is for these reasons that we have taken a cautious approach to interpreting the mOFC findings.…”

Rethinking causality and data complexity in brain lesion-behaviour inference and its implications for lesion-behaviour modelling

“…It has been postulated that MLBM, which accounts for the mutual dependence of voxels, is the solution to the limitations of mass-univariate VLBM, including the lesionanatomical dependence (Mah et al, 2014;Xu, Jha, & Nachev , 2018). Large parts of the lesion behaviour mapping community adapted this view and repeated the claim that MLBM resolves these limitations of VLBM (e.g., Adolphs, 2016;Carter et al, 2017;Toba et al, 2017;DeMarco & Turkeltaub, 2018;Thye et al, 2018;Xu et al, 2018;Zhao et al, 2018;Dickens et al, 2019;Gläscher, Adolphs, & Tranel, 2019;Howard, Smith, Coslett, Buxbaum, & Krakauer, 2019;Valero-Cabré, Toba, Hilgetag, & Rushmore , 2019;Wong, Jax, Smith, & Buxbaum , 2019). However, empirical findings do not fully support this view.…”