Effective connectivity of visual word recognition and homophone orthographic errors.

Joan Guàrdia-Olmos,Esteve Gudayol-Ferré,Andrés A González-Garrido,Maribel Peró-Cebollero,Daniel Zarabozo-Hurtado

doi:10.3389/fpsyg.2015.00640

Abstract

The study of orthographic errors in a transparent language like Spanish is an important topic in relation to writing acquisition. The development of neuroimaging techniques, particularly functional magnetic resonance imaging (fMRI), has enabled the study of such relationships between brain areas. The main objective of the present study was to explore the patterns of effective connectivity by processing pseudohomophone orthographic errors among subjects with high and low spelling skills. Two groups of 12 Mexican subjects each, matched by age, were formed based on their results in a series of ad hoc spelling-related out-scanner tests: a high spelling skills (HSSs) group and a low spelling skills (LSSs) group. During the f MRI session, two experimental tasks were applied (spelling recognition task and visuoperceptual recognition task). Regions of Interest and their signal values were obtained for both tasks. Based on these values, structural equation models (SEMs) were obtained for each group of spelling competence (HSS and LSS) and task through maximum likelihood estimation, and the model with the best fit was chosen in each case. Likewise, dynamic causal models (DCMs) were estimated for all the conditions across tasks and groups. The HSS group’s SEM results suggest that, in the spelling recognition task, the right middle temporal gyrus, and, to a lesser extent, the left parahippocampal gyrus receive most of the significant effects, whereas the DCM results in the visuoperceptual recognition task show less complex effects, but still congruent with the previous results, with an important role in several areas. In general, these results are consistent with the major findings in partial studies about linguistic activities but they are the first analyses of statistical effective brain connectivity in transparent languages.

Highlights

Reading is a cognitive process that requires visually identifying written elements and their respective phonological association to form meaning
The high spelling skills (HSSs) group was faster than the low spelling skills (LSSs) group in both blocks of the spelling recognition tasks but, in the visuoperceptual recognition task, the HSS group was slower in block C than the LSS group, and the opposite effect in block D
We studied the possible differences in detecting homophone orthographic errors in the neurobiological substrate by using two approaches: analyzing the effective connectivity model estimated through structural equation models (SEMs) and dynamic causal models (DCMs)

Summary

Introduction

Reading is a cognitive process that requires visually identifying written elements and their respective phonological association to form meaning. From an anatomical-functional perspective, the development of the skills needed to process the information of the orthographic structure, phonology and meaning of words, involves activating the participation of several brain regions, mainly cortical, forming what some authors have called a specialized system for reading (Berninger and Richards, 2002). Activations have been reported in the left hemisphere’s fusiform gyrus when faced with the presentation of words in tasks demanding relatively simple manipulation or processing, such as visual priming (Devlin et al, 2006; Glezer et al, 2009), lexical decision (Cohen et al, 2002; Dehaene et al, 2002), or structure-based word decision (Binder et al, 2006; Kronbichler et al, 2008) This region has been called visual word form area or VWFA (Cohen et al, 2000)

Objectives

Methods

Results

Conclusion