Neural Responses of the Anterior Ventral Occipitotemporal Cortex in Developmental Dyslexia: Beyond the Visual Word Form Area

Abstract

PURPOSE. For the past 2 decades, neuroimaging studies in dyslexia have pointed toward a hypoactivation of the ventral occipitotemporal cortex (VOTC), a region that has been closely associated to reading through the extraction of a representation of words which is invariant to position, size, font or case. However, most of the studies are confined to the visual word form area (VWFA), while recent studies have demonstrated a posterior-to-anterior gradient of print specificity along the VOTC. In our study, the whole VOTC, partitioned into three main patches of cortex, is assessed in dyslexic and control adults. METHODS. A total of 30 participants were included in this study (14 developmental dyslexics and 16 age-and education-matched controls). The design consisted of alternately viewed blocks of stimuli from a given class (words, consonant strings, phase-scrambled words, phasescrambled consonant strings, small checkerboards, large checkerboards). The analyzed contrast was print stimuli (words and consonants) versus scrambled stimuli and checkerboards. RESULTS. Corroborating previous findings, our results showed underactivation to print stimuli in the VWFA of dyslexics. Additionally, differences between dyslexics and controls were also found, particularly in an area of the anterior partition of the VOTC, suggesting a relevant role of this area in word processing. CONCLUSIONS. In sum, our study goes beyond the underactivation hypothesis in the VWFA of dyslexics and indicates that a particular area on the anterior fusiform region might be particularly involved in the reading deficits in dyslexia, demonstrating the involvement of multiple areas within VOTC in reading processes.

Is Developmental Dyslexia Due to a Visual and Not a Phonological Impairment?

“…The question of whether the VWFA plays a role in DD has been addressed by some investigators by examining the excitability of the VWFA using mainly fMRI. In several fMRI studies, subjects with dyslexia showed reduced activation in the classic VWFA [233][234][235], and the adjacent anterior regions of the left fusiform gyrus compared to normal readers [236][237][238][239][240][241][242][243][244]. Reduced activation of the word form area that is part of the left ventral occipital cortex is a common finding in subjects with dyslexia [179,180,188,193,194,222,229,232,[245][246][247][248][249][250].…”

Music literacy improves reading skills via bilateral orthographic development

“…There is much evidence to suggest that injury to the left occipitotemporal area can lead to impaired reading ability, including pure alexia 87 , 88 or transient alexia 89 . Consistently, developmental dyslexia (in the absence of brain damage) is instead associated with insufficient or atypical activation of the left occipito-temporal ventral cortex activation for words 88 , 90 – 96 . This atypical or insufficient activity would result in smaller amplitudes of the left occipital/temporal N170 in response to words that symbols 91 , 97 , as compared to controls.…”

Can Prediction Error Explain Predictability Effects on the N1 during Picture-Word Verification?

“…However, phase-shuffled words were employed as an alternative comparison for exploratory analyses, with equal spatial-frequency amplitude and permuted spatial-frequency phase. Similar phase-shuffled word stimuli have shown robust differences to word forms in fMRI investigations of vOT activity (Rauschecker et al, 2012; Rodrigues et al, 2019; White et al, 2019; Yeatman et al, 2013).…”