An Investigation of Twenty/20 Vision in Reading

Abstract

One functional anatomical model of reading, drawing on human neuropsychological and neuroimaging data, proposes that a region in left ventral occipitotemporal cortex (vOT) becomes, through experience, specialized for written word perception. We tested this hypothesis by presenting numbers in orthographical and digital form with two task demands, phonological and numerical. We observed a main effect of task on left vOT activity but not stimulus type, with increased activity during the phonological task that was also associated with increased activity in the left inferior frontal gyrus, a region implicated in speech production. Region-of-interest analysis confirmed that there was equal activity for orthographical and digital written forms in the left vOT during the phonological task, despite greater visual complexity of the orthographical forms. This evidence is incompatible with a predominantly feedforward model of written word recognition that proposes that the left vOT is a specialized cortical module for word recognition in literate subjects. Rather, the physiological data presented here fits better with interactive computational models of reading that propose that written word recognition emerges from bidirectional interactions between three processes: visual, phonological, and semantic. Further, the present study is in accord with others that indicate that the left vOT is a route through which nonlinguistic stimuli, perhaps high contrast two-dimensional objects in particular, gain access to a predominantly left-lateralized language and semantic system.

Influence of lexical status and orthographic similarity on the multi-voxel response of the visual word form area

“…Such top-down task-related effects have been reported in VWFA (Hellyer et al, 2011; Mano et al, 2013; Wang et al, 2011). However, even if it would turn out that the representation of lexical status in VWFA is task dependent, its observation under the current active task conditions still shows that lexicality is relevant to the internal organization of VWFA.…”

Top‐down and bottom‐up influences on the left ventral occipito‐temporal cortex during visual word recognition: An analysis of effective connectivity

“…We want to emphasize that the present DCM findings therefore do not imply irrelevance of top-down signals for the functioning of the left vOT in general. There is overwhelming evidence that in many cases of letter-string and visual object processing, top-down signaling is crucial for the left vOTs functional response [e.g., Devlin et al, 2006;Hellyer et al, 2011;Kherif et al, 2011;Mano et al, 2012;Reich et al, 2011;Twomey et al, 2011]. Still, the present study shows that bottom-up signaling is of theoretical importance for understanding the function of this area.…”

“…There is overwhelming evidence that in many cases of letter-string and visual object processing, top-down signaling is crucial for the left vOTs functional response [e.g., Devlin et al, 2006;Hellyer et al, 2011;Kherif et al, 2011;Mano et al, 2012;Reich et al, 2011;Twomey et al, 2011]. We observed that bottom-up signaling from the occipital cortex to the left vOT strongly increases for pseudohomophones.…”

Resting-State and Task-Based Functional Brain Connectivity in Developmental Dyslexia

“…Interestingly, McCrory et al (2005) found that dyslexic readers exhibited reduced local brain activation in the occipito-temporal cortex not only for word reading but also for picture naming. This indicates an impairment of a more general function which implies the left occipito-temporal cortex, namely the integration between visual and verbal information (see also Price and Devlin 2003 , 2011 ; Devlin et al 2006 ; Hellyer et al 2011 ; Kherif et al 2011 ). We found support for this hypothesis by showing permanently reduced connectivity between left occipito-temporal areas and the left IFG.…”