Top-down modulation of ventral occipito-temporal responses during visual word recognition

Abstract

Although interactivity is considered a fundamental principle of cognitive (and computational) models of reading, it has received far less attention in neural models of reading that instead focus on serial stages of feed-forward processing from visual input to orthographic processing to accessing the corresponding phonological and semantic information. In particular, the left ventral occipito-temporal (vOT) cortex is proposed to be the first stage where visual word recognition occurs prior to accessing nonvisual information such as semantics and phonology. We used functional magnetic resonance imaging (fMRI) to investigate whether there is evidence that activation in vOT is influenced top-down by the interaction of visual and nonvisual properties of the stimuli during visual word recognition tasks. Participants performed two different types of lexical decision tasks that focused on either visual or nonvisual properties of the word or word-like stimuli. The design allowed us to investigate how vOT activation during visual word recognition was influenced by a task change to the same stimuli and by a stimulus change during the same task. We found both stimulus- and task-driven modulation of vOT activation that can only be explained by top-down processing of nonvisual aspects of the task and stimuli. Our results are consistent with the hypothesis that vOT acts as an interface linking visual form with nonvisual processing in both bottom up and top down directions. Such interactive processing at the neural level is in agreement with cognitive and computational models of reading but challenges some of the assumptions made by current neuro-anatomical models of reading.

Functional Dynamics of Dorsal and Ventral Reading Networks in Bilinguals

“…The implementation of additional phonological and semantic processes supporting reading in transparent and opaque orthographies (e.g., Paulesu et al 2000) depends upon initial stages of visual word recognition thought to be carried out by left vOT (Twomey et al 2011). Therefore, we sought to use whole-brain functional connectivity methods to identify brain regions that were recruited in concert with left vOT during word reading as a function of L2 orthographic depth.…”

“…Given previous evidence suggesting that orthographic depth has an impact on the semantic and phonological computations needed for successful reading (e.g., Das et al, 2011) and that the left vOT is a critical hub for visual word recognition (e.g., Twomey et al 2011), we considered that the left vOT may be a critical region to observe differential functional dynamics with ventral and dorsal reading networks. Thus, in line with hypothesis V and in contrast to the connectivity analysis circumscribed to the functional coupling within each of the reading networks, we conducted whole-brain connectivity analysis using the left vOT as a seed to examine the profile of functional coactivation based on L2 orthographic depth.…”

“…Interestingly, studies supporting a prelexical computational role of the vOT have mainly used low-level reading tasks (e.g., passive silent reading; Cohen et al 2002;Dehaene et al 2010;Pegado et al 2011) whereas most of the studies favoring an interactive account of the vOT have used high-level reading tasks (e.g., lexical decision; Twomey et al 2011;Woollams et al 2011;Seghier and Price 2013).…”

Impaired integration of object knowledge and visual input in a case of ventral simultanagnosia with bilateral damage to area V4

“…Evidence of interactions between sensory input and prior knowledge during perception has been found in a variety of domains including, for example, attentional modulation of neuronal responses in early visual cortex (e.g., Ito & Gilbert, 1999;Luck et al,1997;Moran & Desimone, 1985), letter identification and lexical access (e.g., McClelland & Rumelhart, 1981;Smith & Besner, 2001;Twomey et al, 2011), eye movement control during scene inspection (e.g., Foulsham & Underwood, 2007), and object grouping effects on visual crowding (Pelli, 2008;Saarela, Sayim, Westheimer & Herzog;.…”

Colateralization of Broca’s area and the visual word form area in left-handers: fMRI evidence

“…Others believe that the vOT is not dedicated to visual word form processing because it also responds to picture naming, repeating auditory words etc. (e.g., Devlin, Jamison, Gonnerman & Matthews, 2006;Duncan, Pattamadilok & Devlin, 2010;Price & Devlin, 2003Twomey, Duncan, Price & Devlin, 2011). The latter view considers the 1 Note that the direction of laterality within an activated region can be influenced by both excitatory and inhibitory connections from the LH/RH homologue areas.…”