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

Reading is a uniquely human skill, learned through extensive experience during childhood, with literacy becoming widespread only in the past few hundred years. Consequently, the neural circuitry underlying language could not have evolved to have circuitry genetically predefined for reading; this is unlike other expert skills such as face recognition, which can be seen in some of our evolutionary ancestors. Therefore, understanding the nature of the reading circuit strikes at the heart of the nature versus nurture debate about how expert skills shape, and are shaped by, brain circuitry. The PNAS article by Lerma-Usabiaga et al. (1) focuses on understanding the specialization of a particular brain territory, the left ventral occipitotemporal cortex (vOTC), known to be critical for visual word recognition. The study uses a combination of magnetic resonance imaging (MRI) and behavioral methods to carefully dissect two functionally and structurally distinct regions located within the vOTC that contribute to reading. Lerma-Usabiaga et al. (1) were motivated by previous studies that have used functional MRI to localize the “visual word form area” (VWFA). Conceptually, the VWFA is a brain region within the left vOTC that responds preferentially to printed words and word-like stimuli. This orthographic selectivity emerges with the acquisition of literacy, indicating that reading experience tunes this region for skilled reading (2). Indeed, individuals with poorer reading ability exhibit reduced selectivity in the vOTC (3), and damage in adulthood causes acquired alexia, in which printed words can no longer be recognized automatically (4). While researchers agree on these broad facts about the VWFA, they disagree on the precise location of the VWFA and its specific role in reading (4⇓–6). These disagreements could arise because different types of stimulus comparisons weight differentially for perceptual versus linguistic aspects of visual word recognition. Thus, like the proverbial men … [↵][1]1To whom correspondence should be addressed. Email: fiez{at}pitt.edu. [1]: #xref-corresp-1-1

Automatic activation of phonology in visual word recognition has been well documented. It has been attributed, at least in part, to the sequential development of speech and literacy which results in the tendency for children to match orthographical input to phonological representation at the early stages of literacy development (e.g., Bosman & De Groot, 1996; Davis, Castles, & Iakovidis, 1998; Goswami, 1993). In contrast to the development of speech prior to literacy in first language (L1) acquisition, second language (L2) learners typically learn to speak and read at the same time. This raises the question of whether phonology is also automatically activated in L2 reading. This issue was investigated in this study by exploring the pseudohomophone effect in L2 reading using a lexical decision task. The role of learners’ L1 was also examined by including both alphabetic and non-alphabetic learners of English as L2. A strong pseudohomophone effect was found in reaction time among native English speakers and alphabetic non-native speakers. Non-alphabetic learners, however, showed a pseudohomophone effect in error rate but not in reaction time. The findings were discussed in terms of how learning experiences and L1 background affect phonological activation in visual L2 word recognition.

EEG has been central to investigations of the time course of various neural functions underpinning visual word recognition. Recently the steady-state visual evoked potential (SSVEP) paradigm has been increasingly adopted for word recognition studies due to its high signal-to-noise ratio. Such studies, however, have been typically framed around a single source in the left ventral occipitotemporal cortex (vOT). Here, we combine SSVEP recorded from 16 adult native English speakers with a data-driven spatial filtering approach—Reliable Components Analysis (RCA)—to elucidate distinct functional sources with overlapping yet separable time courses and topographies that emerge when contrasting words with pseudofont visual controls. The first component topography was maximal over left vOT regions with a shorter latency (approximately 180 ms). A second component was maximal over more dorsal parietal regions with a longer latency (approximately 260 ms). Both components consistently emerged across a range of parameter manipulations including changes in the spatial overlap between successive stimuli, and changes in both base and deviation frequency. We then contrasted word-in-nonword and word-in-pseudoword to test the hierarchical processing mechanisms underlying visual word recognition. Results suggest that these hierarchical contrasts fail to evoke a unitary component that might be reasonably associated with lexical access.

To what extent does semantic information play a functional role in visual word recognition? Theories of word recognition vary in the importance assigned to semantic information in visual lexical decision, with past research suggesting that the nature of the foils is a crucial determinant of semantic reliance. Here, we explored the conditions under which semantic variables influence lexical decision. Normal readers performed visual lexical decision tasks in which imageability and semantic priming were manipulated, with nonword foils varying systematically in their orthographic and phonological similarity to the real words. The effects of imageability and semantic priming increased in magnitude as nonword foils became progressively more wordlike. These findings provide a clear illustration of the flexible use of semantic information to support normal visual word recognition.

The neural/mental operations involved in the process of visual word recognition (VWR) are fundamental for the efficient comprehension of written/printed words during reading. The present study used CiteSpace, a visual analysis software, to identify the intellectual landscape where VWR has been reviewed in the past decade. Thus, synthesized co-citation networks were analyzed to explore and discuss the main questions raised in the VWR literature: the research fronts and the emerging trends of research on this topic. Our results showed that the main questions addressed in VWR studies during the last decade have been focused on four main aspects related to "what," "where," "when," and "how" of VWR; to be specific, the different types of representations assessed during VWR ("what"), the locations and the timing of the brain activity involved in VWR ("where" and "when"), and the interactivity among different representations during processing ("how"). Among the revised studies, letter position coding was found to be the main topic of interest, possibly reflecting the critical role of this process. Furthermore, the evidence found in these studies consistently supported that VWR implies access to phonological, semantic, and morphological representations, which interact and modulate the processing of written words, particularly during early stages. Altogether, our findings showed the evolution in VWR literature regarding the different cognitive and neural operations involved in this process, highlighting the growing interest over the last decade toward the top-down way that mental representations interact.

The reading comprehension and visual word recognition in 50 deaf children and adolescents with at least 3 years of cochlear implant (CI) use were evaluated. Their skills were contrasted with reference data of 500 deaf children without CIs. The reading comprehension level in children with CIs was expected to surpass that in deaf children without implants, partly via improved visual word recognition. Reading comprehension scores of children with implants were significantly better than those of deaf children without implants, although the performance in implant users was substantially lagging behind that in hearing children. Visual word recognition was better in children with CIs than in children without implants, in secondary education only. No difference in visual word recognition was found between the children with CIs and the hearing children, whereas the deaf children without implants showed a slightly poorer performance. The difference in reading comprehension performance of the deaf children with and without CIs remained present when visual word recognition was controlled for. This indicates that other reading-related skills were also contributing to the improved reading comprehension skills of deaf children with CIs.

Aging, alzheimer's disease, and word recognition: A review of the recent literature

The present study investigated the representation and processing of segmental and tonal information in visual Chinese word recognition in native and non‐native Chinese readers. Two experiments using homophone judgement paradigm were conducted. When judging two Chinese characters (Experiment 1), both groups showed difficulties when the segmental but not tonal information was shared (i.e., S+T− condition), with stronger interference for non‐native readers. When judging a Pinyin and a Chinese character (Experiment 2), non‐native readers' S+T− disadvantage was significantly reduced. Finally, when their L1s share the Latin alphabets with Pinyin, the participants showed stronger segmental reliance compared with the native readers. These findings suggest that while both native and non‐native readers rely more on segmental information in Chinese visual word recognition, this reliance is stronger among non‐native readers. Furthermore, the alphabetic nature of the Pinyin orthography may help non‐native readers' phonological representation and processing in a nonalphabetic writing system.

Functional dissociation of the left ventral occipito-temporal cortex in the direct and indirect retrieval of color features

The present study investigated the role of cognitive control on semantic information during visual word recognition by exploiting taboo stimuli in a lexical-decision task. We relied on delta plots and electromyography (EMG) to assess different hypothetical mechanisms of cognitive control. Previous research suggests that taboo stimuli slow down the performance across a variety of tasks due to their attention-grabbing nature. One possibility is that cognitive control counteracts the detrimental effects of taboo connotation by actively dampening such prepotent yet task-irrelevant information. Consistent with this hypothesis, we found a reversal of taboo interference effect in slowest responses, signaling the deployment of a selective suppression mechanism that needs time to fully accrue. For electromyographic data, we focused on partial errors (trials showing a subthreshold activation of the incorrect response hand) to index response-monitoring processes intervening to prevent and correct errors. We found no modulation of the likelihood of partial errors and, more generally, of response accuracy as a function of taboo connotation. Taken together, the results suggest that cognitive control may intervene to selectively suppress fast-acting and distracting taboo information, indicating a controlled semantic processing that optimizes activation to match task-relevant goals. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

We investigated whether semantic interference occurring during visual word recognition is resolved using domain-general control mechanisms or using more specific mechanisms related to semantic processing. We asked participants to perform a lexical decision task with taboo stimuli, which induce semantic interference, as well as a semantic Stroop task and a Simon task, intended as benchmarks of linguistic-semantic and non-linguistic interference, respectively. Using a correlational approach, we investigated potential similarities between effects produced in the three tasks, both at the level of overall means and as a function of response speed (delta-plot analysis). Correlations selectively surfaced between the lexical decision and the semantic Stroop task. These findings suggest that, during visual word recognition, semantic interference is controlled by semantic-specific mechanisms, which intervene to face prepotent but task-irrelevant semantic information interfering with the accomplishment of the task's goal.

Reading involves mapping combinations of a learned visual code (letters) onto meaning. Previous studies have shown that when visual word recognition is challenged by visual degradation, one way to mitigate these negative effects is to provide "top–down" contextual support through a written congruent sentence context. Crowding is a naturally occurring visual phenomenon that impairs object recognition and also affects the recognition of written stimuli during reading. Thus, access to a supporting semantic context via a written text is vulnerable to the detrimental impact of crowding on letters and words. Here, we suggest that an auditory sentence context may provide an alternative source of semantic information that is not influenced by crowding, thus providing “top–down” support cross-modally. The goal of the current study was to investigate whether adult readers can cross-modally compensate for crowding in visual word recognition using an auditory sentence context. The results show a significant cross-modal interaction between the congruency of the auditory sentence context and visual crowding, suggesting that interactions can occur across multiple levels of processing and across different modalities to support reading processes. These findings highlight the need for reading models to specify in greater detail how top–down, cross-modal and interactive mechanisms may allow readers to compensate for deficiencies at early stages of visual processing.

We report a comprehensive cartography of selective responses to visual letters and words in the human ventral occipito-temporal cortex (VOTC) with direct neural recordings, clarifying key aspects of the neural basis of reading. Intracerebral recordings were performed in a large group of patients (n = 37) presented with visual words inserted periodically in rapid sequences of pseudofonts, nonwords, or pseudowords, enabling classification of responses at three levels of word processing: letter, prelexical, and lexical. While letter-selective responses are found in much of the VOTC, with a higher proportion in left posterior regions, prelexical/lexical responses are confined to the middle and anterior sections of the left fusiform gyrus. This region overlaps with and extends more anteriorly than the visual word form area typically identified with functional magnetic resonance imaging. In this region, prelexical responses provide evidence for populations of neurons sensitive to the statistical regularity of letter combinations independently of lexical responses to familiar words. Despite extensive sampling in anterior ventral temporal regions, there is no hierarchical organization between prelexical and lexical responses in the left fusiform gyrus. Overall, distinct word processing levels depend on neural populations that are spatially intermingled rather than organized according to a strict postero-anterior hierarchy in the left VOTC.

IntroductionThe current study investigated the influence of the number of meanings on visual word recognition, with a particular focus on hemispheric dynamics.MethodsBy reanalyzing parafoveal Korean lexical decision data, we examined how words with a high versus low number of meanings affect right visual field advantage (RVFA) and bilateral redundancy gain (BRG).ResultsThe words with a greater number of meanings exhibited a stronger RVFA and reduced BRG compared to words with fewer meanings.DiscussionThe findings suggest that the facilitatory effects associated with multiple meanings are more pronounced in the left hemisphere (LH) than in the right hemisphere (RH). Furthermore, the increased lateralization of processing within the LH appears to diminish the need for interhemispheric interactions, leading to decreased coordination between the hemispheres. These results imply that the number of meanings in words shapes interhemispheric dynamics during visual word recognition. The implications of these findings are discussed in relation to theoretical models of visual word recognition and hemispheric differences in language processing.

An Event-Related Potential study of letter spacing during visual word recognition