Timing the impact of literacy on visual processing

Hemispheric dominance in reading system alters contribution to face processing lateralization across development

Face processing dominates the right hemisphere. This lateralization can be affected by co-lateralization within the same system and influence between different systems, such as neural competition from reading acquisition. Yet, how the relationship pattern changes through development remains unknown. This study examined the lateralization of core face processing and word processing in different age groups. By comparing fMRI data from 36 school-aged children and 40 young adults, we investigated whether there are age and regional effects on lateralization, and how relationships between lateralization within and between systems change across development. Our results showed significant right hemispheric lateralization in the core face system and left hemispheric lateralization in reading-related areas for both age groups when viewing faces and texts passively. While all participants showed stronger lateralization in brain regions of higher functional hierarchy when viewing faces, only adults exhibited this lateralization when viewing texts. In both age cohorts, there was intra-system co-lateralization for face processing, whereas an inter-system relationship was only found in adults. Specifically, functional lateralization of Broca's area during reading negatively predicted functional asymmetry in the FFA during face perception. This study initially provides neuroimaging evidence for the reading-induced neural competition theory from a maturational perspective in Chinese cohorts.

Letters away from the looking glass: Developmental trajectory of mirrored and rotated letter processing within words

Discrimination of reversible mirrored letters (e.g., d and b) poses a challenge when learning to read as it requires overcoming mirror invariance, an evolutionary-old perceptual tendency of processing mirror images as equivalent. The present study investigated when, in reading development, mirror-image discrimination becomes automatic during visual word recognition. The developmental trajectory of masked priming effects was investigated from 2nd to 6th grade and in adults, by manipulating letter type (nonreversible; reversible) and prime condition (control; identity; mirrored; rotated). Standardized identity priming increased along reading development. Beginning readers showed mirror invariance during reversible and nonreversible letter processing. A mirror cost (slower word recognition in mirrored-letter than identity prime condition) was found by 5th-grade but only for reversible letters. By 6th grade, orthographic processing was no longer captive of mirror invariance. A multiple linear regression showed that letter representations, but not phonological processes or age, were a reliable predictor of the rise of mirror-image discrimination in 2nd-4th-graders. The present results suggest a protracted development of automatic mirror-image discrimination during orthographic processing, contingent upon the quality of abstract letter representations. RESEARCH HIGHLIGHTS: We traced the developmental trajectory of mirrored-letter and rotated-letter priming effects (e.g., ibea and ipea as primes of IDEA) in visual word recognition. Beginning readers (2nd-4th-graders) showed mirror invariance and plane-rotation sensitivity in orthographic processing, thus still being susceptible to the perceptual biases in charge in object recognition. A mirror cost was found in 5th-graders but only for reversible letters; orthographic processing was no longer captive of mirror invariance by 6th-grade. The automation of mirror-image discrimination during orthographic processing depends on the quality of letter representations but not on phonological processes or age.

Development of the mirror-image sensitivity for different object categories-Evidence from the mirror costs of object images in children and adults

Object recognition relies on a multitude of factors, including size, orientation, and so on. Mirrored orientation, particularly due to children's mirror confusion in reading, holds special significance among various object orientations. Brain imaging studies suggest that the visual ventral and dorsal streams exhibit distinct orientation sensitivity across diverse object categories. Yet, it remains unclear whether mirror orientation sensitivity also varies among these categories during development at the behavioral level. Here, we explored the mirror sensitivity of children and adults across five distinct categories, which encompass tools that activate both the visual ventral stream for function information and the dorsal stream for manipulation information, and animals and faces that mainly activate the ventral stream. Two types of symbols, letters and Chinese characters, were also included. Mirror sensitivity was assessed through mirror costs-that is, the additional reaction time or error rate in the mirrored versus the same orientation condition when judging the identity of object pairs. The mirror costs in reaction times and error rates consistently revealed that children exhibited null mirror costs for tools, and the mirror costs for tools in adults were minimal, if any, and were smaller than those for letters and characters. The mirror costs reflected in absolute reaction time and error rate were similar across adults and children, but when the overall difference in reaction times was considered, adults showed a larger mirror cost than children. Overall, our investigation unveils categorical distinctions and development in mirror sensitivity of object recognition across the ventral and dorsal streams.

Beyond the Visual Word Form Area - a cognitive characterization of the left ventral occipitotemporal cortex

The left ventral occipitotemporal cortex has been traditionally viewed as a pathway for visual object recognition including written letters and words. Its crucial role in reading was strengthened by the studies on the functionally localized "Visual Word Form Area" responsible for processing word-like information. However, in the past 20 years, empirical studies have challenged the assumptions of this brain region as processing exclusively visual or even orthographic stimuli. In this review, we aimed to present the development of understanding of the left ventral occipitotemporal cortex from the visually based letter area to the modality-independent symbolic language related region. We discuss theoretical and empirical research that includes orthographic, phonological, and semantic properties of language. Existing results showed that involvement of the left ventral occipitotemporal cortex is not limited to unimodal activity but also includes multimodal processes. The idea of the integrative nature of this region is supported by the broad functional and structural connectivity with language-related and attentional brain networks. We conclude that although the function of the area is not yet fully understood in human cognition, its role goes beyond visual word form processing. The left ventral occipitotemporal cortex seems to be crucial for combining higher-level language information with abstract forms that convey meaning independently of modality.

The Role of Neural and Genetic Processes in Learning to Read and Specific Reading Disabilities: Implications for Instruction

To learn to read, the brain must repurpose neural systems for oral language and visual processing to mediate written language. We begin with a description of computational models for how alphabetic written language is processed. Next, we explain the roles of a dorsal sublexical system in the brain that relates print and speech, a ventral lexical system that develops the visual expertise for rapid orthographic processing at the word level, and the role of cognitive control networks that regulate attentional processes as children read. We then use studies of children, adult illiterates learning to read, and studies of poor readers involved in intervention, to demonstrate the plasticity of these neural networks in development and in relation to instruction. We provide a brief overview of the rapid increase in the field's understanding and technology for assessing genetic influence on reading. Family studies of twins have shown that reading skills are heritable, and molecular genetic studies have identified numerous regions of the genome that may harbor candidate genes for the heritability of reading. In selected families, reading impairment has been associated with major genetic effects, despite individual gene contributions across the broader population that appear to be small. Neural and genetic studies do not prescribe how children should be taught to read, but these studies have underscored the critical role of early intervention and ongoing support. These studies also have highlighted how structured instruction that facilitates access to the sublexical components of words is a critical part of training the brain to read.

The multiple-level framework of developmental dyslexia: the long trace from a neurodevelopmental deficit to an impaired cultural technique

Developmental dyslexia is a neurodevelopmental disorder characterized by an unexpected impairment in literacy acquisition leading to specific poor academic achievement and possible secondary symptoms. The multi-level framework of developmental dyslexia considers five levels of a causal pathway on which a given genotype is expressed and hierarchically transmitted from one level to the next under the increasing influence of individual learning-relevant traits and environmental factors moderated by cultural conditions. These levels are the neurobiological, the information processing and the skill level (prerequisites and acquisition of literacy skills), the academic achievement level and the level of secondary effects. Various risk factors are present at each level within the assumed causal pathway and can increase the likelihood of exhibiting developmental dyslexia. Transition from one level to the next is neither unidirectional nor inevitable. This fact has direct implications for prevention and intervention which can mitigate transitions from one level to the next. In this paper, various evidence-based theories and findings regarding deficits at different levels are placed in the proposed framework. In addition, the moderating effect of cultural impact at and between information processing and skill levels are further elaborated based on a review of findings regarding influences of different writing systems and orthographies. These differences impose culture-specific demands for literacy-specific cognitive procedures, influencing both literacy acquisition and the manifestation of developmental dyslexia.

The inhibition of mirror generalization of letters in school-aged children

Gender differences in spatial abilities favor males in both childhood and adulthood. During early development, this discrepancy can be attributed, among other things, to the influence of an early testosterone surge in boys, societal stereotypes, and expectations about gender. In the present work, we created a spatial task (including letter rotation and letter mirroring) which used letters as stimuli and evaluated the performance of school-aged children (6-10 years old). During this age period, children are being taught literacy skills which rely on the reorganization of cortical networks and the breakdown of mirror generalization. We divided our sample (N = 142, 73 females) into two age groups: 1^st-2^nd (literacy acquisition; N = 70, 33 females) and 3^rd-5^th (literacy consolidation; N = 72, 40 females) graders. While boys performed significantly better in letter rotation in the older group, girls' performance remained substandard in both groups. This pattern is reversed for the mirror task, with older girls outperforming their younger counterparts and boys having similar performance in the two groups. Since the age period of our sample is not associated with large variations in the levels of reproductive steroids, we propose that the similarity of performance between younger and older girls in mental rotation of letters could be associated with society's traditional attitudes and expectations on the relationship between visual-spatial skills and gender. As for the mirror task, while only girls had a significant difference between the two age groups, boys did show an improvement, as expected for the inhibition of mirror generalization for letters during reading acquisition.

Lateralization of orthographic processing in fixed-gaze and natural reading conditions

Lateralized processing of orthographic information is a hallmark of proficient reading. However, how this finding obtained for fixed-gaze processing of orthographic stimuli translates to ecologically valid reading conditions remained to be clarified. To address this shortcoming, here we assessed the lateralization of early orthographic processing in fixed-gaze and natural reading conditions using concurrent eye-tracking and EEG data recorded from young adults without reading difficulties. Sensor-space analyses confirmed the well-known left-lateralized negative-going deflection of fixed-gaze EEG activity throughout the period of early orthographic processing. At the same time, fixation-related EEG activity exhibited left-lateralized followed by right-lateralized processing of text stimuli during natural reading. A strong positive relationship was found between the early leftward lateralization in fixed-gaze and natural reading conditions. Using source-space analyses, early left-lateralized brain activity was obtained in lateraloccipital and posterior ventral occipito-temporal cortices reflecting letter-level processing in both conditions. In addition, in the same time interval, left-lateralized source activity was found also in premotor and parietal brain regions during natural reading. While brain activity remained left-lateralized in later stages representing word-level processing in posterior and middle ventral temporal regions in the fixed-gaze condition, fixation-related source activity became stronger in the right hemisphere in medial and more anterior ventral temporal brain regions indicating higher-level processing of orthographic information. Although our results show a strong positive relationship between the lateralization of letter-level processing in the two reading modes and suggest lateralized brain activity as a general marker for processing of orthographic information, they also clearly indicate the need for reading research in ecologically valid conditions to identify the neural basis of visuospatial attentional, oculomotor and higher-level processes specific to natural reading.

The visual-attention span deficit in developmental dyslexia: Review of evidence for a visual-attention-based deficit

The visual attention span (VAS) deficit hypothesis in developmental dyslexia posits that a subset of dyslexic individuals shows a multielement parallel processing deficit due to reduced visual attention capacity. However, the attention-based interpretation of poor performance on VAS tasks is hotly debated. The purpose of the present paper is to clarify this issue through a critical review of relevant behavioural and neurobiological findings. We first examine the plausibility of alternative verbal interpretations of VAS performance, evaluating whether performance on VAS tasks might reflect verbal short-term memory, verbal coding or visual-to-verbal mapping skills. We then focus on the visual dimensions of VAS tasks to question whether VAS primarily reflects visuo-attentional rather than more basic visual skills. Scrutiny of the available behavioural and neurobiological findings not only points to a deficit of visual attention in dyslexic individuals with impaired VAS but further suggests a selective endogenous attentional system deficit that relates to atypical functioning of the brain dorsal attentional network. The overview clarifies the debate on what is being measured through VAS tasks and provides insights on how to interpret the VAS deficit in developmental dyslexia.

Neural sensitivity to faces is increased by immersion into a novel ethnic environment: Evidence from ERPs

Previous reports suggest that East-Asians may show larger face-elicited N170 components in the ERP as compared to Caucasian participants. Since the N170 can be modulated by perceptual expertise, such group differences may be accounted for by differential experience, for example, with logographic versus alphabetic scripts (script system hypothesis) or by exposure to abundant novel faces during the immersion into a new social and/or ethnic environment (social immersion hypothesis). We conducted experiments in Hong Kong and Berlin, recording ERPs in a series of one-back tasks, using same- and other-ethnicity face stimuli in upright and inverted orientation and doodle stimuli. In Hong Kong we tested local Chinese residents and foreign guest students who could not read the logographic script; in Berlin we tested German residents who could not read the logographic script and foreign Chinese visitors. In both experiments, we found significantly larger N170 amplitudes to faces, regardless of ethnicity, in the foreign than in the local groups. Moreover, this effect did not depend on stimulus orientation, suggesting that the N170 group differences do not reflect differences in configural visual processing. A group of short-term German residents in Berlin did not differ in N170 amplitude from long-term residents. Together, these findings indicate that the extensive confrontation with novel other-ethnicity faces during immersion in a foreign culture may enhance the neural response to faces, reflecting the short-term plasticity of the underlying neural system.

Typical and Atypical Development of Visual Expertise for Print as Indexed by the Visual Word N1 (N170w): A Systematic Review

The visual word N1 (N170w) is an early brain ERP component that has been found to be a neurophysiological marker for print expertise, which is a prelexical requirement associated with reading development. To date, no other review has assimilated existing research on reading difficulties and atypical development of processes reflected in the N170w response. Hence, this systematic review synthesized results and evaluated neurophysiological and experimental procedures across different studies about visual print expertise in reading development. Literature databases were examined for relevant studies from 1995 to 2020 investigating the N170w response in individuals with or without reading disorders. To capture the development of the N170w related to reading, results were compared between three different age groups: pre-literate children, school-aged children, and young adults. The majority of available N170w studies (N = 69) investigated adults (n = 31) followed by children (school-aged: n = 21; pre-literate: n = 4) and adolescents (n = 1) while some studies investigated a combination of these age groups (n = 12). Most studies were conducted with German-speaking populations (n = 17), followed by English (n = 15) and Chinese (n = 14) speaking participants. The N170w was primarily investigated using a combination of words, pseudowords, and symbols (n = 20) and mostly used repetition-detection (n = 16) or lexical-decision tasks (n = 16). Different studies posed huge variability in selecting electrode sites for analysis; however, most focused on P7, P8, and O1 sites of the international 10–20 system. Most of the studies in adults have found a more negative N170w in controls than poor readers, whereas in children, the results have been mixed. In typical readers, N170w ranged from having a bilateral distribution to a left-hemispheric dominance throughout development, whereas in young, poor readers, the response was mainly right-lateralized and then remained in a bilateral distribution. Moreover, the N170w latency has varied according to age group, with adults having an earlier onset yet with shorter latency than school-aged and pre-literate children. This systematic review provides a comprehensive picture of the development of print expertise as indexed by the N170w across age groups and reading abilities and discusses theoretical and methodological differences and challenges in the field, aiming to guide future research.

Written Language Acquisition Is Both Shaped by and Has an Impact on Brain Functioning and Cognition

Spoken language is a distinctive trace of our species and it is naturally acquired during infancy. Written language, in contrast, is artificial, and the correspondences between arbitrary visual symbols and the spoken language for reading and writing should be explicitly learned with external help. In this paper, I present several examples of how written language acquisition is both shaped by and has an impact on brain function and cognition. They show in one hand how our phylogenetic legacy influences education and on the other hand how ontogenetic needs for education can rapidly subdue deeply rooted neurocognitive mechanisms. The understanding of this bidirectional influences provides a more dynamic view of how plasticity interfaces phylogeny and ontogeny in human learning, with implications for both neurosciences and education.

Evolution of reading and face circuits during the first three years of reading acquisition

Although words and faces activate neighboring regions in the fusiform gyrus, we lack an understanding of how such category selectivity emerges during development. To investigate the organization of reading and face circuits at the earliest stage of reading acquisition, we measured the fMRI responses to words, faces, houses, and checkerboards in three groups of 60 French children: 6-year-old pre-readers, 6-year-old beginning readers and 9-year-old advanced readers. The results showed that specific responses to written words were absent prior to reading, but emerged in beginning readers, irrespective of age. Likewise, specific responses to faces were barely visible in pre-readers and continued to evolve in the 9-year-olds, yet primarily driven by age rather than by schooling. Crucially, the sectors of ventral visual cortex that become specialized for words and faces harbored their own functional connectivity prior to reading acquisition: the VWFA with left-hemispheric spoken language areas, and the FFA with the contralateral region and the amygdalae. The results support the view that reading acquisition occurs through the recycling of a pre-existing but plastic circuit which, in pre-readers, already connects the VWFA site to other distant language areas. We argue that reading acquisition does not compete with the face system directly, through a pruning of preexisting face responses, but indirectly, by hindering the slow growth of face responses in the left hemisphere, thus increasing a pre-existing right hemispheric bias.

Lateralization of early orthographic processing during natural reading is impaired in developmental dyslexia

Skilled reading requires specialized visual cortical processing of orthographic information and its impairment has been proposed as a potential correlate of compromised reading in dyslexia. However, which stage of orthographic information processing during natural reading is disturbed in dyslexics remains unexplored. Here we addressed this question by simultaneously measuring the eye movements and EEG of dyslexic and control young adults during natural reading. Isolated meaningful sentences were presented at five inter-letter spacing levels spanning the range from minimal to extra-large spacing, and participants were instructed to read the text silently at their own pace. Control participants read faster, performed larger saccades and shorter fixations compared to dyslexics. While reading speed peaked around the default letter spacing, saccade amplitude increased and fixation duration decreased with the increase of letter spacing in both groups. Lateralization of occipito-temporal fixation-related EEG activity (FREA) was found in three consecutive time intervals corresponding to early orthographic processing in control readers. Importantly, the lateralization in the time range of the first negative left occipito-temporal FREA peak was specific for first fixations and exhibited an interaction effect between reading ability and letter spacing. The interaction originated in the significant decrease of FREA lateralization at extra-large compared to default letter spacing in control readers and the lack of lateralization in both letter spacing conditions in the case of dyslexics. These findings suggest that expertise-driven hemispheric functional specialization for early orthographic processing thought to be responsible for letter identity extraction during natural reading is compromised in dyslexia.

Predicting Reading From Behavioral and Neural Measures - A Longitudinal Event-Related Potential Study

Fluent reading is characterized by fast and effortless decoding of visual and phonological information. Here we used event-related potentials (ERPs) and neuropsychological testing to probe the neurocognitive basis of reading in a sample of children with a wide range of reading skills. We report data of 51 children who were measured at two time points, i.e., at the end of first grade (mean age 7.6 years) and at the end of fourth grade (mean age 10.5 years). The aim of this study was to clarify whether next to behavioral measures also basic unimodal and bimodal neural measures help explaining the variance in the later reading outcome. Specifically, we addressed the question of whether next to the so far investigated unimodal measures of N1 print tuning and mismatch negativity (MMN), a bimodal measure of audiovisual integration (AV) contributes and possibly enhances prediction of the later reading outcome. We found that the largest variance in reading was explained by the behavioral measures of rapid automatized naming (RAN), block design and vocabulary (46%). Furthermore, we demonstrated that both unimodal measures of N1 print tuning (16%) and filtered MMN (7%) predicted reading, suggesting that N1 print tuning at the early stage of reading acquisition is a particularly good predictor of the later reading outcome. Beyond the behavioral measures, the two unimodal neural measures explained 7.2% additional variance in reading, indicating that basic neural measures can improve prediction of the later reading outcome over behavioral measures alone. In this study, the AV congruency effect did not significantly predict reading. It is therefore possible that audiovisual congruency effects reflect higher levels of multisensory integration that may be less important for reading acquisition in the first year of learning to read, and that they may potentially gain on relevance later on.

Emergence of a compositional neural code for written words: Recycling of a convolutional neural network for reading

The visual word form area (VWFA) is a region of human inferotemporal cortex that emerges at a fixed location in the occipitotemporal cortex during reading acquisition and systematically responds to written words in literate individuals. According to the neuronal recycling hypothesis, this region arises through the repurposing, for letter recognition, of a subpart of the ventral visual pathway initially involved in face and object recognition. Furthermore, according to the biased connectivity hypothesis, its reproducible localization is due to preexisting connections from this subregion to areas involved in spoken-language processing. Here, we evaluate those hypotheses in an explicit computational model. We trained a deep convolutional neural network of the ventral visual pathway, first to categorize pictures and then to recognize written words invariantly for case, font, and size. We show that the model can account for many properties of the VWFA, particularly when a subset of units possesses a biased connectivity to word output units. The network develops a sparse, invariant representation of written words, based on a restricted set of reading-selective units. Their activation mimics several properties of the VWFA, and their lesioning causes a reading-specific deficit. The model predicts that, in literate brains, written words are encoded by a compositional neural code with neurons tuned either to individual letters and their ordinal position relative to word start or word ending or to pairs of letters (bigrams).

Is human face recognition lateralized to the right hemisphere due to neural competition with left-lateralized visual word recognition? A critical review

The right hemispheric lateralization of face recognition, which is well documented and appears to be specific to the human species, remains a scientific mystery. According to a long-standing view, the evolution of language, which is typically substantiated in the left hemisphere, competes with the cortical space in that hemisphere available for visuospatial processes, including face recognition. Over the last decade, a specific hypothesis derived from this view according to which neural competition in the left ventral occipito-temporal cortex with selective representations of letter strings causes right hemispheric lateralization of face recognition, has generated considerable interest and research in the scientific community. Here, a systematic review of studies performed in various populations (infants, children, literate and illiterate adults, left-handed adults) and methodologies (behavior, lesion studies, (intra)electroencephalography, neuroimaging) offers little if any support for this reading lateralized neural competition hypothesis. Specifically, right-lateralized face-selective neural activity already emerges at a few months of age, well before reading acquisition. Moreover, consistent evidence of face recognition performance and its right hemispheric lateralization being modulated by literacy level during development or at adulthood is lacking. Given the absence of solid alternative hypotheses and the key role of neural competition in the sensory-motor cortices for selectivity of representations, learning, and plasticity, a revised language-related neural competition hypothesis for the right hemispheric lateralization of face recognition should be further explored in future research, albeit with substantial conceptual clarification and advances in methodological rigor.

Face processing predicts reading ability: Evidence from prosopagnosia

There is considerable interest in whether face and word processing are reliant upon shared or dissociable processes. Developmental prosopagnosia is associated with lifelong face processing deficits, with these cases providing strong support for a dissociation between face and word recognition in three recent papers (Burns et al., 2017; Rubino et al., 2016; Starrfelt et al., 2018). However, the sample sizes in each of these studies may have been too small to detect significant effects. We therefore combined their data to increase power and reassessed their results. While only a non-significant trend for reading impairments was found in prosopagnosia using a one-sample t-test, poorer face memory performance was correlated with slower reading speeds across prosopagnosia and control participants. Surprisingly, poorer face perception skills in prosopagnosia were associated with smaller word length effects. This suggests that while mild reading impairments exist in developmental prosopagnosia, there may be a trade-off between their residual face perception abilities and reading skill. A reanalysis of Hills and colleagues' (2015) acquired prosopagnosia data also revealed a positive relationship between words and faces: severe impairments in face recognition were related to poorer word processing. In summary, the developmental and acquired prosopagnosia literature supports models of visual perception that posit face and word processing are reliant upon broadly shared processes.

A protocol to examine the learning effects of 'multisystem mapping' training combined with post-training sleep consolidation in beginning readers

We have recently used randomized controlled trials to examine the impact of a short neuroscience-informed causal intervention using a targeted training to inhibit a deeply rooted visual mechanism (mirror invariance) that hinders literacy acquisition, combined with post-training sleep (for learning consolidation). Using this training protocol, we have shown unprecedented improvements in visual perception of letters, writing, and a two-fold increase in reading fluency in first graders. Here, we describe this ecologically valid school-based intervention protocol to probe inhibition of mirror invariance for letters, including the detailed training instructions, post-training sleep consolidation, as well as practical tips and potential adaptations to different school sizes. For complete details on the use and execution of this protocol, please refer to Torres et al., (2021).

Selective Inhibition of Mirror Invariance for Letters Consolidated by Sleep Doubles Reading Fluency

Mirror invariance is a visual mechanism that enables a prompt recognition of mirror images. This visual capacity emerges early in human development, is useful to recognize objects, faces, and places from both left and right perspectives, and is also present in primates, pigeons, and cephalopods. Notwithstanding, the same visual mechanism has been suspected to be the source of a specific difficulty for a relatively recent human invention-reading-by creating confusion between mirror letters (e.g., b-d in the Latin alphabet). Using an ecologically valid school-based design, we show here that mirror invariance represents indeed a major leash for reading fluency acquisition in first graders. Our causal approach, which specifically targeted mirror invariance inhibition for letters, in a synergic combination with post-training sleep to increase learning consolidation, revealed unprecedented improvement in reading fluency, which became two-times faster. This gain was obtained with as little as 7.5 h of multisensory-motor training to distinguish mirror letters, such as "b" versus "d." The magnitude, automaticity, and duration of this mirror discrimination learning were greatly enhanced by sleep, which keeps the gains perfectly intact even after 4 months. The results were consistently replicated in three randomized controlled trials. They not only reveal an extreme case of cognitive plasticity in humans (i.e., the inhibition in just 3 weeks of a ∼25-million-year-old visual mechanism), that allows adaptation to a cultural activity (reading), but at the same time also show a simple and cost-effective way to unleash the reading fluency potential of millions of children worldwide.

The sound of reading: Color-to-timbre substitution boosts reading performance via OVAL, a novel auditory orthography optimized for visual-to-auditory mapping

Reading is a unique human cognitive skill and its acquisition was proven to extensively affect both brain organization and neuroanatomy. Differently from western sighted individuals, literacy rates via tactile reading systems, such as Braille, are declining, thus imposing an alarming threat to literacy among non-visual readers. This decline is due to many reasons including the length of training needed to master Braille, which must also include extensive tactile sensitivity exercises, the lack of proper Braille instruction and the high costs of Braille devices. The far-reaching consequences of low literacy rates, raise the need to develop alternative, cheap and easy-to-master non-visual reading systems. To this aim, we developed OVAL, a new auditory orthography based on a visual-to-auditory sensory-substitution algorithm. Here we present its efficacy for successful words-reading, and investigation of the extent to which redundant features defining characters (i.e., adding specific colors to letters conveyed into audition via different musical instruments) facilitate or impede auditory reading outcomes. Thus, we tested two groups of blindfolded sighted participants who were either exposed to a monochromatic or to a color version of OVAL. First, we showed that even before training, all participants were able to discriminate between 11 OVAL characters significantly more than chance level. Following 6 hours of specific OVAL training, participants were able to identify all the learned characters, differentiate them from untrained letters, and read short words/pseudo-words of up to 5 characters. The Color group outperformed the Monochromatic group in all tasks, suggesting that redundant characters' features are beneficial for auditory reading. Overall, these results suggest that OVAL is a promising auditory-reading tool that can be used by blind individuals, by people with reading deficits as well as for the investigation of reading specific processing dissociated from the visual modality.

Neural Representation in Visual Word Form Area during Word Reading

The visual word form area (VWFA) has been consistently identified as a crucial structure in visual word processing. Nevertheless, it is controversial whether the VWFA represents external visual information (e.g., case information) of visual words. To address that question, we functionally localized VWFA at the group level (gVWFA) and at the individual level (iVWFA), and used multivariate pattern analysis (MVPA) to explore the information representation in the VWFA during an implicit reading task (i.e., a passive viewing task). Univariate activation analysis revealed that participants showed stronger activations for uppercase English words compared to lowercase ones in the VWFA. MVPA further revealed that the classifier trained based on lowercase words versus letter strings significantly distinguished uppercase words versus letter strings in the iVWFA, while that trained based on lowercase words versus uppercase words distinguished lowercase letter strings versus uppercase letter strings neither in the gVWFA nor in the iVWFA. These results suggest that the VWFA does not represent case information, but represents case-independent linguistic information. Our findings elaborate the function in the VWFA and support the VWFA hypothesis.

From shape to meaning: Evidence for multiple fast feedforward hierarchies of concept processing in the human brain

A number of fMRI studies have provided support for the existence of multiple concept representations in areas of the brain such as the anterior temporal lobe (ATL) and inferior parietal lobule (IPL). However, the interaction among different conceptual representations remains unclear. To better understand the dynamics of how the brain extracts meaning from sensory stimuli, we conducted a human high-density electroencephalography (EEG) study in which we first trained participants to associate pseudowords with various animal and tool concepts. After training, multivariate pattern classification of EEG signals in sensor and source space revealed the representation of both animal and tool concepts in the left ATL and tool concepts within the left IPL within 250 ​ms. Finally, we used Granger Causality analyses to show that orthography-selective sensors directly modulated activity in the parietal-tool selective cluster. Together, our results provide evidence for distinct but parallel "perceptual-to-conceptual" feedforward hierarchies in the brain.

Back-to-back regression: Disentangling the influence of correlated factors from multivariate observations

Identifying causes solely from observations can be particularly challenging when i) the factors under investigation are difficult to manipulate independently from one-another and ii) observations are high-dimensional. To address this issue, we introduce ''Back-to-Back'' regression (B2B), a linear method designed to efficiently estimate, from a set of correlated factors, those that most plausibly account for multidimensional observations. First, we prove the consistency of B2B, its links to other linear approaches, and show how it can provide a robust, unbiased and interpretable scalar estimate for each factor. Second, we use a variety of simulated data to show that B2B can outperform forward modeling ("encoding"), backward modeling ("decoding") as well as cross-decomposition modeling (i.e. canonical correlation analysis and partial least squares) on causal identification when the factors and the observations are not orthogonal. Finally, we apply B2B to a hundred magneto-encephalography recordings and to a hundred functional Magnetic Resonance Imaging recordings acquired while subjects performed a 1 ​h reading task. B2B successfully disentangles the respective contribution of collinear factors such as word length, word frequency in the early visual and late associative cortical responses respectively. B2B compared favorably to other standard techniques on this disentanglement. We discuss how the speed and the generality of B2B sets promising foundations to help identify the causal contributions of covarying factors from high-dimensional observations.

Seeing thought: a cultural cognitive tool

The present paper, which is the first of two twin opinion papers, offers a theoretical approach of literacy and critical literacy in relation to language, thought, and reasoning. Literacy acquisition and practice proceed through two stages, which partially overlap in terms of processing abilities: the first is achieved when the learner becomes a skilled reader and writer, characterized by automatic word processing; the second, when reading comprehension and written production become expert instruments in the communication of progressively more abstract and sophisticated, but always linguistically-mediated, knowledge and ideas. The destiny of literacy, depending on educational and social factors, is thus to be to fused with language, thought and reasoning. Oral language becomes literate language; and our cognitive activity becomes—as indicated in the title—“seeing thought”, which paves the way, we will argue, for reasoning skills. Making of literacy an epistemic and social tool of our own collective history requires a critical stance that raises itself and ourselves to a stage called critical literacy. In this paper we focus on some of the favorable and unfavorable factors influencing this achievement. The main challenge is to bring literate cognition up to the capacity of choosing between accept and verify, between belief and disbelief, by weighting evidence and reasoning, by arguing and debunking errors and falsities. Accordingly, our objective is essentially to narrate how literacy gives birth to critical literacy and explain why, at the end of this process, critical literacy becomes hard to distinguish from thinking and reasoning.

The effects of hemispheric dominance, literacy acquisition, and handedness on the development of visuospatial attention: A study in preschoolers and second graders

A tendency to over-attend the left side of the space (i.e., pseudoneglect) has been repeatedly reported in Western adult populations and is supposed to reflect a right hemisphere dominance in the control of visuospatial attention. This neurobiological hypothesis has been partially challenged by growing evidence showing that pseudoneglect is profoundly triggered by cultural practices such as reading and writing habits. Accordingly, more recent theoretical accounts suggest a strict coupling between nature and nurture dimensions at the origins of such bias. To further explore this possibility, here we first administered a digitized cancellation task to right-handed Western children before and after literacy acquisition. Results showed an incremental leftward shift of attention in the cancellation of the first target and an increasing preference for a left-to-right visual search from preschoolers to second graders. Yet, despite these differences, the overall distribution of visuospatial attention was biased to the left in both groups. To explore the role of handedness in visuospatial asymmetries, we also tested a group of left-handed second graders. Results showed an impact of handedness on visuospatial performance, with an accentuated rightward-oriented visual search for left-handed children, although the overall distribution of attention was again biased to the left hemispace. Taken together, these findings do not provide support to a pure neurobiological view of visuospatial biases. Rather, our study indicates that the control of visuospatial attention is mediated by a dynamic interplay among biological (i.e., right hemisphere dominance), biomechanical (i.e., hand dominance), and cultural (i.e., reading habits) factors.

Simultaneous EEG and fMRI reveals stronger sensitivity to orthographic strings in the left occipito-temporal cortex of typical versus poor beginning readers

The level of reading skills in children and adults is reflected in the strength of preferential neural activation to print. Such preferential activation appears in the N1 event-related potential (ERP) over the occipitotemporal scalp after around 150–250 ms and the corresponding blood oxygen level dependent (BOLD) signal in the ventral occipitotemporal (vOT) cortex. Here, orthography-sensitive (print vs. false font) processing was examined using simultaneous EEG-fMRI in 38 first grade children with poor and typical reading skills, and at varying familial risk for developmental dyslexia. Coarse orthographic sensitivity was observed as an increased activation to print in the N1 ERP and in the BOLD signal of individually varying vOT regions in 57% of beginning readers. Finer differentiation in processing orthographic strings (words vs. nonwords) further occurred in specific vOT clusters. Neither method alone showed robust differences in orthography-sensitive processing between typical and poor reading children. Importantly, using single-trial N1 ERP-informed fMRI analysis, we found differential modulation of the orthography-sensitive BOLD response in the left vOT for typical readers only. This result, thus, confirms subtle functional alterations in a brain structure known to be critical for fluent reading at the very beginning of reading instruction.

The characteristics of face configural effect in illiterates and literates

Literacy acquisition can modulate the way we process visual words and language. However, little is known about its function in reshaping how we process non-linguistic materials, like faces. In this study, we explored this question by comparing the facial recognition skills of illiterate and literate adults in China. Our results showed that illiterates were less sensitive to changes in spatial configuration among key features in upright faces when stimuli were presented simultaneously. The differences in sensitivity of spatial configuration between the literates and illiterates were also observed in house processing. These results thus provide evidence that literacy acquisition during childhood could reshape configural processing.

Early Brain Sensitivity to Word Frequency and Lexicality During Reading Aloud and Implicit Reading

The present study investigated the influence of lexical word properties on the early stages of visual word processing (<250 ms) and how the dynamics of lexical access interact with task-driven top-down processes. We compared the brain's electrical response (event-related potentials, ERPs) of 39 proficient adult readers for the effects of word frequency and word lexicality during an explicit reading task versus a visual immediate-repetition detection task where no linguistic intention is required. In general, we observed that left-lateralized processes linked to perceptual expertise for reading are task independent. Moreover, there was no hint of a word frequency effect in early ERPs, while there was a lexicality effect which was modulated by task demands: during implicit reading, we observed larger N1 negativity in the ERP to real words compared to pseudowords, but in contrast, this modulation by stimulus type was absent for the explicit reading aloud task (where words yielded the same activation as pseudowords). Thus, data indicate that the brain's response to lexical properties of a word is open to influences from top-down processes according to the representations that are relevant for the task, and this occurs from the earliest stages of visual recognition (within ~200 ms). We conjectured that the loci of these early top-down influences identified for implicit reading are probably restricted to lower levels of processing (such as whole word orthography) rather than the process of lexical access itself.

Braille readers break mirror invariance for both visual Braille and Latin letters

For this study, we started from the observation that the poor adequacy of a script to the requirements of the human visual system strongly impacts some aspects of reading expertise (e.g., fluent reading). Here we investigated another of these aspects, namely the ability to break mirror invariance, which makes it hard for readers to ignore the mirrored contrasts of letters even if this hinders performance. In particular, we hypothesized that this ability would be preserved for the visually presented letters of the Braille alphabet despite their poor fit to the constraints of the human visual system, as it did for congenital Braille readers when they explored the same letters through the tactile modality (de Heering, Collignon, & Kolinsky, 2018). To test so, we measured visual Braille readers' mirror costs, indexing for their difficulty to consider mirrored items as identical compared to strictly identical items, for three materials: Braille letters, geometrical shapes and Latin letters, which invariant properties are typically considered as having been selected through cultural evolution because they match the requirements of the visual system. Contrary to people having never experienced Braille, Braille readers' mirror cost was of the same magnitude for Latin letters and Braille letters and steadily increased the more they had experience with the latter material. Both these costs were also stronger than what was observed for geometrical shapes. Overall these results suggest that the poor adequacy of the Braille alphabet to the visual system does not impede Braille readers to break mirror invariance for the Braille material.

Orthographic processing is a key predictor of reading fluency in good and poor readers in a transparent orthography

We used structural equation modeling to investigate sources of individual differences in oral reading fluency in a transparent orthography, Russian. Phonological processing, orthographic processing, and rapid automatized naming were used as independent variables, each derived from a combination of two scores: phonological awareness and pseudoword repetition, spelling and orthographic choice, and rapid serial naming of letters and digits, respectively. The contribution of these to oral text-reading fluency was evaluated as a direct relationship and via two mediators, decoding accuracy and unitized reading, measured with a single-word oral reading test. The participants were "good" and "poor" readers, i.e., those with reading skills above the 90^th and below the 10^th percentiles (n = 1,344, grades 2-6, St. Petersburg, Russia). In both groups, orthographic processing skills significantly contributed to fluency and unitized reading, but not to decoding accuracy. Phonological processing skills did not contribute directly to reading fluency in either group, while contributing to decoding accuracy and, to a lesser extent, to unitized reading. With respect to the roles of decoding accuracy and unitized reading, the results for good and poor readers diverged: in good readers, unitized reading, but not decoding accuracy, was significantly related to reading fluency. For poor readers, decoding accuracy (measured as pseudoword decoding) was related to reading fluency, but unitized reading was not. These results underscore the importance of orthographic skills for reading fluency even in an orthography with consistent phonology-to-orthography correspondences. They also point to a qualitative difference in the reading strategies of good and poor readers.

Word selectivity in high-level visual cortex and reading skill

Word-selective neural responses in human ventral occipito-temporal cortex (VOTC) emerge as children learn to read, creating a visual word form area (VWFA) in the literate brain. It has been suggested that the VWFA arises through competition between pre-existing selectivity for other stimulus categories, changing the topography of VOTC to support rapid word recognition. Here, we hypothesized that competition between words and objects would be resolved as children acquire reading skill. Using functional magnetic resonance imaging (fMRI), we examined the relationship between responses to words and objects in VOTC in two ways. First, we defined the VWFA using a words > objects contrast and found that only skilled readers had a region that responded more to words than objects. Second, we defined the VWFA using a words > faces contrast and examined selectivity for words over objects in this region. We found that word selectivity strongly correlated with reading skill, suggesting reading skill-dependent tuning for words. Furthermore, we found that low word selectivity in struggling readers was not due to a lack of response to words, but to a high response to objects. Our results suggest that the fine-tuning of word-selective responses in VOTC is a critical component of skilled reading.

Converging evidence for functional and structural segregation within the left ventral occipitotemporal cortex in reading

The ventral occipitotemporal cortex (vOTC) is crucial for recognizing visual patterns, and previous evidence suggests that there may be different subregions within the vOTC involved in the rapid identification of word forms. Here, we characterize vOTC reading circuitry using a multimodal approach combining functional, structural, and quantitative MRI and behavioral data. Two main word-responsive vOTC areas emerged: a posterior area involved in visual feature extraction, structurally connected to the intraparietal sulcus via the vertical occipital fasciculus; and an anterior area involved in integrating information with other regions of the language network, structurally connected to the angular gyrus via the posterior arcuate fasciculus. Furthermore, functional activation in these vOTC regions predicted reading behavior outside of the scanner. Differences in the microarchitectonic properties of gray-matter cells in these segregated areas were also observed, in line with earlier cytoarchitectonic evidence. These findings advance our understanding of the vOTC circuitry by linking functional responses to anatomical structure, revealing the pathways of distinct reading-related processes.

Effect of Different Movement Speed Modes on Human Action Observation: An EEG Study

Action observation (AO) generates event-related desynchronization (ERD) suppressions in the human brain by activating partial regions of the human mirror neuron system (hMNS). The activation of the hMNS response to AO remains controversial for several reasons. Therefore, this study investigated the activation of the hMNS response to a speed factor of AO by controlling the movement speed modes of a humanoid robot's arm movements. Since hMNS activation is reflected by ERD suppressions, electroencephalography (EEG) with BCI analysis methods for ERD suppressions were used as the recording and analysis modalities. Six healthy individuals were asked to participate in experiments comprising five different conditions. Four incremental-speed AO tasks and a motor imagery (MI) task involving imaging of the same movement were presented to the individuals. Occipital and sensorimotor regions were selected for BCI analyses. The experimental results showed that hMNS activation was higher in the occipital region but more robust in the sensorimotor region. Since the attended information impacts the activations of the hMNS during AO, the pattern of hMNS activations first rises and subsequently falls to a stable level during incremental-speed modes of AO. The discipline curves suggested that a moderate speed within a decent inter-stimulus interval (ISI) range produced the highest hMNS activations. Since a brain computer/machine interface (BCI) builds a path-way between human and computer/mahcine, the discipline curves will help to construct BCIs made by patterns of action observation (AO-BCI). Furthermore, a new method for constructing non-invasive brain machine brain interfaces (BMBIs) with moderate AO-BCI and motor imagery BCI (MI-BCI) was inspired by this paper.

Supramodal agnosia for oblique mirror orientation in patients with periventricular leukomalacia

Periventricular leukomalacia (PVL) is characterized by focal necrosis at the level of the periventricular white matter, often observed in preterm infants. PVL is frequently associated with motor impairment and with visual deficits affecting primary stages of visual processes as well as higher visual cognitive abilities. Here we describe six PVL subjects, with normal verbal IQ, showing orientation perception deficits in both the haptic and visual domains. Subjects were asked to compare the orientation of two stimuli presented simultaneously or sequentially, using both a two alternative forced choice (2AFC) orientation-discrimination and a matching procedure. Visual stimuli were oriented gratings or bars or collinear short lines embedded within a random pattern. Haptic stimuli comprised two rotatable wooden sticks. PVL patients performed at chance in discriminating the oblique orientation, both for visual and haptic stimuli. Moreover when asked to reproduce the oblique orientation, they often oriented the stimulus along the symmetric mirror orientation. The deficit generalized to stimuli varying in many low level features, was invariant for spatiotopic object orientation, and also occurred for sequential presentations. The deficit was specific to oblique orientations, and not for horizontal or vertical stimuli. These findings show that PVL can affect a specific network involved with the supramodal perception of mirror symmetry orientation.

The emergence of the visual word form: Longitudinal evolution of category-specific ventral visual areas during reading acquisition

How does education affect cortical organization? All literate adults possess a region specialized for letter strings, the visual word form area (VWFA), within the mosaic of ventral regions involved in processing other visual categories such as objects, places, faces, or body parts. Therefore, the acquisition of literacy may induce a reorientation of cortical maps towards letters at the expense of other categories such as faces. To test this cortical recycling hypothesis, we studied how the visual cortex of individual children changes during the first months of reading acquisition. Ten 6-year-old children were scanned longitudinally 6 or 7 times with functional magnetic resonance imaging (fMRI) before and throughout the first year of school. Subjects were exposed to a variety of pictures (words, numbers, tools, houses, faces, and bodies) while performing an unrelated target-detection task. Behavioral assessment indicated a sharp rise in grapheme-phoneme knowledge and reading speed in the first trimester of school. Concurrently, voxels specific to written words and digits emerged at the VWFA location. The responses to other categories remained largely stable, although right-hemispheric face-related activity increased in proportion to reading scores. Retrospective examination of the VWFA voxels prior to reading acquisition showed that reading encroaches on voxels that are initially weakly specialized for tools and close to but distinct from those responsive to faces. Remarkably, those voxels appear to keep their initial category selectivity while acquiring an additional and stronger responsivity to words. We propose a revised model of the neuronal recycling process in which new visual categories invade weakly specified cortex while leaving previously stabilized cortical responses unchanged.

Blind readers break mirror invariance as sighted do

Mirror invariance refers to a predisposition of humans, including infants and animals, which urge them to consider mirrored images as corresponding to the same object. Yet in order to learn to read a written system that incorporates mirrored letters (e.g., <b> vs. <d> in the Latin alphabet), humans learn to break this perceptual bias. Here we examined the role visual experience and input modality play in the emergence of this bias. To this end, we tested congenital blind (CB) participants in two same-different tactile comparison tasks including pairs of mirrored and non-mirrored Braille letters as well as embossed unfamiliar geometric shapes and Latin letters, and compared their results to those of age-matched sighted participants involved in similar but visually-presented tasks. Sighted participants showed a classical pattern of results for their material of expertise, Latin letters. CB's results signed for their expertise with the Braille script compared to the other two materials that they processed according to an internal frame of reference. They also evidenced that they automatically break mirror invariance for different materials explored through the tactile modality, including Braille letters. Altogether, these results demonstrate that learning to read Braille through the tactile modality allows breaking mirror invariance in a comparable way to what is observed in sighted individuals for the mirrored letters of the Latin alphabet.

Increasing expertise to a novel script modulates the visual N1 ERP in healthy adults

Neural tuning to print develops when children learn to read and is reflected by a more pronounced left occipito-temporal negativity to orthographic stimuli as compared to non-orthographic false fonts or symbols after around 150–250 ms in their N1, a visual event-related potential (ERP). In adults, initial expertise for a novel script can emerge in less than 2 hours through repeated exposure or training. Here, we aimed to assess changes in the visual N1 related to the process of learning associations between unknown written characters and familiar, spoken syllables or words. Thirty-two healthy literate adults learned to associate a set of foreign characters with either syllables or German words within a single experimental session. EEG was recorded during a visual one-back character repetition detection task in which trained characters, untrained characters and familiar letters were presented before and after the training. A bilateral occipito-temporal increase in the N1 negativity with training was only found for the newly learned characters, but not for the control characters. In conclusion, the present data indicate that expertise to novel characters can be induced by a short character–sound association training and is reflected by a bilateral modulation of the visual N1 amplitude. However, no differentiation was found regarding the comparison of word or syllable training, indicating that the visual N1 most likely reflects gaining expertise driven by phonological associations common to both training types.

How interindividual differences in brain anatomy shape reading accuracy

The capacity to read develops throughout intensive academic learning and training. Several studies have investigated the impact of reading on the brain, and particularly how the anatomy of the brain changes with reading acquisition. In the present study, we investigated the converse issue, namely whether and how reading acquisition is constrained by the anatomy of the brain. Using multimodal MRI, we found that (a) the pattern (continuous or interrupted sulcus) of the posterior part of the left lateral occipito-temporal sulcus (OTS) hosting the visual word form area (VWFA) predicts reading skills in adults; that (b) this effect is modulated by the age of reading acquisition; and that (c) the length of the OTS sulcal interruption is associated with reading skills. Because the sulcal pattern is determined in utero, our findings suggest that individual difference in reading skills can be traced back to early stages of brain development in addition to the well-established socioeconomic and educational factors.

The Minimal and Short-Lived Effects of Minority Language Exposure on the Executive Functions of Frisian-Dutch Bilingual Children

Various studies have shown that bilingual children need a certain degree of proficiency in both languages before their bilingual experiences enhance their executive functioning (EF). In the current study, we investigated if degree of bilingualism in Frisian-Dutch children influenced EF and if this effect was sustained over a 3-year period. To this end, longitudinal data were analyzed from 120 Frisian-Dutch bilingual children who were 5- or 6-years-old at the first time of testing. EF was measured with two attention and two working memory tasks. Degree of bilingualism was defined as language balance based on receptive vocabulary and expressive morphology scores in both languages. In a context with a minority and a majority language, such as the Frisian-Dutch context, chances for becoming proficient in both languages are best for children who speak the minority language at home. Therefore, in a subsequent analysis, we examined whether minority language exposure predicted language balance and whether there was a relationship between minority language exposure and EF, mediated by language balance. The results showed that intensity of exposure to Frisian at home, mediated by language balance, had an impact on one of the attention tasks only. It predicted performance on this task at time 1, but not at time 2 and 3. This partially confirms previous evidence that the cognitive effects of bilingualism are moderated by degree of bilingualism and furthermore reveals that substantial minority language exposure at home indirectly affects bilingual children's cognitive development, namely through mediation with degree of bilingualism. However, the findings also demonstrate that the effect of bilingualism on EF is limited and unstable.

Word-related N170 responses to implicit and explicit reading tasks in neoliterate adults

The present study addresses word recognition automaticity in Spanish-speaking adults who are neoliterate by assessing the event-related potential N170 for word stimuli. Participants engaged in two reading conditions that vary the degree of attention required for linguistic components of reading: (a) an implicit reading task, in which they detected immediate repetitions of words and symbols (one-back paradigm); (b) an explicit reading task, in which they determined if pairs of visual-auditory words matched (reading verification task). Results were compared to those of a group of people who learned to read in childhood. N170 amplitudes on left and right occipito-temporal regions were registered for each condition. A left-lateralization of N170 for word stimuli was considered as an index of word reading automaticity. No left-lateralized N170 was found for the neoliterate group in either condition. In addition, N170 amplitude for words was larger on the right than the left occipito-temporal region for the reading verification task. Participants from the comparison group showed left-lateralized N170 amplitude for words in both conditions. Findings suggest that the neoliterate group investigated here had not yet acquired automaticity of word recognition, but could be showing evidence of word familiarization.

Attentional selection predicts rapid automatized naming ability in Chinese-speaking children with ADHD

Children with attention-deficit/hyperactivity disorder (ADHD) are reported to have a significantly higher risk of showing reading difficulties or disorders. Here, we aimed to identify the relationship between electroencephalographic (EEG) marker of spatial attention and reading ability in Chinese children with ADHD. First, we demonstrated that rapid automatized naming (RAN) is a strong predictor of reading ability in Chinese-speaking children. Then, EEG data of 9-to 15-year-old children with ADHD (n = 38) and typically developing (TD) controls (n = 36) were collected while the children performed a classical visual search task. Children with ADHD showed slower RAN speed than TD children. For event-related potentials (ERPs), children with ADHD showed a reduced target-evoked N2pc component, which predicted their poorer RAN performance. However, in TD children the early occipital P1 amplitude was negatively correlated with their RAN performance. The correlation between decreased N2pc and poor RAN performance in children with ADHD suggests that their reading problems may in part be due to impaired attentional selection. In contrast, in TD children, development in early visual processing co-occurs with improvements in reading ability.