Evaluation of the dual route theory of reading: a metanalysis of 35 neuroimaging studies

Co-registration of eye movements and neuroimaging for studying contextual predictions in natural reading

Sixteen years ago, Sereno and Rayner (2003. Measuring word recognition in reading: eye movements and event-related potentials. Trends in Cognitive Sciences, 7(11), 489-493) illustrated how "by means of review and comparison" eye movement (EM) and event-related potential (ERP) studies may advance our understanding of visual word recognition. Attempts to simultaneously record EMs and ERPs soon followed. Recently, this co-registration approach has also been transferred to fMRI and oscillatory EEG. With experimental settings close to natural reading, co-registration enables us to directly integrate insights from EM and neuroimaging studies. This should extend current experimental paradigms by moving the field towards studying sentence-level processing including effects of context and parafoveal preview. This article will introduce the basic principles and applications of co-registration and selectively review how this approach may shed light on one of the most controversially discussed issues in reading research, contextual predictions in online language processing.

Localization of Phonological and Semantic Contributions to Reading

Reading involves the rapid extraction of sound and meaning from print through a cooperative division of labor between phonological and lexical-semantic processes. Whereas lesion studies of patients with stereotyped acquired reading deficits contributed to the notion of a dissociation between phonological and lexical-semantic reading, the neuroanatomical basis for effects of lexicality (word vs pseudoword), orthographic regularity (regular vs irregular spelling-sound correspondences), and concreteness (concrete vs abstract meaning) on reading is underspecified, particularly outside the context of strong behavioral dissociations. Support vector regression lesion-symptom mapping (LSM) of 73 left hemisphere stroke survivors (male and female human subjects) not preselected for stereotyped dissociations revealed the differential contributions of specific cortical regions to reading pseudowords (ventral precentral gyrus), regular words (planum temporale, supramarginal gyrus, ventral precentral and postcentral gyrus, and insula), and concrete words (pars orbitalis and pars triangularis). Consistent with the primary systems view of reading being parasitic on language-general circuitry, our multivariate LSM analyses revealed that phonological decoding depends on perisylvian areas subserving sound-motor integration and that semantic effects on reading depend on frontal cortex subserving control over concrete semantic representations that aid phonological access from print. As the first study to localize the differential cortical contributions to reading pseudowords, regular words, and concrete words in stroke survivors with variable reading abilities, our results provide important information on the neurobiological basis of reading and highlight the insights attainable through multivariate, process-based approaches to alexia.SIGNIFICANCE STATEMENT Whereas fMRI evidence for neuroanatomical dissociations between phonological and lexical-semantic reading is abundant, evidence from modern lesion studies establishing the differential contributions of specific brain regions to specific reading processes is lacking. Our application of multivariate lesion-symptom mapping revealed that effects of lexicality, orthographic regularity, and concreteness on reading differentially depend on areas subserving auditory-motor integration and semantic control. Phonological decoding of print relies on a dorsal perisylvian network supporting auditory and articulatory representations, with unfamiliar words relying especially on articulatory mapping. In tandem with this dorsal decoding system, anterior inferior frontal gyrus may coordinate control over concrete semantic representations that support mapping of print to sound, which is a novel potential mechanism for semantic influences on reading.

Steady state visual evoked potentials in reading aloud: Effects of lexicality, frequency and orthographic familiarity

The present study explored the possibility to use Steady-State Visual Evoked Potentials (SSVEPs) as a tool to investigate the core mechanisms in visual word recognition. In particular, we investigated three benchmark effects of reading aloud: lexicality (words vs. pseudowords), frequency (high-frequency vs. low-frequency words), and orthographic familiarity ('familiar' versus 'unfamiliar' pseudowords). We found that words and pseudowords elicited robust SSVEPs. Words showed larger SSVEPs than pseudowords and high-frequency words showed larger SSVEPs than low-frequency words. SSVEPs were not sensitive to orthographic familiarity. We further localized the neural generators of the SSVEP effects. The lexicality effect was located in areas associated with early level of visual processing, i.e. in the right occipital lobe and in the right precuneus. Pseudowords produced more activation than words in left sensorimotor areas, rolandic operculum, insula, supramarginal gyrus and in the right temporal gyrus. These areas are devoted to speech processing and/or spelling-to-sound conversion. The frequency effect involved the left temporal pole and orbitofrontal cortex, areas previously implicated in semantic processing and stimulus-response associations respectively, and the right postcentral and parietal inferior gyri, possibly indicating the involvement of the right attentional network.

High-level Integrative Networks: A Resting-state fMRI Investigation of Reading and Spelling

Orthographic processing skills (reading and spelling) are evolutionarily recent and mastered late in development, providing an opportunity to investigate how the properties of the neural networks supporting skills of this type compare to those supporting evolutionarily older, well-established "reference" networks. Although there has been extensive research using task-based fMRI to study the neural substrates of reading, there has been very little using resting-state fMRI to examine the properties of orthographic networks. In this investigation using resting-state fMRI, we compare the within-network and across-network coherence properties of reading and spelling networks directly to these properties of reference networks, and we also compare the network properties of the key node of the orthographic networks-the visual word form area-to those of the other nodes of the orthographic and reference networks. Consistent with previous results, we find that orthographic processing networks do not exhibit certain basic network coherence properties displayed by other networks. However, we identify novel distinctive properties of the orthographic processing networks and establish that the visual word form area has unusually high levels of connectivity with a broad range of brain areas. These characteristics form the basis of our proposal that orthographic networks represent a class of "high-level integrative networks" with distinctive properties that allow them to recruit and integrate multiple, lower level processes.

An fMRI-adaptation study of phonological and orthographic selectivity to written words in adults with poor reading skills

Typical readers rely on two brain pathways for word processing in the left hemisphere: temporo-parietal cortex (TPC) and inferior frontal cortex (IFC), thought to subserve phonological decoding, and occipito-temporal cortex (OTC), including the "visual word form area" (VWFA), thought to subserve orthographic processing. How these regions are affected in developmental dyslexia has been a topic of intense research. We employed fMRI rapid adaptation (fMRI-RA) in adults with low reading skills to examine in independently-defined functional regions of interest (ROIs) phonological selectivity to written words in left TPC and IFC, and to orthographic selectivity to written words in OTC. Consistent with the phonological deficit hypothesis of dyslexia, we found responsivity but not selectivity to phonology, as accessed by written words, in the posterior superior temporal gyrus (pSTG) of the TPC. On the other hand, we found orthographic selectivity in the VWFA of the OTC. We also found selectivity to orthographic and not phonological processing in the IFG, a finding previously reported for typical readers. Together our results demonstrate that in adults with poor reading skills, selectivity to phonology is compromised in pSTG, while selectivity to orthography in the VWFA remains unaffected at this level of processing.

Connectivity between the visual word form area and the parietal lobe improves after the first year of reading instruction: a longitudinal MRI study in children

Shortly after reading instruction, a region in the ventral occipital temporal cortex (vOTC) of the left hemisphere, the Visual Word Form Area (VWFA), becomes specialized for written words. Its reproducible location across scripts suggests important anatomical constraints, such as specific patterns of connectivity, notably to spoken language areas. Here, we explored the structural connectivity of the emerging VWFA in terms of its specificity relative to other ventral visual regions and its stability throughout the process of reading instruction in ten children studied longitudinally over 2 years. Category-specific regions for words, houses, faces, and tools were identified in the left vOTC of each subject with functional MRI. With diffusion MRI and tractography, we reconstructed the connections of these regions at two time points (mean age ± standard deviation: 6.2 ± 0.3, 7.2 ± 0.4 years). We first showed that the regions for each visual category harbor their own specific connectivity, all of which precede reading instruction and remain stable throughout development. The most specific connections of the VWFA were to the dorsal posterior parietal cortex. We then showed that microstructural changes in these connections correlated with improvements in reading scores over the first year of instruction but not 1 year later in a subsample of eight children (age: 8.4 ± 0.3 years). These results suggest that the VWFA location depends on its connectivity to distant regions, in particular, the left inferior parietal region which may play a crucial role in visual field maps and eye movement dynamics in addition to attentional control in letter-by-letter reading and disambiguation of mirror-letters during the first stages of learning to read.

White matter network connectivity deficits in developmental dyslexia

A number of studies have shown an abnormal connectivity of certain white matter pathways in developmental dyslexia, as well as correlations between these white matter pathways and behavioral deficits. However, whether developmental dyslexia presents broader white matter network connectivity disruption is currently unknown. The present study reconstructed white matter networks for 26 dyslexic children (11.61 ± 1.31 years) and 31 age-matched controls (11.49 ± 1.36 years) using constrained spherical deconvolution tractography. Network-based statistics (NBS) analysis was performed to identify network connectivity deficits in dyslexic individuals. Network topological features were measured based on graph theory to examine whether these parameters correlate with literacy skills, and whether they explain additional variance over previously established white matter connectivity abnormalities in dyslexic children. The NBS analysis identified a network connecting the left-occipital-temporal cortex and temporo-parietal cortex that had decreased streamlines in dyslexic children. Four network topological parameters (clustering coefficient, local efficiency, transitivity, and global efficiency) were positively correlated with literacy skills of dyslexic children, and explained a substantial proportion of additional variance in literacy skills beyond connectivity measures of white matter pathways. This study for the first time reports a disconnection in a local subnetwork in the left hemisphere in dyslexia and shows that the global white matter network topological properties contribute to reduced literacy skills in dyslexic children.

Neural substrates of word category information as the basis of syntactic processing

The ability to use word category information (WCI) for syntactic structure building has been hypothesized to be the essence of human language faculty. The neural substrate of the ability of using the WCI for the complex syntactic hierarchical structure processing, however, is yet unknown. Therefore, we directly conducted an fMRI experiment by using a pseudo-Chinese artificial language with syntactic structures containing a center-embedded relative clause. Thirty non-Chinese native (Korean) speakers were randomly divided into two groups: one acquired WCI and WCI-based syntactic rules (the WCI group) before the scanning session, and the other did not (the non-WCI group). Both groups were required to judge the grammaticality of the testing sentences, with critical long-distance dependencies between two elements (the main verb and the relativizer). Behaviorally, the WCI group's accuracy was significantly higher and its reaction time was shorter. The scanning results showed that the left superior temporal gyrus (STG) and Broca's area were more strongly activated for the WCI group, and the dynamic causal modeling analyses revealed a distinct effective connectivity pattern for this group. Therefore, the present research, for the first time, reveals that the activation of and the functional connectivity between Broca's area and the left STG play a critical role in the ability of the rule-based use of the WCI which is crucial for complex hierarchical structure building, and might be substantially corresponding to the "labeling competence" within the linguistic framework.

Adaptive paradigms for mapping phonological regions in individual participants

Phonological encoding depends on left-lateralized regions in the supramarginal gyrus and the ventral precentral gyrus. Localization of these phonological regions in individual participants-including individuals with language impairments-is important in several research and clinical contexts. To localize these regions, we developed two paradigms that load on phonological encoding: a rhyme judgment task and a syllable counting task. Both paradigms relied on an adaptive staircase design to ensure that each individual performed each task at a similarly challenging level. The goal of this study was to assess the validity and reliability of the two paradigms, in terms of their ability to consistently produce left-lateralized activations of the supramarginal gyrus and ventral precentral gyrus in neurologically normal individuals with presumptively normal language localization. Sixteen participants were scanned with fMRI as they performed the rhyme judgment paradigm, the syllable counting paradigm, and an adaptive semantic paradigm that we have described previously. We found that the rhyme and syllable paradigms both yielded left-lateralized supramarginal and ventral precentral activations in the majority of participants. The rhyme paradigm produced more lateralized and more reliable activations, and so should be favored in future applications. In contrast, the semantic paradigm did not reveal supramarginal or precentral activations in most participants, suggesting that the recruitment of these regions is indeed driven by phonological encoding, not language processing in general. In sum, the adaptive rhyme judgment paradigm was effective in localizing left-lateralized phonological encoding regions in individual participants, and, in conjunction with the adaptive semantic paradigm, can be used to map individual language networks.

Cross-linguistic transfer in bilinguals reading in two alphabetic orthographies: The grain size accommodation hypothesis

Reading acquisition is one of the most complex and demanding learning processes faced by children in their first years of schooling. If reading acquisition is challenging in one language, how is it when reading is acquired simultaneously in two languages? What is the impact of bilingualism on the development of literacy? We review behavioral and neuroimaging evidence from alphabetic writing systems suggesting that early bilingualism modulates reading development. Particularly, we show that cross-linguistic variations and cross-linguistic transfer affect bilingual reading strategies as well as their cognitive underpinnings. We stress the fact that the impact of bilingualism on literacy acquisition depends on the specific combination of languages learned and does not manifest itself similarly across bilingual populations. We argue that these differences can be explained by variations due to orthographic depth in the grain sizes used to perform reading and reading-related tasks. Overall, we propose novel hypotheses to shed light on the behavioral and neural variability observed in reading skills among bilinguals.

Brain networks' functional connectivity separates aphasic deficits in stroke

OBJECTIVE

To investigate whether different language deficits are distinguished by the relative strengths of their association with the functional connectivity (FC) at rest of the language network (LN) and cingulo-opercular network (CON) after aphasic stroke.

METHODS

In a group of patients with acute stroke and left-hemisphere damage, we identified 3 distinct, yet correlated, clusters of deficits including comprehension/lexical semantic, grapheme-phoneme knowledge, and verbal executive functions. We computed partial correlations in which the contributions of a behavioral cluster and network FC of no interest were statistically regressed out.

RESULTS

We observed a double dissociation such that impairment of grapheme-phoneme knowledge was more associated with lower FC of the LN within the left hemisphere than lower FC of the CON, whereas verbal executive deficits were more related to lower FC of the CON than the LN in the left hemisphere. Furthermore, the specific association between language deficits and FC was independent of the amount of structural damage to the LN and CON.

CONCLUSION

These findings indicate that after a left-hemisphere lesion, the type of language impairment is related to the abnormal pattern of correlated activity in different networks. Accordingly, they extend the concept of a neuropsychological double dissociation from structural damage to functional network abnormalities. Finally, current results strongly argue in favor of the behavioral specificity of intrinsic brain activity after focal structural damage.

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.

Common variation within the SETBP1 gene is associated with reading-related skills and patterns of functional neural activation

Epidemiological population studies highlight the presence of substantial individual variability in reading skill, with approximately 5-10% of individuals characterized as having specific reading disability (SRD). Despite reported substantial heritability, typical for a complex trait, the specifics of the connections between reading and the genome are not understood. Recently, the SETBP1 gene has been implicated in several complex neurodevelopmental syndromes and disorders that impact language. Here, we examined the relationship between common polymorphisms in this gene, reading, and reading associated behaviors using data from an ongoing project on the genetic basis of SRD (n = 135). In addition, an exploratory analysis was conducted to examine the relationship between SETBP1 and brain activation using functional magnetic resonance imaging (fMRI; n = 73). Gene-based analyses revealed a significant association between SETBP1 and phonological working memory, with rs7230525 as the strongest associated single nucleotide polymorphism (SNP). fMRI analysis revealed that the rs7230525-T allele is associated with functional neural activation during reading and listening to words and pseudowords in the right inferior parietal lobule (IPL). These findings suggest that common genetic variation within SETBP1 is associated with reading behavior and reading-related brain activation patterns in the general population.

The Experience of Beauty of Chinese Poetry and Its Neural Substrates

Chinese poetry has a long history and high esthetic value. People who engage esthetically with Chinese poetry would feel the sense of beauty naturally. However, there is little information regarding what happens in the brain when an individual appreciates Chinese poetry, and how the brain processes the subject’s appreciation of beauty. Herein, we used functional magnetic resonance imaging (fMRI) to investigate the neural substrates of experiencing beauty by appreciating Chinese poetry. The participants in our study were 28 college students and the stimuli consisted of 25 Chinese poetry and 25 prose selections. Based on an event-related paradigm, the findings of this study suggested that different areas scattered in both the left and right cerebral hemispheres are activated when an individual appreciates Chinese poetry. Compared to reading prose, appreciating Chinese poetry heightens the activation of the left inferior orbitofrontal cortex (OFC), the bilateral insula, the left fusiform, the left supplementary motor area (SMA), and the left precentral gyrus. In these areas, the left inferior OFC and the bilateral insula are considered closely related to experiencing beauty of Chinese poetry, which have been demonstrated that it is an important neural basis of esthetic beauty when using other types of materials. The findings of this study shed new light on the complex but ordinary processes of experiencing beauty when appreciating Chinese poetry and show that some key processes underlying the feeling of esthetic beauty are shared across different esthetic domains.

Atypical Structural Asymmetry of the Planum Temporale is Related to Family History of Dyslexia

Research on the neural correlates of developmental dyslexia indicates atypical anatomical lateralization of the planum temporale, a higher-order cortical auditory region. Yet whether this atypical lateralization precedes reading acquisition and is related to a familial risk for dyslexia is not currently known. In this study, we address these questions in 2 separate cohorts of young children and adolescents with and without a familial risk for dyslexia. Planum temporale surface area was manually labeled bilaterally, on the T1-weighted MR brain images of 54 pre-readers (mean age: 6.2 years, SD: 3.2 months; 33 males) and 28 adolescents (mean age: 14.7 years, SD: 3.3 months; 11 males). Half of the pre-readers and adolescents had a familial risk for dyslexia. In both pre-readers and adolescents, group comparisons of left and right planum temporale surface area showed a significant interaction between hemisphere and family history of dyslexia, with participants who had no family risk for dyslexia showing greater leftward asymmetry of the planum temporale. This effect was confirmed when analyses were restricted to normal reading participants. Altered planum temporale asymmetry thus seems to be related to family history of dyslexia.

Neural organization of ventral white matter tracts parallels the initial steps of reading development: A DTI tractography study

Insight in the developmental trajectory of the neuroanatomical reading correlates is important to understand related cognitive processes and disorders. In adults, a dual pathway model has been suggested encompassing a dorsal phonological and a ventral orthographic white matter system. This dichotomy seems not present in pre-readers, and the specific role of ventral white matter in reading remains unclear. Therefore, the present longitudinal study investigated the relation between ventral white matter and cognitive processes underlying reading in children with a broad range of reading skills (n = 61). Ventral pathways of the reading network were manually traced using diffusion tractography: the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF). Pathways were examined pre-reading (5-6 years) and after two years of reading acquisition (7-8 years). Dimension reduction for the cognitive measures resulted in one component for pre-reading cognitive measures and a separate phonological and orthographic component for the early reading measures. Regression analyses revealed a relation between the pre-reading cognitive component and bilateral IFOF and left ILF. Interestingly, exclusively the left IFOF was related to the orthographic component, whereas none of the pathways was related to the phonological component. Hence, the left IFOF seems to serve as the lexical reading route, already in the earliest reading stages.

Effect of reading intervention and task difficulty on orthographic and phonological reading systems in the brain

Children with poor reading skills have differences in brain function when compared to typically-developing readers, and there may also be changes in the brain following reading intervention. However, most functional imaging studies focus on phonological reading tasks with one level of task difficulty. The purpose of this study was to compare good and poor readers on functional magnetic resonance imaging (fMRI) tasks of orthography (spelling) and phonology (rhyming) before and after 3 months of school-based intervention. These tasks were also modulated by task difficulty based on printed word frequency. The results showed that primarily left hemisphere regions were activated for the spelling and rhyming tasks, and poor readers showed a pattern of increased activation in bilateral inferior frontal, bilateral insula, right parietal, and left cerebellum following intervention. Activity in left pars triangularis and right parietal regions were associated with gains in decoding skills. Intervention effects appeared across blocks of easy and difficult words, except for the right parietal cortex. In this region, poor readers had greater activity on the easy word blocks after intervention, which indicates that there was increased recruitment of the right parietal cortex for relatively easy words. These results indicate that effects of intervention may be more evident on phonological tasks in comparison to orthographic tasks, and some of these effects may be modulated by relative task difficulty.

Atypical White Matter Connectivity in Dyslexic Readers of a Fairly Transparent Orthography

Atypical structural properties of the brain's white matter bundles have been associated with failing reading acquisition in developmental dyslexia. Because these white matter properties may show dynamic changes with age and orthographic depth, we examined fractional anisotropy (FA) along 16 white matter tracts in 8- to 11-year-old dyslexic (DR) and typically reading (TR) children learning to read in a fairly transparent orthography (Dutch). Our results showed higher FA values in the bilateral anterior thalamic radiations of DRs and FA values of the left thalamic radiation scaled with behavioral reading-related scores. Furthermore, DRs tended to have atypical FA values in the bilateral arcuate fasciculi. Children's age additionally predicted FA values along the tracts. Together, our findings suggest differential contributions of cortical and thalamo-cortical pathways to the developing reading network in dyslexic and typical readers, possibly indicating prolonged letter-by-letter reading or increased attentional and/or working memory demands in dyslexic children during reading.

Functional Dynamics of Dorsal and Ventral Reading Networks in Bilinguals

In today's world, bilingualism is increasingly common. However, it is still unclear how left-lateralized dorsal and ventral reading networks are tuned to reading in proficient second-language learners. Here, we investigated differences in functional regional activation and connectivity as a function of L1 and L2 reading, L2 orthographic depth, and task demands. Thirty-seven late bilinguals with the same L1 and either an opaque or transparent L2 performed perceptual and semantic reading tasks in L1 and L2 during functional magnetic resonance imaging (fMRI) scanning. Results revealed stronger regional recruitment for L2 versus L1 reading and stronger connectivity within the dorsal stream during L1 versus L2 reading. Differences in orthographic depth were associated with a segregated profile of left ventral occipitotemporal (vOT) coactivation with dorsal regions for the transparent L2 group and with ventral regions for the opaque L2 group. Finally, semantic versus perceptual demands modulated left vOT engagement, supporting the interactive account of the contribution of vOT to reading, and were associated with stronger coactivation within the ventral network. Our findings support a division of labor between ventral and dorsal reading networks, elucidating the critical role of the language used to read, L2 orthographic depth, and task demands on the functional dynamics of bilingual reading.

Dorsal and ventral visual stream contributions to preserved reading ability in patients with central alexia

We investigated the role of the left temporo-parietal regions in supporting reading abilities of 23 patients with central alexia (CA). For the behavioural data, we employed principal components analysis (PCA), which identified two components: 'reading aloud' and 'reading for meaning'. Voxel-based morphometry of the PCA results showed an association between reading aloud and grey matter density in the left supramarginal gyrus, part of the dorsal visual stream. By contrast, reading for meaning was associated with a large cluster in the left ventral visual stream, from the collateral sulcus to the anterior temporal pole. Most of the peaks were within the group lesion map, indicating that sparing of these areas results in better preservation of reading ability. However, one white matter (WM) cluster in the medial occipitotemporal lobe was outside the lesioned area. A post-hoc test demonstrated that WM density here was equivalent to controls, suggesting that this was not driven by lesion effects. The two likeliest explanations for this correlation are: 1) that pre-morbid, inter-individual differences in brain structure mitigate the effects of CA; 2) that post-morbid practice-based with reading caused compensatory plasticity. We hope to adjudicate between these explanations with longitudinal therapy data collected in this cohort.

Current perspectives on the cerebellum and reading development

The dominant neural models of typical and atypical reading focus on the cerebral cortex. However, Nicolson et al. (2001) proposed a model, the cerebellar deficit hypothesis, in which the cerebellum plays an important role in reading. To evaluate the evidence in support of this model, we qualitatively review the current literature and employ meta-analytic tools examining patterns of functional connectivity between the cerebellum and the cerebral reading network. We find evidence for a phonological circuit with connectivity between the cerebellum and a dorsal fronto-parietal pathway, and a semantic circuit with cerebellar connectivity to a ventral fronto-temporal pathway. Furthermore, both cerebral pathways have functional connections with the mid-fusiform gyrus, a region implicated in orthographic processing. Consideration of these circuits within the context of the current literature suggests the cerebellum is positioned to influence both phonological and word-based decoding procedures for recognizing unfamiliar printed words. Overall, multiple lines of research provide support for the cerebellar deficit hypothesis, while also highlighting the need for further research to test mechanistic hypotheses.

Large-scale functional networks connect differently for processing words and symbol strings

Reconfigurations of synchronized large-scale networks are thought to be central neural mechanisms that support cognition and behavior in the human brain. Magnetoencephalography (MEG) recordings together with recent advances in network analysis now allow for sub-second snapshots of such networks. In the present study, we compared frequency-resolved functional connectivity patterns underlying reading of single words and visual recognition of symbol strings. Word reading emphasized coherence in a left-lateralized network with nodes in classical perisylvian language regions, whereas symbol processing recruited a bilateral network, including connections between frontal and parietal regions previously associated with spatial attention and visual working memory. Our results illustrate the flexible nature of functional networks, whereby processing of different form categories, written words vs. symbol strings, leads to the formation of large-scale functional networks that operate at distinct oscillatory frequencies and incorporate task-relevant regions. These results suggest that category-specific processing should be viewed not so much as a local process but as a distributed neural process implemented in signature networks. For words, increased coherence was detected particularly in the alpha (8-13 Hz) and high gamma (60-90 Hz) frequency bands, whereas increased coherence for symbol strings was observed in the high beta (21-29 Hz) and low gamma (30-45 Hz) frequency range. These findings attest to the role of coherence in specific frequency bands as a general mechanism for integrating stimulus-dependent information across brain regions.

Individualized Prediction of Reading Comprehension Ability Using Gray Matter Volume

Reading comprehension is a crucial reading skill for learning and putatively contains 2 key components: reading decoding and linguistic comprehension. Current understanding of the neural mechanism underlying these reading comprehension components is lacking, and whether and how neuroanatomical features can be used to predict these 2 skills remain largely unexplored. In the present study, we analyzed a large sample from the Human Connectome Project (HCP) dataset and successfully built multivariate predictive models for these 2 skills using whole-brain gray matter volume features. The results showed that these models effectively captured individual differences in these 2 skills and were able to significantly predict these components of reading comprehension for unseen individuals. The strict cross-validation using the HCP cohort and another independent cohort of children demonstrated the model generalizability. The identified gray matter regions contributing to the skill prediction consisted of a wide range of regions covering the putative reading, cerebellum, and subcortical systems. Interestingly, there were gender differences in the predictive models, with the female-specific model overestimating the males' abilities. Moreover, the identified contributing gray matter regions for the female-specific and male-specific models exhibited considerable differences, supporting a gender-dependent neuroanatomical substrate for reading comprehension.

Alterations in white matter pathways underlying phonological and morphological processing in Chinese developmental dyslexia

Chinese is a logographic language that is different from alphabetic languages in visual and semantic complexity. Thus far, it is still unclear whether Chinese children with dyslexia show similar disruption of white matter pathways as in alphabetic languages. The present study focused on the alteration of white matter pathways in Chinese children with dyslexia. Using diffusion tensor imaging tractography, the bilateral arcuate fasciculus (AF-anterior, AF-posterior and AF-direct segments), inferior fronto-occipital fasciculus (IFOF) and inferior longitudinal fasciculus (ILF) were delineated in each individual’s native space. Compared with age-matched controls, Chinese children with dyslexia showed reduced fractional anisotropy in the left AF-direct and the left ILF. Further regression analyses revealed a functional dissociation between the left AF-direct and the left ILF. The AF-direct tract integrity was associated with phonological processing skill, an ability important for reading in all writing systems, while the ILF integrity was associated with morphological processing skill, an ability more strongly recruited for Chinese reading. In conclusion, the double disruption locus in Chinese children with dyslexia, and the functional dissociation between dorsal and ventral pathways reflect both universal and specific properties of reading in Chinese.

Where arithmetic and phonology meet: The meta-analytic convergence of arithmetic and phonological processing in the brain

Arithmetic facts can be solved using different strategies. Research suggests that some arithmetic problems, particularly those solved by fact retrieval, are related to phonological processing ability and elicit activity in left-lateralized brain regions that support phonological processing. However, it is unclear whether common brain regions support both retrieval-based arithmetic and phonological processing, and if these regions differ across children and adults. This study used activation likelihood estimation to investigate functional neural overlap between arithmetic and phonological processing, separately for children and adults. The meta-analyses in children showed six clusters of overlapping activation concentrated in bilateral frontal regions and in the left fusiform gyrus. The meta-analyses in adults yielded two clusters of concordant activity, one in the left inferior frontal gyrus and one in the left inferior parietal lobule. A qualitative comparison across the two age groups suggests that children show more bilateral and diffuse activation than adults, which may reflect attentional processes that support more effortful processing in children. The present meta-analyses contribute novel insights into the relationship between retrieval-based arithmetic and phonological processing in the brain across children and adults, and brain regions that may support processing of more complex symbolic representations, such as arithmetic facts and words.

Voxel-based lesion analysis of brain regions underlying reading and writing

The neural basis of reading and writing has been a source of inquiry as well as controversy in the neuroscience literature. Reading has been associated with both left posterior ventral temporal zones (termed the "visual word form area") as well as more dorsal zones, primarily in left parietal cortex. Writing has also been associated with left parietal cortex, as well as left sensorimotor cortex and prefrontal regions. Typically, the neural basis of reading and writing are examined in separate studies and/or rely on single case studies exhibiting specific deficits. Functional neuroimaging studies of reading and writing typically identify a large number of activated regions but do not necessarily identify the core, critical hubs. Last, due to constraints on the functional imaging environment, many previous studies have been limited to measuring the brain activity associated with single-word reading and writing, rather than sentence-level processing. In the current study, the brain correlates of reading and writing at both the single- and sentence-level were studied in a large sample of 111 individuals with a history of chronic stroke using voxel-based lesion symptom mapping (VLSM). VLSM provides a whole-brain, voxel-by-voxel statistical analysis of the role of distinct regions in a particular behavior by comparing performance of individuals with and without a lesion at every voxel. Rather than comparing individual cases or small groups with particular behavioral dissociations in reading and writing, VLSM allowed us to analyze data from a large, well-characterized sample of stroke patients exhibiting a wide range of reading and writing impairments. The VLSM analyses revealed that reading was associated with a critical left inferior temporo-occipital focus, while writing was primarily associated with the left supramarginal gyrus. Separate VLSM analyses of single-word versus sentence-level reading showed that sentence-level reading was uniquely associated with anterior to mid-portions of the middle and superior temporal gyri. Both single-word and sentence-level writing overlapped to a great extent in the left supramarginal gyrus, but sentence-level writing was associated with additional underlying white matter pathways such as the internal capsule. These findings suggest that critical aspects of reading and writing processes diverge, with reading relying critically on the ventral visual recognition stream and writing relying on a dorsal visuo-spatial-motor stream.

Early development of letter specialization in left fusiform is associated with better word reading and smaller fusiform face area

A functional region of left fusiform gyrus termed "the visual word form area" (VWFA) develops during reading acquisition to respond more strongly to printed words than to other visual stimuli. Here, we examined responses to letters among 5- and 6-year-old early kindergarten children (N = 48) with little or no school-based reading instruction who varied in their reading ability. We used functional magnetic resonance imaging (fMRI) to measure responses to individual letters, false fonts, and faces in left and right fusiform gyri. We then evaluated whether signal change and size (spatial extent) of letter-sensitive cortex (greater activation for letters versus faces) and letter-specific cortex (greater activation for letters versus false fonts) in these regions related to (a) standardized measures of word-reading ability and (b) signal change and size of face-sensitive cortex (fusiform face area or FFA; greater activation for faces versus letters). Greater letter specificity, but not letter sensitivity, in left fusiform gyrus correlated positively with word reading scores. Across children, in the left fusiform gyrus, greater size of letter-sensitive cortex correlated with lesser size of FFA. These findings are the first to suggest that in beginning readers, development of letter responsivity in left fusiform cortex is associated with both better reading ability and also a reduction of the size of left FFA that may result in right-hemisphere dominance for face perception.

No evidence for systematic white matter correlates of dyslexia and dyscalculia

Learning disabilities such as dyslexia, dyscalculia and their comorbid manifestation are prevalent, affecting as much as 15% of the population. Structural neuroimaging studies have indicated that these disorders can be related to differences in white matter integrity, although findings remain disparate. In this study, we used a unique design composed of individuals with dyslexia, dyscalculia, both disorders and controls, to systematically explore differences in fractional anisotropy across groups using diffusion tensor imaging. Specifically, we focused on the corona radiata and the arcuate fasciculus, two tracts associated with reading and mathematics in a number of previous studies. Using Bayesian hypothesis testing, we show that the present data favor the null model of no differences between groups for these particular tracts—a finding that seems to go against the current view but might be representative of the disparities within this field of research. Together, these findings suggest that structural differences associated with dyslexia and dyscalculia might not be as reliable as previously thought, with potential ramifications in terms of remediation.

•

Previous literature indicates important discrepancies in structural differences associated with dyslexia and dyscalculia

•

We explore the relationship between these disorders and fractional anisotropy, a measure of white matter integrity

•

We show support for the null model in the corona radiata and the arcuate fasciculus

•

This suggests that structural differences associated with these disorders are not as reliable as previously thought

The neural substrates of improved phonological processing following successful treatment in a case of phonological alexia and agraphia

Phonological deficits are common in aphasia after left-hemisphere stroke, and can have significant functional consequences for spoken and written language. While many individuals improve through treatment, the neural substrates supporting improvements are poorly understood. We measured brain activation during pseudoword reading in an individual through two treatment phases. Improvements were associated with greater activation in residual left dorsal language regions and bilateral regions supporting attention and effort. Gains were maintained, while activation returned to pre-treatment levels. This case demonstrates the neural support for improved phonology after damage to critical regions and that improvements may be maintained without markedly increased effort.

Investigating the Influences of Language Delay and/or Familial Risk for Dyslexia on Brain Structure in 5-Year-Olds

Early language delay has often been associated with atypical language/literacy development. Neuroimaging studies further indicate functional disruptions during language and print processing in school-age children with a retrospective report of early language delay. Behavioral data of 114 5-year-olds with a retrospective report of early language delay in infancy (N = 34) and those without (N = 80) and with a familial risk for dyslexia and those without are presented. Behaviorally, children with a retrospective report of early language delay exhibited reduced performance in language/reading-related measures. A voxel-based morphometry analysis in a subset (N = 46) demonstrated an association between reduced gray matter volume and early language delay in left-hemispheric middle temporal, occipital, and frontal regions. Alterations in middle temporal cortex in children with a retrospective report of early language delay were observed regardless of familial risk for dyslexia. Additionally, while children with isolated familial risk for dyslexia showed gray matter reductions in temporoparietal and occipitotemporal regions, these effects were most profound in children with both risk factors. An interaction effect of early language delay and familial risk was revealed in temporoparietal, occipital, and frontal cortex. Our findings support a cumulative effect of early behavioral and genetic risk factors on brain development and may ultimately inform diagnosis/treatment.

Dyslexic Characteristics of Chinese-Speaking Semantic Variant of Primary Progressive Aphasia

Reading disorder is a recognized feature in primary progressive aphasia (PPA). Surface dyslexia, characterized by regularization errors, is typically seen in the English-speaking semantic variant of PPA (svPPA). However, dyslexic characteristics of other languages, particularly logographical languages such as Chinese, remain sparse in the literature. This study aims to characterize and describe the dyslexic pattern in this group of patients by comparing an English-speaking svPPA group with a Chinese-speaking svPPA group. The authors hypothesized that Chinese-speaking individuals with svPPA would likely commit fewer surface dyslexic errors. By accessing the database of Singapore's National Neuroscience Institute and the National Alzheimer's Coordinating Center of the United States, the authors identified three Chinese-speaking and 18 English-speaking patients with svPPA, respectively, for comparison. The results suggest that, instead of surface dyslexia, svPPA in Chinese-speaking individuals is characterized by a profound deep dyslexic error. Based on current evidence suggesting the role of the temporal pole as a semantic convergence center, the authors conclude that this region also mediates and converges lexical-semantic significance in logographical languages.

Brain white matter structure and language ability in preschool-aged children

Brain alterations are associated with reading and language difficulties in older children, but little research has investigated relationships between early language skills and brain white matter structure during the preschool period. We studied 68 children aged 3.0-5.6 years who underwent diffusion tensor imaging and participated in assessments of Phonological Processing and Speeded Naming. Tract-based spatial statistics and tractography revealed relationships between Phonological Processing and diffusion parameters in bilateral ventral white matter pathways and the corpus callosum. Phonological Processing was positively correlated with fractional anisotropy and negatively correlated with mean diffusivity. The relationships observed in left ventral pathways are consistent with studies in older children, and demonstrate that structural markers for language performance are apparent as young as 3 years of age. Our findings in right hemisphere areas that are not as commonly found in adult studies suggest that young children rely on a widespread network for language processing that becomes more specialized with age.

Only time will tell - why temporal information is essential for our neuroscientific understanding of semantics

Theoretical developments about the nature of semantic representations and processes should be accompanied by a discussion of how these theories can be validated on the basis of empirical data. Here, I elaborate on the link between theory and empirical research, highlighting the need for temporal information in order to distinguish fundamental aspects of semantics. The generic point that fast cognitive processes demand fast measurement techniques has been made many times before, although arguably more often in the psychophysiological community than in the metabolic neuroimaging community. Many reviews on the neuroscience of semantics mostly or even exclusively focus on metabolic neuroimaging data. Following an analysis of semantics in terms of the representations and processes involved, I argue that fundamental theoretical debates about the neuroscience of semantics can only be concluded on the basis of data with sufficient temporal resolution. Any "semantic effect" may result from a conflation of long-term memory representations, retrieval and working memory processes, mental imagery, and episodic memory. This poses challenges for all neuroimaging modalities, but especially for those with low temporal resolution. It also throws doubt on the usefulness of contrasts between meaningful and meaningless stimuli, which may differ on a number of semantic and non-semantic dimensions. I will discuss the consequences of this analysis for research on the role of convergence zones or hubs and distributed modal brain networks, top-down modulation of task and context as well as interactivity between levels of the processing hierarchy, for example in the framework of predictive coding.

Same Same But Different: Processing Words in the Aging Brain

Reading is not only one of the most appreciated leisure activities of the elderly but it clearly helps older people to maintain functional independence, which has a significant impact on life quality. Yet, very little is known about how aging affects the neural circuits of the processes that underlie skilled reading. Therefore, the aim of the present study was to systematically investigate the neural correlates of sublexical, orthographic, phonological and lexico-semantic processing in the aging brain. Using functional magnetic resonance imaging, we recorded brain activity of younger (N = 20; 22-35 years) and older (N = 38; 65-76 years) adults during letter identification, lexical decision, phonological decision and semantic categorization. Older and younger adults recruited an identical set of reading-related brain regions suggesting that the general architecture of the reading network is preserved across the lifespan. However, we also observed age-related differences in brain activity in the subcomponents of the reading network. Age-related differences were most prominent during phonological and orthographic processing possibly due to a failure of older adults to inhibit non-optimal reading strategies. Neural effects of aging were also observed outside reading-related circuits, especially in frontal midline regions. These regions might be involved because of their important role in memory, attention and executive control functions and their potential role in resting-state networks.

Neural correlates of the lexicality effect in children

The comparison of words and pseudowords has been extensively used in adult neuroimaging studies to inform neurocognitive models of reading but has rarely been used to inform models of reading acquisition. Using a rhyming judgment task, the current study examined age-related differences in the spelling to sound mapping mechanisms involved in word and pseudoword reading. We hypothesized a developmental increase in specialization of the brain mechanisms engaged for word and pseudoword processing. Consistent with adult studies, children in the current study demonstrated a greater activation for words as compared to pseudowords in the anterior left ventral occipito-temporal cortex (vOT). Inconsistent with adult studies, children also showed greater activation for words as compared to pseudowords in the mid-posterior left vOT, indicating a robust semantic influence on orthographic processing in young readers. Furthermore, our results did not indicate a lexicality by age interaction for 8- to 13-year-old children, suggesting that the adult-like specialization in the left vOT only appears later in development.

The Importance of Handwriting Experience on the Development of the Literate Brain

Handwriting experience can have significant effects on the ability of young children to recognize letters. Why handwriting has this facilitative effect and how this is accomplished were explored in a series of studies using overt behavioral measures and functional neuroimaging of the brain in 4- to 5-year-old children. My colleagues and I showed that early handwriting practice affects visual symbol recognition because it results in the production of variable visual forms that aid in symbol understanding. Further, the mechanisms that support this understanding lay in the communication between visual and motor systems in the brain: Handwriting serves to link visual processing with motor experience, facilitating subsequent letter recognition skills. These results are interpreted in the larger context of the facilitatory effect that learning through action has on perceptual capabilities.

Development of the Visual Word Form Area Requires Visual Experience: Evidence from Blind Braille Readers

Learning to read causes the development of a letter- and word-selective region known as the visual word form area (VWFA) within the human ventral visual object stream. Why does a reading-selective region develop at this anatomical location? According to one hypothesis, the VWFA develops at the nexus of visual inputs from retinotopic cortices and linguistic input from the frontotemporal language network because reading involves extracting linguistic information from visual symbols. Surprisingly, the anatomical location of the VWFA is also active when blind individuals read Braille by touch, suggesting that vision is not required for the development of the VWFA. In this study, we tested the alternative prediction that VWFA development is in fact influenced by visual experience. We predicted that in the absence of vision, the "VWFA" is incorporated into the frontotemporal language network and participates in high-level language processing. Congenitally blind (n = 10, 9 female, 1 male) and sighted control (n = 15, 9 female, 6 male), male and female participants each took part in two functional magnetic resonance imaging experiments: (1) word reading (Braille for blind and print for sighted participants), and (2) listening to spoken sentences of different grammatical complexity (both groups). We find that in blind, but not sighted participants, the anatomical location of the VWFA responds both to written words and to the grammatical complexity of spoken sentences. This suggests that in blindness, this region takes on high-level linguistic functions, becoming less selective for reading. More generally, the current findings suggest that experience during development has a major effect on functional specialization in the human cortex.SIGNIFICANCE STATEMENT The visual word form area (VWFA) is a region in the human cortex that becomes specialized for the recognition of written letters and words. Why does this particular brain region become specialized for reading? We tested the hypothesis that the VWFA develops within the ventral visual stream because reading involves extracting linguistic information from visual symbols. Consistent with this hypothesis, we find that in congenitally blind Braille readers, but not sighted readers of print, the VWFA region is active during grammatical processing of spoken sentences. These results suggest that visual experience contributes to VWFA specialization, and that different neural implementations of reading are possible.

Diagnosing the Neural Circuitry of Reading

We summarize the current state of knowledge of the brain's reading circuits, and then we describe opportunities to use quantitative and reproducible methods for diagnosing these circuits. Neural circuit diagnostics-by which we mean identifying the locations and responses in an individual that differ significantly from measurements in good readers-can help parents and educators select the best remediation strategy. A sustained effort to develop and share diagnostic methods can support the societal goal of improving literacy.

Neurofunctionally dissecting the reading system in children

The reading system can be broken down into four basic subcomponents in charge of prelexical, orthographic, phonological, and lexico-semantic processes. These processes need to jointly work together to become a fluent and efficient reader. Using functional magnetic resonance imaging (fMRI), we systematically analyzed differences in neural activation patterns of these four basic subcomponents in children (N=41, 9-13 years) using tasks specifically tapping each component (letter identification, orthographic decision, phonological decision, and semantic categorization). Regions of interest (ROI) were selected based on a meta-analysis of child reading and included the left ventral occipito-temporal cortex (vOT), left posterior parietal cortex (PPC), left inferior frontal gyrus (IFG), and bilateral supplementary motor area (SMA). Compared to a visual baseline task, enhanced activation in vOT and IFG was observed for all tasks with very little differences between tasks. Activity in the dorsal PPC system was confined to prelexical and phonological processing. Activity in the SMA was found in orthographic, phonological, and lexico-semantic tasks. Our results are consistent with the idea of an early engagement of the vOT accompanied by executive control functions in the frontal system, including the bilateral SMA.

Phonological memory in sign language relies on the visuomotor neural system outside the left hemisphere language network

Sign language is an essential medium for everyday social interaction for deaf people and plays a critical role in verbal learning. In particular, language development in those people should heavily rely on the verbal short-term memory (STM) via sign language. Most previous studies compared neural activations during signed language processing in deaf signers and those during spoken language processing in hearing speakers. For sign language users, it thus remains unclear how visuospatial inputs are converted into the verbal STM operating in the left-hemisphere language network. Using functional magnetic resonance imaging, the present study investigated neural activation while bilinguals of spoken and signed language were engaged in a sequence memory span task. On each trial, participants viewed a nonsense syllable sequence presented either as written letters or as fingerspelling (4-7 syllables in length) and then held the syllable sequence for 12 s. Behavioral analysis revealed that participants relied on phonological memory while holding verbal information regardless of the type of input modality. At the neural level, this maintenance stage broadly activated the left-hemisphere language network, including the inferior frontal gyrus, supplementary motor area, superior temporal gyrus and inferior parietal lobule, for both letter and fingerspelling conditions. Interestingly, while most participants reported that they relied on phonological memory during maintenance, direct comparisons between letters and fingers revealed strikingly different patterns of neural activation during the same period. Namely, the effortful maintenance of fingerspelling inputs relative to letter inputs activated the left superior parietal lobule and dorsal premotor area, i.e., brain regions known to play a role in visuomotor analysis of hand/arm movements. These findings suggest that the dorsal visuomotor neural system subserves verbal learning via sign language by relaying gestural inputs to the classical left-hemisphere language network.

Pathways of the inferior frontal occipital fasciculus in overt speech and reading

In this study, we examined the relationship between tractography-based measures of white matter integrity (ex. fractional anisotropy [FA]) from diffusion tensor imaging (DTI) and five reading-related tasks, including rapid automatized naming (RAN) of letters, digits, and objects, and reading of real words and nonwords. Twenty university students with no reported history of reading difficulties were tested on all five tasks and their performance was correlated with diffusion measures extracted through DTI tractography. A secondary analysis using whole-brain Tract-Based Spatial Statistics (TBSS) was also used to find clusters showing significant negative correlations between reaction time and FA. Results showed a significant relationship between the left inferior fronto-occipital fasciculus FA and performance on the RAN of objects task, as well as a strong relationship to nonword reading, which suggests a role for this tract in slower, non-automatic and/or resource-demanding speech tasks. There were no significant relationships between FA and the faster, more automatic speech tasks (RAN of letters and digits, and real word reading). These findings provide evidence for the role of the inferior fronto-occipital fasciculus in tasks that are highly demanding of orthography-phonology translation (e.g., nonword reading) and semantic processing (e.g., RAN object). This demonstrates the importance of the inferior fronto-occipital fasciculus in basic naming and suggests that this tract may be a sensitive predictor of rapid naming performance within the typical population. We discuss the findings in the context of current models of reading and speech production to further characterize the white matter pathways associated with basic reading processes.

Neurobehavioral consequences of continuous spike and waves during slow sleep (CSWS) in a pediatric population: A pattern of developmental hindrance

INTRODUCTION

Continuous spike and waves during slow sleep (CSWS) is a typical EEG pattern defined as diffuse, bilateral and recently also unilateral or focal localization spike-wave occurring in slow sleep or non-rapid eye movement sleep. Literature results so far point out a progressive deterioration and decline of intellectual functioning in CSWS patients, i.e. a loss of previously normally acquired skills, as well as persistent neurobehavioral disorders, beyond seizure and EEG control. The objective of this study was to shed light on the neurobehavioral impact of CSWS and to identify the potential clinical risk factors for development.

METHODS

We conducted a retrospective study involving a series of 16 CSWS idiopathic patients age 3-16years, considering the entire duration of epilepsy from the onset to the outcome, i.e. remission of CSWS pattern. All patients were longitudinally assessed taking into account clinical (sex, age at onset, lateralization and localization of epileptiform abnormalities, spike wave index, number of antiepileptic drugs) and behavioral features. Intelligent Quotient (IQ) was measured in the whole sample, whereas visuo-spatial attention, visuo-motor skills, short term memory and academic abilities (reading and writing) were tested in 6 out of 16 patients.

RESULTS

Our results showed that the most vulnerable from an intellectual point of view were those children who had an early-onset of CSWS whereas those with later onset resulted less affected (p=0.004). Neuropsychological outcome was better than the behavioral one and the lexical-semantic route in reading and writing resulted more severely affected compared to the phonological route.

CONCLUSIONS

Cognitive deterioration is one but not the only consequence of CSWS. Especially with respect to verbal skills, CSWS is responsible of a pattern of consequences in terms of developmental hindrance, including slowing of development and stagnation, whereas deterioration is rare. Behavioral and academic problems tend to persist beyond epilepsy resolution.