Differential activation of the visual word form area during auditory phoneme perception in youth with dyslexia

Right-Lateralization of the Visual Word Form Area after Left-Hemisphere Perinatal Stroke

In literate adults, an area along the left posterior fusiform gyrus that is often referred to as the "visual word form area" (VWFA) responds particularly strongly to written characters compared with other visually similar stimuli. Theoretical accounts differ in whether they attribute the strong left-lateralization of the VWFA to a left-hemisphere (LH) bias toward visual features used in script, to competition of visual word form processing with that of other visual stimuli processed in the same general cortical territory (especially faces), or to the well established left-lateralization of the language system. Here we used functional magnetic resonance imaging to test the last hypothesis by investigating lateralization of the VWFA in participants (male and female) who have right-hemisphere language due to a large LH perinatal stroke. Demographically matched controls were included for comparison. All participants had intact language skills and were proficient readers; age at testing ranged from 9.75 years to early adulthood. Activation maps contrasting activation during rapid presentation of pseudowords and pictures of places revealed left-lateralized fusiform activation in controls, as expected. In participants with left-hemisphere perinatal stroke and right-lateralized language, the VWFA was instead found in the right fusiform gyrus, despite the fact that the left-hemisphere tissue normally occupied by the VWFA was intact and responded normally to pictures of places. Region-of-interest analyses confirmed right-lateralization for visual word form processing, both relative to place stimuli and relative to a resting baseline. This provides compelling evidence that the lateralization of the VWFA indeed follows that of the frontotemporal language system.

Executive functions-based reading training engages the cingulo-opercular and dorsal attention networks

The aim of this study was to determine the effect of a computerized executive functions (EFs)-based reading intervention on neural circuits supporting EFs and visual attention. Seed-to-voxel functional connectivity analysis was conducted focusing on large-scale attention system brain networks, during an fMRI reading fluency task. Participants were 8- to 12-year-old English-speaking children with dyslexia (n = 43) and typical readers (n = 36) trained on an EFs-based reading training (n = 40) versus math training (n = 39). Training duration was 8 weeks. After the EFs-based reading intervention, children with dyslexia improved their scores in reading rate and visual attention (compared to math intervention). Neurobiologically, children with dyslexia displayed an increase in functional connectivity strength after the intervention between the cingulo-opercular network and occipital and precentral regions. Noteworthy, the functional connectivity indices between these brain regions showed a positive correlation with speed of processing and visual attention scores in both pretest and posttest. The results suggest that reading improvement following an EFs-based reading intervention involves neuroplastic connectivity changes in brain areas related to EFs and primary visual processing in children with dyslexia. Our results highlight the need for training underlying cognitive abilities supporting reading, such as EFs and visual attention, in order to enhance reading abilities in dyslexia.

Learning to Read Strengthens Functional Connectivity Between the Ventral Occipitotemporal Cortex and the Superior Temporal Gyrus During an Auditory Phonological Awareness Task

PURPOSE

It is often assumed that phonological awareness only reflects children's phonological skill. However, orthographic representations have been found to be automatically involved during phonological awareness tasks, which we refer to as automatic orthographic activation. Although previous longitudinal neural studies have addressed how phonological processing during phonological awareness tasks is bidirectionally related to reading skill in developing children, we do not know how automatic orthographic activation plays a role in reading skill.

METHOD

To address this gap, we measured 40 children's reading skill and brain activity during an auditory phonological task at two time points using functional magnetic resonance imaging. Children were 5.5 to 6.5 years old at the first time point and were followed up approximately 1.5 years later when they were 7 to 8 years old.

RESULTS

We found that earlier reading skill predicted children's later functional connectivity during onset processing between the left superior temporal gyrus, a phonological region, and the left posterior ventral occipitotemporal cortex, an orthographic region representing letters.

CONCLUSION

This finding, together with previous studies, suggests that learning to read influences phonological awareness not only by refining phonological representations but also via strengthening the automatic mapping between phonemes and letters during spoken language processing.

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.

A sculpting effect of reading on later representational quality of phonology revealed by multi-voxel pattern analysis in young children

Using univariate analysis, a previous study by Wang et al. (2020) found a scaffolding effect of earlier phonological representation in superior temporal gyrus (STG) on later reading skill but failed to observe a sculpting effect of earlier reading on later phonological representation. The current study applied multi-voxel pattern analysis (MVPA) to examine if both scaffolding and sculpting effects were present in young children. We found that better initial reading skill predicted higher decoding coefficient of brain activity patterns for phonological representations in STG. This sculpting effect was present only for decoding small grain sizes (phonemes) and in younger children (6- to 7.5-year-olds), as we did not find any effects for large grain sizes (rhymes) or older children (7.5- to 9.5-year-olds). Although a scaffolding effect was not observed, the current study provides the first neural evidence of how earlier reading sculpts later phonological awareness in beginning readers.

Extraction of discriminative features from EEG signals of dyslexic children; before and after the treatment

Dyslexia is a neurological disorder manifested as difficulty reading and writing. It can occur despite adequate instruction, intelligence, and intact sensory abilities. Different electroencephalogram (EEG) patterns have been demonstrated between dyslexic and healthy subjects in previous studies. This study focuses on the difference between patients before and after treatment. The main goal is to identify the subset of features that adequately discriminate subjects before and after a specific treatment plan. The treatment consists of Transcranial Direct Current Stimulation (tDCS) and occupational therapy using the BrainWare SAFARI software. The EEG signals of sixteen dyslexic children were recorded during the eyes-closed resting state before and after treatment. The preprocessing step was followed by the extraction of a wide range of features to investigate the differences related to the treatment. An optimal subset of features extracted from recorded EEG signals was determined using Principal Component Analysis (PCA) in conjunction with the Sequential Floating Forward Selection (SFFS) algorithm. The results showed that treatment leads to significant changes in EEG features like spectral and phase-related EEG features, in various regions. It has been demonstrated that the extracted subset of discriminative features can be useful for classification applications in treatment assessment. The most discriminative subset of features could classify the data with an accuracy of 92% with SVM classifier. The above result confirms the efficacy of the treatment plans in improving dyslexic children's cognitive skills.

Brain responses during auditory word recognition vary with reading ability in Chinese school-age children

While the close relationship between the brain system for speech processing and reading development is well-documented in alphabetic languages, whether and how such a link exists in children in a language without systematic grapheme-phoneme correspondence has not been directly investigated. In the present study, we measured Chinese children's brain activation during an auditory lexical decision task with functional magnetic resonance imaging. The results showed that brain areas distributed across the temporal and frontal lobes activated during spoken word recognition. In addition, the left occipitotemporal cortex (OTC) was recruited, especially under the real word condition, thus confirming the involvement of this orthographic-related area in spoken language processing in Chinese children. Importantly, activation of the left temporoparietal cortex (TPC) in response to words and pseudowords was positively correlated with children's reading ability, thus supporting the salient role phonological processing plays in Chinese reading in the developing brain. Furthermore, children with higher reading scores also increasingly recruited the left anterior OTC to make decisions on the lexical status of pseudowords, indicating that higher-skill children tend to search abstract lexical representations more deeply than lower-skill children in deciding whether spoken syllables are real. In contrast, the precuneus was more related to trial-by-trial reaction time in lower-skill children, suggesting that effort-related neural systems differ among pupils with varying reading abilities. Taken together, these findings suggest a strong link between the neural correlates of speech processing and reading ability in Chinese children, thus supporting a universal basis underlying reading development across languages.

Brain-behavior dynamics between the left fusiform and reading

The visual word form area (VWFA) plays a significant role in the development of reading skills. However, the developmental course and anatomical properties of the VWFA have only limitedly been investigated. The aim of the current longitudinal MRI study was to investigate dynamic, bidirectional relations between reading, and the structure of the left fusiform gyrus at the early-to-advanced reading stage. More specifically, by means of bivariate correlations and a cross-lagged panel model (CLPM), the interrelations between the size of the left fusiform gyrus and reading skills (an average score of a word and pseudo-word reading task) were studied in a longitudinal cohort of 43 Flemish children (29M, 14F) with variable reading skills in grade 2 (the early stage of reading) and grade 5 (the advanced stage of reading) of primary school. Results revealed that better reading skills at grade 2 lead to a larger size of the left fusiform gyrus at grade 5, whereas there are no directional effects between the size of the left fusiform gyrus at grade 2 and reading skills at grade 5. Hence, according to our results, there is behavior-driven brain plasticity and no brain-driven reading change between the early and advanced stage of reading. Together with pre-reading brain studies showing predictive relations to later reading scores, our results suggest that the direction of brain-behavioral influences changes throughout the course of reading development.

Effect of computer-based multisensory program on English reading skills of students with Dyslexia and reading difficulties

The study evaluated the effectiveness of a computer-based Multi-Sensory Program (MSP) on English reading skills as a second language of fourth-grade students with reading difficulties and Dyslexia in the United Arab Emirates (UAE). Pretest-Posttest experimental design was used in this study. The analysis showed that average pretest score in both the experimental and control groups was almost the same and the average post-test score was much higher in the experimental group as compared to the control group. Moreover, results also reveal statistically significant difference in the students' mean scores between the experimental and control groups after the MSP intervention. The study has implications in the UAE and Arab countries and everywhere in the world for students who are learning English as a second language and facing reading difficulties. Besides, the modified MSP used in this study can be adopted and imitated to create a local version in the Arabic language in the Middle East and in other countries that are teaching Arabic as a second language.