Word Decoding Abilities of 1st Graders with Developmental Dyslexia Considering Reading Severity and Word and Syllable Structure

Objectives: This study investigated word decoding abilities of 1st graders with Developmental dyslexia according to the level of decoding difficulty, meaning availability, word and syllable structure.Methods: Twenty Korean 1st graders with developmental dyslexia participated in 40 word-reading tasks individually. All of them had severe decoding difficulties, even with normal listening comprehension (KORLA; Pae et al., 2015) and intelligence (K-CTONI-2; Park, 2014). The group differences by decoding difficulties were compared considering the meaning of words, the number of syllable-final graphemes, and the position of each grapheme in a syllable.Results: Both the severe and less-severe group in Korean word-decoding difficulties revealed the gaps between word reading and nonword reading. Both groups had decoding difficulties when a word had syllable-final graphemes, while the severe group had even lower performances in word readings with 2 syllable-final graphemes. Both groups showed similar performances in reading syllable-initial graphemes while the severe group had lower performances both in reading syllable-medial vowel graphemes and syllable-final consonant graphemes compared to the less-severe group.Conclusion: Korean 1st graders with developmental dyslexia seemed to be in urgent need of decoding support considering word and syllable structure. Triggering the non-lexical route with non-words considering the grain size of syllable-medial vowel graphemes and syllable-final graphemes would facilitate word decoding abilities of severely dyslexic Korean children.

A Spatiotemporal Map of Reading Aloud

Reading words aloud is a foundational aspect of the acquisition of literacy. The rapid rate at which multiple distributed neural substrates are engaged in this process can only be probed via techniques with high spatiotemporal resolution. We used direct intracranial recordings in a large cohort to create a holistic yet fine-grained map of word processing, enabling us to derive the spatiotemporal neural codes of multiple word attributes critical to reading: lexicality, word frequency and orthographic neighborhood. We found that lexicality is encoded by early activity in mid-fusiform (mFus) cortex and precentral sulcus. Word frequency is also first represented in mFus followed by later engagement of the inferior frontal gyrus (IFG) and inferior parietal sulcus (IPS), and orthographic neighborhood is encoded solely in the IPS. A lexicality decoder revealed high weightings for electrodes in the mFus, IPS, anterior IFG and the pre-central sulcus. These results elaborate the neural codes underpinning extant dual-route models of reading, with parallel processing via the lexical route, progressing from mFus to IFG, and the sub-lexical route, progressing from IPS to anterior IFG.

DUAL-tDCS Treatment over the Temporo-Parietal Cortex Enhances Writing Skills: First Evidence from Chronic Post-Stroke Aphasia

The learning of writing skills involves the re-engagement of previously established independent procedures. Indeed, the writing deficit an adult may acquire after left hemispheric brain injury is caused by either an impairment to the lexical route, which processes words as a whole, to the sublexical procedure based on phoneme-to-grapheme conversion rules, or to both procedures. To date, several approaches have been proposed for writing disorders, among which, interventions aimed at restoring the sub-lexical procedure were successful in cases of severe agraphia. In a randomized double-blind crossover design, fourteen chronic Italian post-stroke aphasics underwent dual transcranial direct current stimulation (tDCS) (20 min, 2 mA) with anodal and cathodal current simultaneously placed over the left and right temporo-parietal cortex, respectively. Two different conditions were considered: (1) real, and (2) sham, while performing a writing task. Each experimental condition was performed for ten workdays over two weeks. After real stimulation, a greater amelioration in writing with respect to the sham was found. Relevantly, these effects generalized to different language tasks not directly treated. This evidence suggests, for the first time, that dual tDCS associated with training is efficacious for severe agraphia. Our results confirm the critical role of the temporo-parietal cortex in writing skills.

Effects of individual differences in lexical quality: Neighbourhood effects in naming

Two experiments investigated individual differences in the neighbourhood density effect shown during the production of written words and pseudowords. Word and pseudoword targets with dense and sparse neighbourhoods were used in a masked form priming experiment with 84 universitystudents. In addition, individual difference measures of language and cognitive processes were collected, and a principal component analysis was used to group these data into factors. Overall, we observed facilitatory form priming effects for word and pseudoword targets. However, the facilitatory form priming was larger for pseudoword targets and word targets with sparse neighbourhoods compared to those with dense neighbourhoods. Form priming of word targets was also affected by a factor linking to orthographic precision: For people with low orthographic precision, word targets with dense neighbourhoods preceded by word primes showed stronger facilitatory priming than those thatfollowed pseudoword primes. The opposite pattern was shown for word targets with sparse neighbourhoods. People with high orthographic precision only showed facilitatory priming. Facilitatory form priming for pseudoword targets preceded by pseudoword primes was smaller than for those that followed word primes in people with low orthographic precision. The opposite patternwas found for people with high orthographic precision. These results suggest that people with high orthographic precision rely more on the lexical route than the sublexical route and the opposite is the case for people with low orthographic precision. The implications for theories of masked priming in production and the Lexical Quality Hypothesis applied to reading skill are discussed.

Delineating the cognitive-neural substrates of writing: a large scale behavioral and voxel based morphometry study

The current study investigated the cognitive and neural substrates that underpin writing ability. We explored similarities and differences in writing numbers and words and compared these to language and manual actions in a large group of sub-acute, stroke patients (n = 740). The behavioral data showed association and dissociation in the ability to write words and numbers. Comorbidities of writing deficits with both language and motor impairments were prevalent, with less than a handful showing deficits restricted to the writing tasks. A second analysis with a subset of patients (n = 267) explored the neural networks that mediate writing abilities. Lesion to right temporal contributed to writing words, while lesions to left postcentral contributed to writing numbers. Overlapping neural mechanisms included the bilateral prefrontal cortex, right inferior parietal, left middle occipital and the right cerebellum. With the former regions associated with error pattern typical to writing based on prior knowledge (the lexical route), while lesion to left MOG was associated with errors to the phonological (non-lexical) route. Using principle components extracted from the behavioral data, we showed that right prefrontal and right parietal contributed to the ability to use pen, while lesion to bilateral prefrontal, inferior temporal and cerebellum supported unique use of pen for writing. The behavioral and imaging data suggested that writing numbers and words primarily relied on overlapping cognitive and neural functions. Incidents of pure writing deficits, in the absence of motor or language deficits were rare. Nevertheless, the PCA and neural data suggested that writing abilities were associated with some unique neuro-cognitive functions, specifically dedicated to the use of pen and the ability to transform meaning to motor command.

Taking the sub-lexical route: brain dynamics of reading in the semantic variant of Primary Progressive Aphasia

Reading aloud requires mapping an orthographic form to a phonological one. The mapping process relies on sub-lexical statistical regularities (e.g., “oo” to |u□|) or on learned lexical associations between a specific visual form and a series of sounds (e.g., yacht to /j□t/). Computational, neuroimaging, and neuropsychological evidence suggest that sub-lexical, phonological and lexico-semantic processes rely on partially distinct neural substrates: a dorsal (occipito-parietal) and a ventral (occipito-temporal) route, respectively.Here, we investigated the spatiotemporal features of orthography-to-phonology mapping, capitalizing on the time resolution of magnetoencephalography and the unique clinical model offered by patients with semantic variant of Primary Progressive Aphasia (svPPA). Behaviorally, svPPA patients manifest marked lexico-semantic impairments including difficulties in reading words with exceptional orthographic to phonological correspondence (irregular words). Moreover, they present with focal neurodegeneration in the anterior temporal lobe (ATL), affecting primarily the ventral, occipito-temporal, lexical route. Therefore, this clinical population allows for testing of specific hypotheses on the neural implementation of the dualroute model for reading, such as whether damage to one route can be compensated by over-reliance on the other. To this end, we reconstructed and analyzed time-resolved whole-brain activity in 12 svPPA patients and 12 healthy age-matched controls while reading irregular words (e.g., yacht) and pseudowords (e.g., pook).Consistent with previous findings that the dorsal route is involved in sub-lexical, phonological processes, in control participants we observed enhanced neural activity over dorsal occipito-parietal cortices for pseudowords, when compared to irregular words. This activation was manifested in the beta-band (12-30 Hz), ramping up slowly over 500 ms after stimulus onset and peaking at ∼800 ms, around response selection and production. Consistent with our prediction, svPPA patients did not exhibit this temporal pattern of neural activity observed in controls this contrast. Furthermore, a direct comparison of neural activity between patients and controls revealed a dorsal spatiotemporal cluster during irregular word reading. These findings suggest that the sub-lexical/phonological route is involved in processing both irregular and pseudowords in svPPA.Together these results provide further evidence supporting a dual-route model for reading aloud mediated by the interplay between lexico-semantic and sub-lexical/phonological neuro-cognitive systems. When the ventral route is damaged, as in the case of neurodegeneration affecting the ATL, partial compensation appears to be possible by over-recruitment of the slower, serial attention-dependent, dorsal one.Abbreviated SummaryBorghesani et al. investigate brain dynamics during irregular word reading using magnetoencephalographic imaging in patients with semantic variant of primary progressive aphasia. Due to ventral anterior temporal lobe neurodegeneration, patients show greater reliance of dorsal, occipito-parietal brain regions – providing novel evidence for the interplay between ventral and dorsal routes for reading.

Unpredictability and complexity of print-to-speech correspondences increase reliance on lexical processes: more evidence for the orthographic depth hypothesis

The Orthographic Depth Hypothesis [Katz, L., & Frost, R. (1992). The reading process is different for different orthographies: The orthographic depth hypothesis. In R. Frost & L. Katz (Eds.), Orthography, phonology, morphology, and meaning (pp. 67–84). Amsterdam: Elsevier Science] proposes cross-linguistic differences in the involvement of lexical processing during reading. In orthographies with complex, inconsistent, and/or incomplete sublexical correspondences, decoding is more difficult and therefore slower. This gives more time to the lexical route to retrieve information, and leads to a greater ratio of lexical processing. We test whether this mechanism applies both for words with inconsistent (in English) and for words with complex (in French) correspondences. As complex correspondences are sufficient to derive a correct pronunciation, an increase in lexical processing may not occur. In a reading-aloud task, we used the frequency effect to measure lexical processing. The data showed stronger involvement of lexical processing for inconsistent compared to consistent words, and for complex compared to simple words. The results confirm that Katz and Frost’s proposed mechanism applies to different sources of orthographic depth.

The use and nature of grapheme coding during sub-lexical processing and lexical access

This work aimed to investigate grapheme coding during sub-lexical processing and lexical access. Using the letter detection task in Experiment 1, we compared letter pairs that could be considered as a grapheme unit or not depending on context (referred to as weakly cohesive complex, e.g., an in chant vs cane) to real two-letter graphemes (highly cohesive complex, e.g., au in chaud) and single-letter graphemes (simple, e.g., a in place). Three experimental conditions were used, one of which was designed to prevent phonological influences. Data revealed that only highly cohesive complex graphemes were processed as units, not the weakly cohesive ones. The same pattern was found across experimental conditions in favor of an orthographic mechanism. In Experiments 2 and 3, a primed lexical decision task was used with two stimulus onset asynchronies (SOAs) and two different ranges of lexical frequency. We manipulated the number of graphemes removed from partial primes ( d**che vs do**he-DOUCHE) and relatedness. In contrast to Experiment 1, no evidence was provided in favor of a role of graphemes during lexical access. We suggest that graphemes can be conceived as sub-lexical orthographic units per se but can only be captured within a sub-lexical route to reading.

The Means to an End: Phonology's Prominence in a Reading Task

For decades, psycholinguists have engaged in a debate over the steps involved in the reading process. Do readers find meaning in texts through a phonological route or a lexical route? This paper, which takes into account two previous studies, investigates the influence of phonology and lexical spelling by analyzing the results of a reading judgment task.