Neural patterns of word processing differ in children with dyslexia and isolated spelling deficit.

There is an ongoing debate concerning the extent to which deficits in reading and spelling share cognitive components and whether they rely, in a similar fashion, on sublexical and lexical pathways of word processing. The present study investigates whether the neural substrates of word processing differ in children with various patterns of reading and spelling deficits. Using functional magnetic resonance imaging, we compared written and auditory processing in three groups of 9-13-year olds (N = 104): (1) with age-adequate reading and spelling skills; (2) with reading and spelling deficits (i.e., dyslexia); (3) with isolated spelling deficits but without reading deficits. In visual word processing, both deficit groups showed hypoactivations in the posterior superior temporal cortex compared to typical readers and spellers. Only children with dyslexia exhibited hypoactivations in the ventral occipito-temporal cortex compared to the two groups of typical readers. This is the result of an atypical pattern of higher activity in the occipito-temporal cortex for non-linguistic visual stimuli than for words, indicating lower selectivity. The print-speech convergence was reduced in the two deficit groups. Impairments in lexico-orthographic regions in a reading-based task were associated primarily with reading deficits, whereas alterations in the sublexical word processing route could be considered common for both reading and spelling deficits. These findings highlight the partly distinct alterations of the language network related to reading and spelling deficits.

Reading and spelling skills are differentially related to phonological processing: Behavioral and fMRI study.

The manuscript reports a study on a large sample (N = 170) of Polish speaking 8-13 year old children, whose brain activation was measured in relation to tasks that require auditory phonological processing. We aimed to relate brain activation to individual differences in reading and spelling. We found that individual proficiency in both reading and spelling significantly correlated with activation of the left ventral occipito-temporal cortex encompassing the Visual Word Form Area which has been implicated in automatic orthographic activations. Reading but not spelling was found to correlate with activation in the left anterior dorsal stream (anterior supramarginal and postcentral gyri). Our results indicate that the level of both reading and spelling is related to activity in areas involved in the storage of fine-grained orthographic representations. However, only the reading level is uniquely related to activity of regions responsible for the articulation, motor planning and grapheme-to-phoneme correspondence, which form the basis for effective decoding skill.

Dyslexia and age related effects in the neurometabolites concentration in the visual and temporo-parietal cortex.

Several etiological theories, in particular neuronal noise and impaired auditory sampling, predicted neurotransmission deficits in dyslexia. Neurometabolites also affect white matter microstructure, where abnormalities were previously reported in dyslexia. However findings from only few magnetic resonance spectroscopy studies using diverse age groups, different brain regions, data processing and reference scaling are inconsistent. We used MEGA-PRESS single-voxel spectroscopy in two ROIs: left temporo-parietal and occipital cortex in 36 adults and 52 children, where half in each group had dyslexia. Dyslexics, on average, had significantly lower total N-acetylaspartate (tNAA) than controls in the occipital cortex. Adults compared to children were characterized by higher choline and creatine in both areas, higher tNAA in left temporo-parietal and lower glutamate in the visual cortex, reflecting maturational changes in cortical microstructure and metabolism. Although the current findings do not support the proposed etiological theories of dyslexia, they show, for the first time, that tNAA, considered to be a neurochemical correlate of white matter integrity, is deficient in the visual cortex in both children and adults with dyslexia. They also point that several neurotransmitters, including ones previously used as reference, change with age.

Neither action nor phonological video games make dyslexic children read better.

The prevalence and long-term consequences of dyslexia make it crucial to look for effective and efficient ways of its therapy. Action video games (AVG) were implied as a possible remedy for difficulties in reading in Italian and English-speaking children. However, the studies examining the effectiveness of AVG application in dyslexia suffered from significant methodological weaknesses such as small sample sizes and lack of a control group with no intervention. In our study, we tested how two forms of training: based on AVG and on phonological non-action video games (PNAVG), affect reading in a group of fifty-four Polish children with dyslexia. Both speed and accuracy of reading increased in AVG as much as in PNAVG group. Moreover, both groups improved in phonological awareness, selective attention and rapid naming. Critically, the reading progress in the two groups did not differ from a dyslexic control group which did not participate in any training. Thus, the observed improvement in reading in AVG and PNAVG can be attributed either to the normal reading development related to schooling or to test practice effect. Overall, we failed to replicate previous studies: Neither AVG nor PNAVG remedy difficulties in reading in school children.

How Does L1 and L2 Exposure Impact L1 Performance in Bilingual Children? Evidence from Polish-English Migrants to the United Kingdom.

Most studies on bilingual language development focus on children's second language (L2). Here, we investigated first language (L1) development of Polish-English early migrant bilinguals in four domains: vocabulary, grammar, phonological processing, and discourse. We first compared Polish language skills between bilinguals and their Polish non-migrant monolingual peers, and then investigated the influence of the cumulative exposure to L1 and L2 on bilinguals' performance. We then examined whether high exposure to L1 could possibly minimize the gap between monolinguals and bilinguals. We analyzed data from 233 typically developing children (88 bilingual and 145 monolingual) aged 4;0 to 7;5 (years;months) on six language measures in Polish: receptive vocabulary, productive vocabulary, receptive grammar, productive grammar (sentence repetition), phonological processing (non-word repetition), and discourse abilities (narration). Information about language exposure was obtained via parental questionnaires. For each language task, we analyzed the data from the subsample of bilinguals who had completed all the tasks in question and from monolinguals matched one-on-one to the bilingual group on age, SES (measured by years of mother's education), gender, non-verbal IQ, and short-term memory. The bilingual children scored lower than monolinguals in all language domains, except discourse. The group differences were more pronounced on the productive tasks (vocabulary, grammar, and phonological processing) and moderate on the receptive tasks (vocabulary and grammar). L1 exposure correlated positively with the vocabulary size and phonological processing. Grammar scores were not related to the levels of L1 exposure, but were predicted by general cognitive abilities. L2 exposure negatively influenced productive grammar in L1, suggesting possible L2 transfer effects on L1 grammatical performance. Children's narrative skills benefitted from exposure to two languages: both L1 and L2 exposure influenced story structure scores in L1. Importantly, we did not find any evidence (in any of the tasks in which the gap was present) that the performance gap between monolinguals and bilinguals could be fully closed with high amounts of L1 input.

Home Language Will Not Take Care of Itself: Vocabulary Knowledge in Trilingual Children in the United Kingdom.

Language input is crucial for language acquisition and especially for children's vocabulary size. Bilingual children receive reduced input in each of their languages, compared to monolinguals, and are reported to have smaller vocabularies, at least in one of their languages. Vocabulary acquisition in trilingual children has been largely understudied; only a few case studies have been published so far. Moreover, trilingual language acquisition in children has been rarely contrasted with language outcomes of bilingual and monolingual peers. We present a comparison of trilingual, bilingual, and monolingual children (total of 56 participants, aged 4;5-6;7, matched one-to-one for age, gender, and non-verbal IQ) in regard to their receptive and expressive vocabulary (measured by standardized tests), and relative frequency of input in each language (measured by parental report). The monolingual children were speakers of Polish or English, while the bilinguals and trilinguals were migrant children living in the United Kingdom, speaking English as a majority language and Polish as a home language. The trilinguals had another (third) language at home. For the majority language, English, no differences were found across the three groups, either in the receptive or productive vocabulary. The groups differed, however, in their performance in Polish, the home language. The trilinguals had lower receptive vocabulary than the monolinguals, and lower productive vocabulary compared to the monolinguals. The trilinguals showed similar lexical knowledge to the bilinguals. The bilinguals demonstrated lower scores than the monolinguals, but only in productive vocabulary. The data on reported language input show that input in English in bilingual and trilingual groups is similar, but the bilinguals outscore the trilinguals in relative frequency of Polish input. Overall, the results suggest that in the majority language, multilingual children may develop lexical skills similar to those of their monolingual peers. However, their minority language is weaker: the trilinguals scored lower than the Polish monolinguals on both receptive and expressive vocabulary tests, and the bilinguals showed reduced expressive knowledge but leveled out with the Polish monolinguals on receptive vocabulary. The results should encourage parents of migrant children to support home language(s), if the languages are to be retained in a longer perspective.