Right Structural and Functional Reorganization in Four-Year-Old Children with Perinatal Arterial Ischemic Stroke Predict Language Production.

Brain imaging methods have contributed to shed light on the mechanisms of recovery after early brain insult. The assumption that the unaffected right hemisphere can take over language functions after left perinatal stroke is still under debate. Here, we report how patterns of brain structural and functional reorganization were associated with language outcomes in a group of four-year-old children with left perinatal arterial ischemic stroke (PAIS). Specifically, we gathered specific fine-grained developmental measures of receptive and productive aspects of language as well as standardized measures of cognitive development. We also collected structural neuroimaging data as well as functional activations during a passive listening story-telling fMRI task and a resting state session (rs-fMRI). Children with a left perinatal stroke showed larger lateralization indices of both structural and functional connectivity of the dorsal language pathway towards the right hemisphere that, in turn, were associated with better language outcomes. Importantly, the pattern of structural asymmetry was significantly more right-lateralized in children with a left perinatal brain insult than in a group of matched healthy controls. These results strongly suggest that early lesions of the left dorsal pathway and the associated perisylvian regions can induce the interhemispheric transfer of language functions to right homolog regions. This study provides combined evidence of structural and functional brain reorganization of language networks after early stroke with strong implications for neurobiological models of language development.

Language learning and brain reorganization in a 3.5-year-old child with left perinatal stroke revealed using structural and functional connectivity.

Brain imaging methods have contributed to shed light on the possible mechanisms of recovery and cortical reorganization after early brain insult. The idea that a functional left hemisphere is crucial for achieving a normalized pattern of language development after left perinatal stroke is still under debate. We report the case of a 3.5-year-old boy born at term with a perinatal ischemic stroke of the left middle cerebral artery, affecting mainly the supramarginal gyrus, superior parietal and insular cortex extending to the precentral and postcentral gyri. Neurocognitive development was assessed at 25 and 42 months of age. Language outcomes were more extensively evaluated at the latter age with measures on receptive vocabulary, phonological whole-word production and linguistic complexity in spontaneous speech. Word learning abilities were assessed using a fast-mapping task to assess immediate and delayed recall of newly mapped words. Functional and structural imaging data as well as a measure of intrinsic connectivity were also acquired. While cognitive, motor and language levels from the Bayley Scales fell within the average range at 25 months, language scores were below at 42 months. Receptive vocabulary fell within normal limits but whole word production was delayed and the child had limited spontaneous speech. Critically, the child showed clear difficulties in both the immediate and delayed recall of the novel words, significantly differing from an age-matched control group. Neuroimaging data revealed spared classical cortical language areas but an affected left dorsal white-matter pathway together with right lateralized functional activations. In the framework of the model for Social Communication and Language Development, these data confirm the important role of the left arcuate fasciculus in understanding and producing morpho-syntactic elements in sentences beyond two word combinations and, most importantly, in learning novel word-referent associations, a building block of language acquisition.

Desarrollo léxico en el prematuro: medidas del vocabulario expresivo en el segundo año de vida / Lexical development in preterms: expressive vocabulary measures in the second year of life

Diversos trabajos previos han mostrado que el desarrollo léxico y gramatical puede estar comprometido en niños nacidos muy prematuramente, aunque los resultados de distintas investigaciones no siempre resultan coincidentes. Se presentan aquí los resultados de una muestra de niños sanos, nacidos muy prematuramente ≤ 32 semanas gestación y ≤ 1.500 g de peso al nacer), en los que se obtuvieron medidas del vocabulario expresivo a los 12, 18 y 24 meses (edad corregida por gestación) mediante el Inventario de Desarrollo Comunicativo MacArthur. Los datos de esta muestra se comparan con los obtenidos por tres grupos independientes de nacidos a término, procedentes del mismo hospital y comparables en lengua familiar y estatus socioeconómico. Los resultados muestran diferencias significativas en el vocabulario total expresivo alcanzado a los 18 y los 24 meses, pero no así en el primer nivel de edad analizado. En la composición del vocabulario, distinguiendo entre rutinas, nombres, predicados y palabras gramaticales, observamos diferencias significativas en todas las categorías a los 18 meses, aunque a los 24 meses sólo se mantienen las diferencias relativas a rutinas y nombres. En un segundo análisis de los datos, dividiendo la muestra según el sexo, se comprueba que, tanto a los 18 como a los 24 meses, las diferencias significativas entre prematuros y controles se sitúan exclusivamente en la muestra de niños y se manifestaban en todas las categorías analizadas. En conjunto, estos resultados apuntan a un ritmo inicial de crecimiento léxico (expresivo) más lento en el prematuro, sólo aparente a partir de los 18 meses y con mayor incidencia en la población masculina. Se discute el valor de estos datos en relación con el desarrollo lingüístico posterior en esta población de riesgo (AU)

Previous research has shown that lexical and grammatical development may be compromised in very preterm infants, although results from different studies are not always coincident. Expressive lexicon measures were obtained in a sample of healthy very preterm infants (≤ 32 gestation weeks and birth weight ≤ 1500 g), using the MacArthur Communicative Development Inventory at 12, 18 and 24 months of age (corrected for gestation). Data from this sample were compared with results from three independent groups of full term infants born in the same hospital and with comparable language background and socioeconomic status. Significant differences were found in total number of words produced at 18 and 24 months of age, but not at the first age level under analysis. Regarding vocabulary composition, significant differences were observed in all categories under study (social words, nouns, predicates and function words) at 18 months of age, but at 24 months significant differences were restricted to the categories of social words and nouns. Further analysis of the data by gender revealed that differences between full term and preterm infants reached significance in the male subgroup, both at 18 and 24 months of age and for all lexical categories. Taken together these results suggest an initially slower expressive lexicon development in the population of infants born preterm, but differences are only evident from age 18 months and with a higher incidence in the male subgroup. The paper discusses the predictive value of these data for later language outcomes in this at risk population (AU)