Development of the N400 for Word Learning in the First 2 Years of Life: A Systematic Review.

The N400 ERP component is a direct neural index of word meaning. Studies show that the N400 component is already present in early infancy, albeit often delayed. Many researchers capitalize on this finding, using the N400 component to better understand how early language acquisition unfolds. However, variability in how researchers quantify the N400 makes it difficult to set clear predictions or build theory. Not much is known about how the N400 component develops in the first 2 years of life in terms of its latency and topographical distributions, nor do we know how task parameters affect its appearance. In the current paper we carry out a systematic review, comparing over 30 studies that report the N400 component as a proxy of semantic processing elicited in infants between 0 and 24 months old who listened to linguistic stimuli. Our main finding is that there is large heterogeneity across semantic-priming studies in reported characteristics of the N400, both with respect to latency and to distributions. With age, the onset of the N400 insignificantly decreases, while its offset slightly increases. We also examined whether the N400 appears different for recently-acquired novel words vs. existing words: both situations reveal heterogeneity across studies. Finally, we inspected whether the N400 was modulated differently with studies using a between-subject design. In infants with more proficient language skills the N400 was more often present or showed itself here with earlier latency, compared to their peers; but no consistent patterns were observed for distribution characteristics of the N400. One limitation of the current review is that we compared studies that widely differed in choice of EEG recordings, pre-processing steps and quantification of the N400, all of which could affect the characteristics of the infant N400. The field is still missing research that systematically tests development of the N400 using the same paradigm across infancy.

Cerebellar volumes and language functions in school-aged children born very preterm.

BACKGROUND: Volumes of cerebellar posterior lobes have been associated with cognitive skills, such as language functioning. Children born very preterm (VPT) often have language problems. However, only total cerebellar volume has been associated with language functioning, with contradicting results. The objective of this study was to ascertain whether total cerebellar structures or specific posterior lobular structures are associated with language ability of school-aged VPT children. METHODS: This is a prospective cohort study of 42 school-aged VPT children without major handicaps. Structural MRI was performed and the cerebellum segmentation pipeline was used for segmentation of separate lobules. Narrative retelling assessment was performed and language content and language structure scores were extracted. Linear regression analyses were used to associate language scores with whole gray matter (GM) cerebellar volume and right Crus I+II GM volume. RESULTS: Whole cerebellar GM volume was not significantly associated with language content nor with language structure; however, right Crus I+II GM volume was significantly associated with language content (ß = 0.192 (CI = 0.033, 0.351), p = 0.020). CONCLUSIONS: GM volume of Crus I+II appears to be associated with language functions in school-aged VPT children without major handicaps, while whole cerebellar volume is not. This study showed the importance of studying cerebellar lobules separately, rather than whole cerebellar volume only, in relation to VPT children's language functions. IMPACT: GM volume of Crus I+II is associated with semantic language functions in school-aged very preterm children without overt brain injury, whereas whole cerebellar volume is not. This study showed the importance of studying cerebellar lobules separately, rather than whole cerebellar volume only, in relation to very preterm children's language functions. This study might impact future research in very preterm children. Lobular structures rather than whole cerebellar structures should be the region of interest in relation to language functions.

Sequential Multilingualism and Cognitive Abilities: Preliminary Data on the Contribution of Language Proficiency and Use in Different Modalities.

This exploratory study focuses on sequential bi-/multilinguals (specifically, nonimmigrant young Dutch native speakers who learned at least one foreign language (FL) at or after the age of 5) and investigates the impact of proficiency-based and amount-of-use-based degrees of multilingualism in different modalities (i.e., speaking, listening, writing, reading) on inhibition, disengagement of attention, and switching. Fifty-four participants completed a comprehensive background questionnaire, a nonverbal fluid intelligence task, a Flanker task, and the Trail Making Test. Correlational and regression analyses considering multilingualism related variables and other variables that may contribute to the cognitive abilities under investigation (e.g., years of formal education, socioeconomic status, physical activity, playing video-games) revealed that only proficiency-based degrees of multilingualism impacted cognitive abilities. Particularly, mean FL writing proficiency affected inhibition (i.e., significant positive flanker effect) and L2 listening proficiency influenced disengagement of attention (i.e., significant negative sequential congruency effect). Our findings suggest that only those speakers who have reached a certain proficiency threshold in more than one FL show a cognitive advantage, which, in our sample, emerged in inhibition only. Furthermore, our study suggests that, regarding the impact of proficiency-based degrees of multilingualism on cognitive abilities, for our participants the writing and listening modalities mattered most.