The neurophysiology of closed-loop auditory stimulation in sleep: A magnetoencephalography study.

Closed-loop auditory stimulation (CLAS) is a brain modulation technique in which sounds are timed to enhance or disrupt endogenous neurophysiological events. CLAS of slow oscillation up-states in sleep is becoming a popular tool to study and enhance sleep's functions, as it increases slow oscillations, evokes sleep spindles and enhances memory consolidation of certain tasks. However, few studies have examined the specific neurophysiological mechanisms involved in CLAS, in part because of practical limitations to available tools. To evaluate evidence for possible models of how sound stimulation during brain up-states alters brain activity, we simultaneously recorded electro- and magnetoencephalography in human participants who received auditory stimulation across sleep stages. We conducted a series of analyses that test different models of pathways through which CLAS of slow oscillations may affect widespread neural activity that have been suggested in literature, using spatial information, timing and phase relationships in the source-localized magnetoencephalography data. The results suggest that auditory information reaches ventral frontal lobe areas via non-lemniscal pathways. From there, a slow oscillation is created and propagated. We demonstrate that while the state of excitability of tissue in auditory cortex and frontal ventral regions shows some synchrony with the electroencephalography (EEG)-recorded up-states that are commonly used for CLAS, it is the state of ventral frontal regions that is most critical for slow oscillation generation. Our findings advance models of how CLAS leads to enhancement of slow oscillations, sleep spindles and associated cognitive benefits and offer insight into how the effectiveness of brain stimulation techniques can be improved.

Conversation disruptions in early childhood predict executive functioning development: A longitudinal study.

Conversational turn-taking is a complex communicative skill that requires both linguistic and executive functioning (EF) skills, including processing input while simultaneously forming and inhibiting responses until one's turn. Adult-child turn-taking predicts children's linguistic, cognitive, and socioemotional development. However, little is understood about how disruptions to temporal contingency in turn-taking, such as interruptions and overlapping speech, relate to cognitive outcomes, and how these relationships may vary across developmental contexts. In a longitudinal sample of 275 socioeconomically diverse mother-child dyads (children 50% male, 65% White), we conducted pre-registered examinations of whether the frequency of dyads' conversational disruption during free play when children were 3 years old related to children's executive functioning (EF; 9 months later), self-regulation skills (18 months later), and externalizing psychopathology in early adolescence (age 10-12 years). Contrary to hypotheses, more conversational disruptions significantly predicted higher inhibition skills, controlling for sex, age, income-to-needs (ITN), and language ability. Results were driven by maternal disruptions of the child's speech, and could not be explained by measures of overall talkativeness or interactiveness. Exploratory analyses revealed that ITN moderated these relationships, such that the positive effect of disruptions on inhibition was strongest for children from lower ITN backgrounds. We discuss how adult-driven "cooperative overlap" may serve as a form of engaged participation that supports cognition and behavior in certain cultural contexts.

Early gesture use predicts children's language development in South Korea: New evidence supporting the cross-cultural importance of pointing.

Research in the U.S. and other Western countries shows that children's early gesture use, which starts prior to verbal communication, is an important predictor of children's later language development. Despite increasing efforts to study gesture use in diverse contexts, most of our knowledge on the role of gesture is largely based on populations of Western countries. In this study, we add to the growing body of international research by examining gesture use by 31 mothers and their 14-month-old infants (12 girls) in South Korea and investigate the gestures used during interaction, and whether early gesture use at 14 months predicts Korean children's later language skills at 36 months. The results showed that in addition to using gestures observed in other cultural contexts, Korean mother-child dyads used culturally specific gesture (i.e., bowing), showing an early sign of socialization that starts with preverbal children. In addition, Korean infants' index-finger pointing, but not showing and giving, predicted their later receptive and expressive vocabulary skills at 36 months, providing additional support for the importance of pointing in early language development.

Comparing apples to manzanas and oranges to naranjas: A new measure of English-Spanish vocabulary for dual language learners.

The valid assessment of vocabulary development in dual-language-learning infants is critical to developmental science. We developed the Dual Language Learners English-Spanish (DLL-ES) Inventories to measure vocabularies of U.S. English-Spanish DLLs. The inventories provide translation equivalents for all Spanish and English items on Communicative Development Inventory (CDI) short forms; extended inventories based on CDI long forms; and Spanish language-variety options. Item-Response Theory analyses applied to Wordbank and Web-CDI data (n = 2603, 12-18 months; n = 6722, 16-36 months; half female; 1% Asian, 3% Black, 2% Hispanic, 30% White, 64% unknown) showed near-perfect associations between DLL-ES and CDI long-form scores. Interviews with 10 Hispanic mothers of 18- to 24-month-olds (2 White, 1 Black, 7 multi-racial; 6 female) provide a proof of concept for the value of the DLL-ES for assessing the vocabularies of DLLs.

Chinese parents' support of preschoolers' mathematical development.

Research has documented the critical role played by the early home environment in children's mathematical development in Western contexts. Yet little is known about how Chinese parents support their preschoolers' development of math skills. The Chinese context is of particular interest because Chinese children outperform their Western counterparts in math, even early in development. The current study sought to fill this gap by examining a sample of 90 families of 4- and 5-year-olds from mainland China. Parental support-as measured by the frequency of parent-child engagement in home activities as well as parent number talk-and parents' role in children's numeracy skills were investigated. Results indicate wide variation among parents in both types of support. Frequency of engagement in formal numeracy activities, including counting objects and reading number story books, was related to children's knowledge of cardinality. A principal components analysis did not identify informal numeracy activities as a distinct home activity component, likely due to the infrequent occurrences of game-like numeracy activities among the Chinese families. Instead, a structured activity component emerged (e.g., playing musical instruments) and was positively related to children's arithmetic skills. Diversity, but not quantity, of parent number talk was related to children's symbolic magnitude understanding. The distinctive relationships between specific parental measures and child outcomes speak to the need for nuanced identification of home environment factors that are beneficial to particular math competencies. The findings also suggest cultural variations in the mechanisms that support children's mathematical development, highlighting the merits of investigating this topic in non-Western contexts.

Parents' talk about conceptual categories with infants: stability, variability, and implications for expressive language development.

Children's exposure to talk about conceptual categories plays a powerful role in shaping their conceptual development. However, it remains unclear when parents begin to talk about categories with young children and whether such talk relates to children's language skills. This study examines relations between parents' talk about conceptual categories and infants' expressive language development. Forty-seven parent-infant dyads were videotaped playing together at child age 10, 12, 14, and 16 months. Transcripts of interactions were analyzed to identify parents' talk about conceptual categories. Children's expressive language development was assessed at 18 months. Findings indicate that parents indeed talked about conceptual categories with infants and that talk was stable across time, with college-educated parents producing more than non-college-educated parents. Further, parents' talk about conceptual categories between 10 and 16 months predicted children's 18-month expressive language. This study sheds new light on mechanisms through which early experiences may support children's language development.

"Mom said it in quotation marks!" Irony comprehension and metapragmatic awareness in 8-year-olds.

This study investigated links between the development of children's understanding of ironic comments and their metapragmatic knowledge. Forty-six 8-year-olds completed the short version of the Irony Comprehension Task, during which they were presented with ironic comments in three stories and asked to provide reasons for why the speaker in a story uttered an ironic comment. We coded their responses and compared the results to similar data collected previously with 5-year-olds. Results showed that compared to younger children, 8-year-olds frequently refer to interlocutors' emotions, intentions, and to metapragmatics. These results support the view that comprehension of verbal irony is an emerging skill in children.

Exploring the Linguistic, Cognitive, and Social Skills Underlying Lexical Processing Efficiency as Measured by the Looking-while-Listening Paradigm.

The looking-while-listening (LWL) paradigm is frequently used to measure toddlers' lexical processing efficiency (LPE). Children's LPE is associated with vocabulary size, yet other linguistic, cognitive, or social skills contributing to LPE are not well understood. It also remains unclear whether LPE measures from two types of LWL trials (target-initial versus distractor-initial trials) are differentially associated with the abovementioned potential correlates of LPE. We tested 18- to 24-month-olds and found that children's word learning on a fast-mapping task was associated with LPE measures from all trials and distractor-initial trials but not target-initial trials. Children's vocabulary and pragmatic skills were both associated with their fast-mapping performance. Executive functions and pragmatic skills were associated with LPE measures from distractor-initial but not target-initial trials. Hence, LPE as measured by the LWL paradigm may reflect a constellation of skills important to language development. Methodological implications for future studies using the LWL paradigm are discussed.

A parent gesture intervention as a means to increase parent declarative pointing and child vocabulary.

This study examined whether a brief parent gesture training resulted in a change in the communicative intent of pointing gestures used by parents of infants from age 10-12 months and whether specific types of points (declarative vs. imperative) were more or less likely to predict later child language skill at 18 months. Compared to parents who were randomized to the control group, parents in the intervention group produced significantly more declarative pointing gestures as a result of the intervention. Moreover, parents' use of declarative points at 12 months was predictive of later child vocabulary comprehension at 18 months. These findings suggest that a short-term parent training can have important effects on the communicative intentions conveyed through gesture which predict vocabulary development.

An intervention to increase conversational turns between parents and young children.

Behavioral and neural evidence indicates that young children who engage in more conversations with their parents have better later language skills such as vocabulary and academic language abilities. Previous studies find that the extent to which parents engage in conversational turn-taking with children varies considerably. How, then, can we promote extended conversations between parents and their children? Instead of asking parents to engage in longer turn-taking episodes, we provided parents with information on conversational content that we hypothesized would lead to increased episodes of longer, more sustained conversational turn-taking. Specifically, we found that boosting the frequency of parent-child talk about abstract, non-present concepts - decontextualized language - led to an increase in dyadic conversational turn-taking during home mealtimes several weeks later.

Young children communicate their ignorance and ask questions.

Children acquire information, especially about the culture in which they are being raised, by listening to other people. Recent evidence has shown that young children are selective learners who preferentially accept information, especially from informants who are likely to be representative of the surrounding culture. However, the extent to which children understand this process of information transmission and actively exploit it to fill gaps in their knowledge has not been systematically investigated. We review evidence that toddlers exhibit various expressive behaviors when faced with knowledge gaps. They look toward an available adult, convey ignorance via nonverbal gestures (flips/shrugs), and increasingly produce verbal acknowledgments of ignorance ("I don't know"). They also produce comments and questions about what their interlocutors might know and adopt an interrogative stance toward them. Thus, in the second and third years, children actively seek information from interlocutors via nonverbal gestures or verbal questions and display a heightened tendency to encode and retain such sought-after information.

Analyzing input quality along three dimensions: interactive, linguistic, and conceptual.

This paper provides an overview of the features of caregiver input that facilitate language learning across early childhood. We discuss three dimensions of input quality: interactive, linguistic, and conceptual. All three types of input features have been shown to predict children's language learning, though perhaps through somewhat different mechanisms. We argue that input best designed to promote language learning is interactionally supportive, linguistically adapted, and conceptually challenging for the child's age/level. Furthermore, input features interact across dimensions to promote learning. Some but not all qualities of input vary based on parent socioeconomic status, language, or culture, and contexts such as book-reading or pretend play generate uniquely facilitative input features. The review confirms that we know a great deal about the role of input quality in promoting children's development, but that there is much more to learn. Future research should examine input features across the boundaries of the dimensions distinguished here.

Language Exposure Relates to Structural Neural Connectivity in Childhood.

Neuroscience research has elucidated broad relationships between socioeconomic status (SES) and young children's brain structure, but there is little mechanistic knowledge about specific environmental factors that are associated with specific variation in brain structure. One environmental factor, early language exposure, predicts children's linguistic and cognitive skills and later academic achievement, but how language exposure relates to neuroanatomy is unknown. By measuring the real-world language exposure of young children (ages 4-6 years, 27 male/13 female), we confirmed the preregistered hypothesis that greater adult-child conversational experience, independent of SES and the sheer amount of adult speech, is related to stronger, more coherent white matter connectivity in the left arcuate and superior longitudinal fasciculi on average, and specifically near their anterior termination at Broca's area in left inferior frontal cortex. Fractional anisotropy of significant tract subregions mediated the relationship between conversational turns and children's language skills and indicated a neuroanatomical mechanism underlying the SES "language gap." Post hoc whole-brain analyses revealed that language exposure was not related to any other white matter tracts, indicating the specificity of this relationship. Results suggest that the development of dorsal language tracts is environmentally influenced, specifically by early, dialogic interaction. Furthermore, these findings raise the possibility that early intervention programs aiming to ameliorate disadvantages in development due to family SES may focus on increasing children's conversational exposure to capitalize on the early neural plasticity underlying cognitive development.SIGNIFICANCE STATEMENT Over the last decade, cognitive neuroscience has highlighted the detrimental impact of disadvantaged backgrounds on young children's brain structure. However, to intervene effectively, we must know which proximal aspects of the environmental aspects are most strongly related to neural development. The present study finds that young children's real-world language exposure, and specifically the amount of adult-child conversation, correlates with the strength of connectivity in the left hemisphere white matter pathway connecting two canonical language regions, independent of socioeconomic status and the sheer volume of adult speech. These findings suggest that early intervention programs aiming to close the achievement gap may focus on increasing children's conversational exposure to capitalize on the early neural plasticity underlying cognitive development.

A parent intervention with a growth mindset approach improves children's early gesture and vocabulary development.

Socioeconomic disparities in children's early vocabulary skills can be traced back to disparities in gesture use at age one and are due, in part, to the quantity and quality of communication children are exposed to by parents. Further, parents' mindsets about intelligence contribute to their interactions with their children. We implemented a parent gesture intervention with a growth mindset component with 47 parents of 10-month-olds to determine whether this approach would increase parents' use of the pointing gesture, infants' use of pointing, and child vocabulary growth. The intervention had an effect on parent gesture such that by child age 12-months, parents who received the intervention increased in their pointing more than parents in the control condition. Importantly, the intervention also had a significant effect on child gesture use with parents. There was no main effect of the intervention on child vocabulary. Further, the effect of the intervention on pointing was stronger for parents who endorsed fixed mindsets at baseline, and had an added benefit of increased vocabulary growth from 10-18 months for children of those parents who endorsed fixed mindsets. Incorporating growth mindset approaches into parenting interventions is encouraged.

Children's Early Decontextualized Talk Predicts Academic Language Proficiency in Midadolescence.

This study examines whether children's decontextualized talk-talk about nonpresent events, explanations, or pretend-at 30 months predicts seventh-grade academic language proficiency (age 12). Academic language (AL) refers to the language of school texts. AL proficiency has been identified as an important predictor of adolescent text comprehension. Yet research on precursors to AL proficiency is scarce. Child decontextualized talk is known to be a predictor of early discourse development, but its relation to later language outcomes remains unclear. Forty-two children and their caregivers participated in this study. The proportion of child talk that was decontextualized emerged as a significant predictor of seventh-grade AL proficiency, even after controlling for socioeconomic status, parent decontextualized talk, child total words, child vocabulary, and child syntactic comprehension.

Language Matters: Denying the Existence of the 30-Million-Word Gap Has Serious Consequences.

Sperry, Sperry, and Miller (2018) aim to debunk what is called the 30-million-word gap by claiming that children from lower income households hear more speech than Hart and Risley () reported. We address why the 30-million-word gap should not be abandoned, and the importance of retaining focus on the vital ingredient to language learning-quality speech directed to children rather than overheard speech, the focus of Sperry et al.'s argument. Three issues are addressed: Whether there is a language gap; the characteristics of speech that promote language development; and the importance of language in school achievement. There are serious risks to claims that low-income children, on average, hear sufficient, high-quality language relative to peers from higher income homes.

Teaching a novel word: Parenting styles and toddlers' word learning.

We examined the styles that parents adopted while teaching a novel word to their toddlers and whether those styles related to children's word learning and engagement during the task. Participants were 36 parents and their toddlers (Mage = 20 months). Parents were videotaped while teaching their children a name for a novel object. Parental utterances were transcribed verbatim and coded for cognitive and autonomy support. Children's utterances were coded for elicited and spontaneous contributions. Children's ability to recognize and process the novel word was assessed using the Looking-While-Listening task. Two parental cognitive support styles were identified via cluster analysis: "Cognitive Scaffolders," who combined a diversity of teaching moves, and "Labelers," who focused on labeling the novel object for the children. Similarly, two parental autonomy support styles were identified: "Followers," who focused on following the children's lead and providing positive feedback, and "Non-followers," who used diverse communicative ways to engage the children. Compared with parents who were Labelers, parents who were Cognitive Scaffolders were not more or less likely to be Followers. Children of Cognitive Scaffolders were better at recognizing the novel word, and children of Followers were more engaged (provided more elicited and spontaneous contributions) in the word-teaching task. Children's ability to recognize the novel word was not related to their engagement. Findings highlight the unique contributions of parental cognitive and autonomy support to children's word learning and engagement.

Conversation about the future self improves preschoolers' prospection abilities.

Prospection, the ability to engage in future-oriented thinking and decision making, begins to develop during the preschool years yet remains far from adult-like. One specific challenge for children of this age is with regard to thinking and reasoning about their future selves. Drawing from work indicating the importance of adult-child conversation in language and cognitive development, the current study examined the extent to which conversations about the future and the self may facilitate preschool-aged children's prospective thinking. The participants, 4- and 5-year-old children (N = 68), were randomly assigned to read books surrounding one of four topics with an adult experimenter: their present self, their future self, another child's present self, or another child's future self. Children whose conversations were centered on their future selves outperformed other children in the sample on a battery of prospection assessments taken immediately after the manipulation. Of the three prospection assessments administered, the manipulation had the strongest effect on children's prospective memories. Results are discussed in terms of the role that everyday conversation can play in fostering children's cognitive development during the early childhood years.

Beyond the 30-Million-Word Gap: Children's Conversational Exposure Is Associated With Language-Related Brain Function.

Children's early language exposure impacts their later linguistic skills, cognitive abilities, and academic achievement, and large disparities in language exposure are associated with family socioeconomic status (SES). However, there is little evidence about the neural mechanisms underlying the relation between language experience and linguistic and cognitive development. Here, language experience was measured from home audio recordings of 36 SES-diverse 4- to 6-year-old children. During a story-listening functional MRI task, children who had experienced more conversational turns with adults-independently of SES, IQ, and adult-child utterances alone-exhibited greater left inferior frontal (Broca's area) activation, which significantly explained the relation between children's language exposure and verbal skill. This is the first evidence directly relating children's language environments with neural language processing, specifying both an environmental and a neural mechanism underlying SES disparities in children's language skills. Furthermore, results suggest that conversational experience impacts neural language processing over and above SES or the sheer quantity of words heard.

Fathers' repetition of words is coupled with children's vocabularies.

Differences in vocabulary size among children can be explained in part by differences in parents' language input, but features of caregivers' input can be more or less beneficial depending on children's language abilities. The current study focused on a specific feature of infant-directed speech: parents' repetition of words across utterances. Although previous work with infants showed a positive relation between repetition and children's vocabulary, we predicted that this would not be the case later in development. Instead, parents may use less repetition as their children become increasingly proficient language learners. In the current study, we examined the extent to which low-income fathers of 24-month-olds (N=41) repeat words to their children using three indices: type-token ratio, automated repetition index, and partial repetition of open-class words. The same finding emerged across all measures of repetition: Fathers whose children had larger vocabularies at 24months repeated wordslessoften, suggesting a developmental coupling of fathers' input and children's language proficiency.