Sleep-dependent memory consolidation of televised content in infants.

Infants face the constant challenge of selecting information for encoding and storage from a continuous incoming stream of data. Sleep might help in this process by selectively consolidating new memory traces that are likely to be of future relevance. Using a deferred imitation paradigm and an experimental design, we asked whether 15- and 24-month-old infants (N = 105) who slept soon after encoding a televised demonstration of target actions would show higher imitation scores (retention) after a 24-h delay than same-aged infants who stayed awake for ≥4 h after encoding. In light of infants' well-known difficulties in learning and remembering information from screens, we tested if increasing the relevance of the televised content via standardised caregiver verbalisations might yield the highest imitation scores in the sleep condition. Regardless of sleep condition, 24-month-olds exhibited retention of target actions while 15-month-olds consistently failed to do so. For 24-month-olds, temporal recall was facilitated by sleep, but not by parental verbalisations. Correlational analyses revealed that more time asleep within 4 h after encoding was associated with better retention of the target actions and their temporal order in 24-months-olds. These results suggest that sleep facilitates memory consolidation of screen-based content in late infancy and that this effect might not hinge on caregivers' verbal engagement during viewing.

Quality of Mother-Child Interaction Before, During, and After Smartphone Use.

Studies have demonstrated that parents often exhibit a still face while silently reading their cell phones when responding to texts. Such disruptions to parent-child interactions have been observed during parental media use such as texting and these disruptions have been termed technoference. In the present study, we explored changes to mother-child interactions that occur before, during and after interruptions due to texting using an adapted naturalistic still face paradigm. Specifically, we examined the effect of an interruption due to either maternal smartphone use or use of an analog medium on maternal interaction quality with their 20- to 22-month-old children. Mother-child interactions during free play were interrupted for 2 min by asking the mothers to fill out a questionnaire either (a) by typing on the smartphone (smartphone group) or (b) on paper with a pen (paper-pencil group). Interactional quality was compared between free-play and interruption phases and to a no-interruption control group. Mixed ANOVA across phase and condition indicated that maternal responsiveness and pedagogical behavior decreased during the interruption phase for both the interruption groups (smartphone and paper-and-pencil) but not for the no-interruption group. Children also increased their positive bids for attention during the paper-and-pencil and the smartphone conditions relative to the no-interruption control. These findings are consistent with a large body of research on the still-face paradigm and with a recent study demonstrating that smartphone interruptions decreased parenting quality. The present study, however, connects these lines of research showing the many everyday disruptions to parent-child interactions are likely to decrease parenting quality and that toddlers are likely to detect and attempt to repair such interruptions.

The effect of napping and nighttime sleep on memory in infants.

During the first year of life, infants devote the majority of their time to sleep. Research in adults has shown that sleep supports a variety of memory processes. Surprisingly, sleep's function for infant memory has only started to receive attention in research. In this chapter, we will describe age-related changes in sleep and in memory processing over the first years of life, as well as methods to capture both sleep and memory. Then, we will review current findings on the effects of sleep on memory processing in infants. Lastly, we will also point out gaps in current knowledge and describe potential avenues for future research. Overall, the results of recent experimental studies provide evidence that timely, extended napping is involved in how memories are encoded and stored in the long-term and contribute to the formation of knowledge networks in infants.

Does texting interrupt imitation learning in 19-month-old infants?

Observed disruptions to parent-child interactions during parental media use, such as texting, have been termed technoference. For example, when a language learning interaction was disrupted by a phone call, toddlers were less likely to acquire the word. Other studies demonstrated that parents often exhibit a still face while silently reading information on their cell phones. In the present study, the effect of a text interruption on infant imitation learning was examined. Parents demonstrated three target actions to their infants and then infants were given the opportunity to repeat those interactions. The actions were demonstrated four times. Text interruptions occurred before or between demonstrations. Performance of these groups was compared to a baseline control group where the infant did not see a demonstration of the target actions and a no-interruption group where the parents demonstrated the target actions four times without interruption. Parents were randomly assigned to three conditions, interruption-first condition, one-interruption condition, or three-interruptions condition. Infant behavior was measured during the interruptions. Across text interruption groups parents exhibited high levels of still face during the interruptions (77 %). However, infants in all 3 interruption groups performed significantly above the baseline control indicating learning despite the interruptions. Higher reported maternal reliance on the smartphone was related to poorer imitation performance overall. In contrast, when parents reported that they found it easier to multi-task infant imitation rates were higher. These findings indicate that infants can learn under conditions of brief technoference and that individual differences in family media ecology are associated with learning.

State-Dependent Memory in Infants.

Why do infants remember some things and not others? Human infants frequently cycle through different states such as calm attentiveness, wakeful activity, and crying. Given that cognitive processes do not occur in isolation, such fluctuations in internal state might influence memory processing. In the present experiment, declarative memory in 9-month-old infants (N = 96) was heavily state dependent. Infants exhibited excellent retention of a deferred imitation task after a 15-min delay if their state at encoding was identical to their state at retrieval (e.g., calm). Infants failed to exhibit retention if their state at encoding was different from their state at retrieval (e.g., calm vs. animated). Infant memory processing depends on internal cues.

A New 3-Day Standardized Eyeblink Conditioning Protocol to Assess Extinction Learning From Infancy to Adulthood.

Associative learning can be observed from the neonatal period onward, providing opportunities to examine changes in basic learning and memory abilities. One method that is suitable to study associative learning is classical eyeblink conditioning (EBC) which is dependent on the cerebellum. Extinction learning can be systematically investigated in this paradigm by varying the context during learning and extinction. Because of methodological difficulties and ethical challenges, no studies have compared extinction learning using EBC across human development. Our goal was to test feasibility of a 3-day delay EBC paradigm that can be used from infancy to adulthood. Acceptance/safety was tested especially for infancy by investigating attrition rates and parental report on infant wellbeing. On a paradigm side, we tested if the paradigm leads to successful acquisition and extinction. An air puff served as unconditional stimulus (US) and a tone as conditional stimulus (CS). On day 1 during acquisition, participants received 36 US-CS pairings in context A. On day 2, participants received 12 acquisition trials in context A to consolidate association learning, followed by 48 extinction trials (tone alone presentations) in context B. Renewal was assessed on day 3 and incorporated 12 CS alone trials presented in both the acquisition context and the extinction context. Eyeblink responses were videotaped and coded offline. The protocol was tested with 12-36-months-old infants (N = 72), adolescents (N = 8), and adults (N = 8). Concerning the acceptance/safety side, attrition ranged from 21 to 58% in infant samples due to the complex preparation of the children for the paradigm. However, attrition is equal to or lower than other infant learning paradigms. Parents of infant samples were very interested in the paradigm and reported low levels of infant stress, exhaustion, and negative feelings during the sessions. Data quality was very high, and no participant had to be excluded because of insufficient data. Concerning the paradigm side, participants showed successful acquisition and extinction as a group. The procedure is ethically sound, feasible, tolerated by many infants, and acceptable among parents. The data show successful acquisition and extinction rates, making the paradigm a valuable tool for investigating developmental changes in extinction learning over the lifespan.

Beyond Screen Time: A Synergistic Approach to a More Comprehensive Assessment of Family Media Exposure During Early Childhood.

Digital media availability has surged over the past decade. Because of a lack of comprehensive measurement tools, this rapid growth in access to digital media is accompanied by a scarcity of research examining the family media context and sociocognitive outcomes. There is also little cross-cultural research in families with young children. Modern media are mobile, interactive, and often short in duration, making them difficult to remember when caregivers respond to surveys about media use. The Comprehensive Assessment of Family Media Exposure (CAFE) Consortium has developed a novel tool to measure household media use through a web-based questionnaire, time-use diary, and passive-sensing app installed on family mobile devices. The goal of developing a comprehensive assessment of family media exposure was to take into account the contextual factors of media use and improve upon the limitations of existing self-report measures, while creating a consistent, scalable, and cost-effective tool. The CAFE tool captures the content and context of early media exposure and addresses the limitations of prior media measurement approaches. Preliminary data collected using this measure have been integrated into a shared visualization platform. In this perspective article, we take a tools-of-the-trade approach (Oakes, 2010) to describe four challenges associated with measuring household media exposure in families with young children: measuring attitudes and practices; capturing content and context; measuring short bursts of mobile device usage; and integrating data to capture the complexity of household media usage. We illustrate how each of these challenges can be addressed with preliminary data collected with the CAFE tool and visualized on our dashboard. We conclude with future directions including plans to test reliability, validity, and generalizability of these measures.

Sleep-dependent selective imitation in infants.

In adults, sleep selectively consolidates those memories that are relevant for future events. The present study tested whether napping after encoding plays a role in selective memory consolidation in infants. Infants aged 15 and 24 months (n = 48 per age) were randomly assigned to a nap or a no-nap demonstration condition, or a baseline control condition. In the demonstration conditions, infants observed an experimenter perform an irrelevant action followed by a relevant action to achieve a desirable outcome on four different toys. Infant imitation of irrelevant and relevant actions was coded at a test session that occurred after a 24-hr delay. The demonstration and test sessions were scheduled around infants' naturally occurring sleeping patterns. When order of actions was not taken into account, infants in both demonstration conditions exhibited retention of the relevant and irrelevant target actions. Contrary to expectations, infants in the nap condition did not perform the relevant action only more often than infants in the no-nap condition. As expected, only infants in the no-nap condition faithfully reproduced the two actions in the demonstrated order: irrelevant action first, followed by the relevant action. Thus, sleep might help infants to selectively "discard" aspects of a learning experience that they identify as being not useful or relevant in the future.

Gist extraction and sleep in 12-month-old infants.

Gist extraction is the process of excerpting shared features from a pool of new items. The present study examined sleep and the consolidation of gist in 12-month-old infants using a deferred imitation paradigm. Sixty infants were randomly assigned to a nap, a no-nap or a baseline control condition. In the nap and no-nap conditions, infants watched demonstrations of the same target actions on three different hand puppets that shared some features. During a 4-h delay, infants in the nap condition took a naturally scheduled nap while infants in the no-nap condition naturally stayed awake. Afterwards, infants were exposed to a novel forth hand puppet that combined some of the features from the previously encountered puppets. Only those infants who took a nap after learning produced a significantly higher number of target actions than infants in the baseline control condition who had not seen any demonstrations of target actions. Infants in the nap condition also produced significantly more target actions than infants in the no-nap condition. Sleep appears to support the storage of gist, which aids infants in applying recently acquired knowledge to novel circumstances.

Naps promote flexible memory retrieval in 12-month-old infants.

Flexibility in applying existing knowledge to similar cues is a corner stone of memory development in infants. Here, we examine the effect of sleep on the flexibility of memory retrieval using a deferred imitation paradigm. Forty-eight 12-month-old infants were randomly assigned to either a nap or a no-nap demonstration condition (scheduled around their natural daytime sleep schedule) or to a baseline control condition. In the demonstration conditions, infants watched an experimenter perform three target actions on a hand puppet. Immediately afterwards, infants were allowed to practice the target actions three times. In a test session 4-hr later, infants were given the opportunity to reproduce the actions with a novel hand puppet differing in color from the puppet used during the demonstration session. Only infants in the nap-condition performed significantly more target actions than infants in the baseline control condition. Furthermore, they were faster to carry out the first target action than infants in the no-nap condition. We conclude that sleep had a facilitative effect on infants' flexibility of memory retrieval.

The relationship between prior night's sleep and measures of infant imitation.

We examined whether sleep quality during the night and naps during the day preceding a learning event are related to memory encoding in human infants. Twenty-four 6- and twenty-four 12-month-old infants' natural sleeping behavior was monitored for 24 hr using actigraphy. After the recording period, encoding was assessed using an imitation paradigm. In an initial baseline phase, infants were allowed to interact with the stimulus to assess spontaneous production of any target actions. Infants then watched an experimenter demonstrate a sequence of three target actions and were immediately given the opportunity to reproduce the demonstrated target actions to assess memory encoding. Analyses revealed significant correlations between nighttime sleep quality variables (sleep efficiency, sleep fragmentation) and immediate imitation in 6-month-olds, but not in 12-month-olds. High sleep quality in the preceding night was thus positively associated with next day's memory encoding in 6-month-old infants.

Timely sleep facilitates declarative memory consolidation in infants.

Human infants devote the majority of their time to sleeping. However, very little is known about the role of sleep in early memory processing. Here we test 6- and 12-mo-old infants' declarative memory for novel actions after a 4-h [Experiment (Exp.) 1] and 24-h delay (Exp. 2). Infants in a nap condition took an extended nap (≥30 min) within 4 h after learning, whereas infants in a no-nap condition did not. A comparison with age-matched control groups revealed that after both delays, only infants who had napped after learning remembered the target actions at the test. Additionally, after the 24-h delay, memory performance of infants in the nap condition was significantly higher than that of infants in the no-nap condition. This is the first experimental evidence to our knowledge for an enhancing role of sleep in the consolidation of declarative memories in the first year of life.

Contribution of cyclooxygenase-1 to thromboxane formation, platelet-vessel wall interactions and atherosclerosis in the ApoE null mouse.

OBJECTIVE: Prostaglandin and thromboxane (TXA(2)) generation is increased in atherosclerosis. Studies with selective inhibitors attribute the enhanced prostacyclin (PGI(2)) generation to both cyclooxygenase-1 (COX-1) and COX-2 whereas the increased TXA(2) generation reflects platelet COX-1 expression. However, TXA(2) formation remains elevated in patients with cardiovascular disease on doses of aspirin that fully suppress platelet COX-1, suggesting other tissue sources for TXA(2) formation. Disruption of the thromboxane receptor gene suppresses the development of atherosclerosis. Notwithstanding this, the role of COX-1 in atherosclerosis is unclear, as it is widely distributed and contributes to a number of products, including those that potentially contribute to the resolution of inflammation. METHODS AND RESULTS: We examined the role of COX-1 on prostaglandin generation, development of atherosclerosis and platelet-vessel wall interactions in the apoE(-/-) murine model by disrupting the COX-1 gene. ApoE(-/-)/COX-1(+/+), ApoE(-/-)/COX-1(+/-) and ApoE(-/-)/COX-1(-/-), were administered a 1% cholesterol diet for 8 weeks. Stable urinary metabolites of PGI(2) and TXA(2), which were markedly increased in the ApoE(-/-)/COX-1(+/+) were reduced by disruption of COX-1. Deletion of one or both copies of the COX-1 gene suppressed lesion formation. Assessment of platelet-vessel wall interactions by intravital microscopy showed a significant decrease in firm adhesion of platelets in the apoE/COX-1 double knockout (DKO). CONCLUSION: COX-1 contributes to the enhanced formation of both PGI(2) and TXA(2) in atherosclerosis, and to the development of the disease. Non-platelet sources of COX-1 and TXA(2) that are inaccessible to standard doses of aspirin may contribute to the development of atherosclerosis.