Developmental Changes in the Relative Weighting of Geometric and Experience-Dependent Location Cues

This article introduces a promising new methodology called optical imaging. Optical imaging is used for measuring changes in cortical blood flow due to functional activation. The article outlines the pros and cons of using optical imaging for studying the brain correlates of perceptual, cognitive, and language development in infants and young children.     

Cerebral palsy in very preterm infants: new epidemiological insights

The focus of this review is on new insights from recent epidemiological research on cerebral palsy in preterm infants. These include: 1) a better understanding of issues related to diagnosis and classification; 2) new information about the brain abnormalities underlying cerebral palsy in preterm infants; and 3) a better understanding of biological mechanisms that may underlie previously described epidemiological associations. Ongoing efforts to improve the diagnosis and classification of cerebral palsy have been enhanced by findings from serial examinations of cohorts of very preterm infants. Cranial ultrasonography through the anterior fontanelle of very preterm infants has provided information about grossly evident brain damage, found in about one-half of preterm infants who develop cerebral palsy. Insights into the pathophysiologic basis for certain epidemiologic associations have come from studies of experimental brain damage in animals and clinical studies of neurologic disorders in adults. Much of the current epidemiological research into the causes of cerebral palsy in preterm infants has focused on two potential mechanisms of brain damage. One mechanism involves insufficient cerebral perfusion; the other, cytokine-mediated damage, potentially triggered by events such as maternal infection (e.g., intrauterine or periodontal infection), neonatal infection (e.g., sepsis and necrotizing enterocolitis), and neonatal oxygen- or ventilator-induced lung injury. In addition to the preterm infant's increased exposure to such damaging factors, the high frequency of cerebral palsy in these infants might be due, in part, to insufficient levels of developmentally regulated protective substances, such as thyroid hormone and glucocorticoids. Models of causation currently are being investigated using recently developed methods for quantifying, with small quantities of blood, biomolecules that are suspected to either promote or protect against brain damage in the neonate. Clinical investigations now under way can be expected to identify strategies to be tested in clinical trials that could lower the risk of cerebral palsy in very preterm infants.     

Neurophysiologic evaluation of early cognitive development in high-risk infants and toddlers

New knowledge of the perceptual, discriminative, and memory capabilities of very young infants has opened the door to further evaluation of these abilities in infants who have risk factors for cognitive impairments. A neurophysiologic technique that has been very useful in this regard is the recording of event-related potentials (ERPs). The event-related potential (ERP) technique is widely used by cognitive neuroscientists to study cognitive abilities such as discrimination, attention, and memory. This method has many attractive attributes for use in infants and children as it is relatively inexpensive, does not require sedation, has excellent temporal resolution, and can be used to evaluate early cognitive development in preverbal infants with limited behavioral repertories. In healthy infants and children, ERPs have been used to gain a further understanding of early cognitive development and the effect of experience on brain function. Recently, ERPs have been used to elucidate atypical memory development in infants of diabetic mothers, difficulties with perception and discrimination of speech sounds in infants at risk for dyslexia, and multiple areas of cognitive differences in extremely premature infants. Atypical findings seen in high-risk infants have correlated with later cognitive outcomes, but the sensitivity and specificity of the technique has not been studied, and thus evaluation of individual infants is not possible at this time. With further research, this technique may be very useful in identifying children with cognitive deficits during infancy. Because even young infants can be examined with ERPs, this technique is likely to be helpful in the development of focused early intervention programs used to improve cognitive function in high-risk infants and toddlers.     

Preparing for the 21st Century: Some Goals and Challenges for Studies of Infant Sensory and Perceptual Development

While acknowledging that there has been enormous progress in our understanding of sensory and perceptual development in human infancy over the past three decades, this paper looks toward future directions in preparation for the 21st century. It is argued that investigators should move away from the categorical thinking that dominates the field and focus more on developmental process in studying the acquisition of perceptual skills. Also, more attention should be paid to the functional role of perceptual skills and less to demonstrations of discrimination. In addition, researchers should attempt to bring their work and conceptualizations more in line with that on adults and older children. Future work on sensory and perceptual development in infancy will be heavily influenced by our understanding of how the brain works, especially with refinements in brain imaging and neurophysiology and with developments in computational modeling of perceptual processes. Finally, it is likely that there will be increased application of research findings to such problems as identification of infants at risk.     

Infants' knowledge of objects: beyond object files and object tracking

Two independent research communities have produced large bodies of data concerning object representations: the community concerned with the infant's object concept and the community concerned with adult object-based attention. We marshal evidence in support of the hypothesis that both communities have been studying the same natural kind. The discovery that the object representations of young infants are the same as the object files of mid-level visual cognition has implications for both fields.     

Parsing eye-tracking data of variable quality to provide accurate fixation duration estimates in infants and adults

Researchers studying infants’ spontaneous allocation of attention have traditionally relied on hand-coding infants’ direction of gaze from videos; these techniques have low temporal and spatial resolution and are labor intensive. Eye-tracking technology potentially allows for much more precise measurement of how attention is allocated at the subsecond scale, but a number of technical and methodological issues have given rise to caution about the quality and reliability of high temporal resolution data obtained from infants. We present analyses suggesting that when standard dispersal-based fixation detection algorithms are used to parse eye-tracking data obtained from infants, the results appear to be heavily influenced by interindividual variations in data quality. We discuss the causes of these artifacts, including fragmentary fixations arising from flickery or unreliable contact with the eyetracker and variable degrees of imprecision in reported position of gaze. We also present new algorithms designed to cope with these problems by including a number of new post hoc verification checks to identify and eliminate fixations that may be artifactual. We assess the results of our algorithms by testing their reliability using a variety of methods and on several data sets. We contend that, with appropriate data analysis methods, fixation duration can be a reliable and stable measure in infants. We conclude by discussing ways in which studying fixation durations during unconstrained orienting may offer insights into the relationship between attention and learning in naturalistic settings.     

Electrophysiological evidence for the understanding of maternal speech by 9-month-old infants

Early word learning in infants relies on statistical, prosodic, and social cues that support speech segmentation and the attachment of meaning to words. It is debated whether such early word knowledge represents mere associations between sound patterns and visual object features, or reflects referential understanding of words. By measuring an event-related brain potential component known as the N400, we demonstrated that 9-month-old infants can detect the mismatch between an object appearing from behind an occluder and a preceding label with which their mother introduces it. Differential N400 amplitudes have been shown to reflect semantic priming in adults, and its absence in infants has been interpreted as a sign of associative word learning. By setting up a live communicative situation for referring to objects, we demonstrated that a similar priming effect also occurs in young infants. This finding may indicate that word meaning is referential from the outset of word learning and that referential expectation drives, rather than results from, vocabulary acquisition in humans.     

A method for measuring dynamic respiratory sinus arrhythmia (RSA) in infants and mothers

The measurement of respiratory sinus arrythmia (RSA) in infants, children and adults is critical to the study of physiological regulation, and more recently, interpersonal physiological covariation, but it has been impeded by methods that limit its resolution to 30 s or longer. Recent analytical developments have suggested methods for studying dynamic RSA in adults, and we have extended this work to the study of infants and mothers. In the current paper, we describe a new analytical strategy for estimating RSA time series for infants and adults. Our new method provides a means for studying physiological synchrony in infant-mother dyads that offers some important advantages relative to existing methods that use inter-beat-intervals (e.g. Feldman, Magori-Cohen, Galili, Singer, & Louzoun, 2011). In the middle sections of this paper, we offer a brief tutorial on calculating RSA continuously with a sliding window and review the empirical evidence for determining the optimal window size. In order to confirm the reliability of our results, we briefly discuss testing synchrony by randomly shuffling the dyads to control for spurious correlations, and also by using a bootstrapping technique for calculating confidence intervals in the cross-correlation function. One important implication that emerges from applying this method is that it is possible to measure both positive and negative physiological synchrony and that these categorical measures are differentially predictive of future outcomes.     

In vivo studies of brain development by magnetic resonance techniques

Understanding of the morphological development of the human brain has largely come from neuropathological studies obtained postmortem. Magnetic resonance (MR) techniques have recently allowed the provision of detailed structural, metabolic, and functional information in vivo on the human brain. These techniques have been utilized in studies from premature infants to adults and have provided invaluable data on the sequence of normal human brain development. This article will focus on MR techniques including conventional structural MR imaging techniques, quantitative morphometric MR techniques, diffusion weighted MR techniques, and MR spectroscopy. In order to understand the potential applications and limitations of MR techniques, relevant physical and biological principles for each of the MR techniques are first reviewed. This is followed by a review of the understanding of the sequence of normal brain development utilizing these techniques. MRDD Research Reviews 6:59-67, 2000.     

Shedding light on words and sentences: near-infrared spectroscopy in language research

Investigating the neuronal network underlying language processing may contribute to a better understanding of how the brain masters this complex cognitive function with surprising ease and how language is acquired at a fast pace in infancy. Modern neuroimaging methods permit to visualize the evolvement and the function of the language network. The present paper focuses on a specific methodology, functional near-infrared spectroscopy (fNIRS), providing an overview over studies on auditory language processing and acquisition. The methodology detects oxygenation changes elicited by functional activation of the cerebral cortex. The main advantages for research on auditory language processing and its development during infancy are an undemanding application, the lack of instrumental noise, and its potential to simultaneously register electrophysiological responses. Also it constitutes an innovative approach for studying developmental issues in infants and children. The review will focus on studies on word and sentence processing including research in infants and adults.     

Pupillometry in Infancy Research

The human pupil is a small opening in each eye that dilates in response not only to changes in luminance, but also to novel events. Therefore, changes in pupil diameter are an attractive measure in studies on infants’ and young children’s physical and social cognition. However, designing and interpreting pupillometry studies for developmental populations come with caveats. Here we give an overview of how psychologically induced changes in pupil diameter have been investigated and interpreted in developmental studies. We highlight the methodological challenges when designing experiments for infants and young children and provide several suggestions to address common problems. The fact that pupillometry provides a sensitive measure of the time course of responses to novelty extends the scope of possibilities for researchers studying infant cognition and development.     

The Dubowitz neurological examination of the full-term newborn

In an ideal world, each neonate should have a comprehensive neurological examination but in practice this is often difficult. In this review we will describe what a routine neurological evaluation in the full-term neonate should consist of and how the Dubowitz examination is performed. The examination has been used for over 20 years and can be easily performed in a short time as the recording sheet provides simple instructions together with simple diagrams to make the recording and the scoring easier. We will also indicate how the examination can be used to identify infants with neurological abnormalities, describing clinical signs which can help to differentiate infants with peripheral neuromuscular disorders from those with central nervous system involvement. The correlation between clinical and imaging findings in infants with neonatal brain lesions will also be reported. Finally we will briefly describe how and when to apply an optimality scoring system in a research setting.     

Frontal cortex functioning in the infant broader autism phenotype

Atypical attention has been proposed as a marker of the broader autism phenotype. In the present study we investigated this and the related process of inhibitory control at the youngest possible age through the study of infant siblings of children with an autism spectrum disorder (Sibs-ASD). Both attention and inhibition have been related to the frontal cortex of the brain. Nine- to ten-month-old Sibs-ASD and low-risk control infants completed the Freeze-Frame task, in which infants are encouraged to inhibit looks to peripherally presented distractors whilst looking at a central animation. The attractiveness of the central stimulus is varied in order to investigate the selectivity of infants’ responses. In line with previous studies, it was found that a subset of Sibs-ASD infants had difficulty disengaging attention from a central stimulus in order to orient to a peripheral stimulus. The Sibs-ASD group also showed less Selective Inhibition than controls. However, Sibs-ASD infants did demonstrate Selective Inhibitory Learning. These results provide preliminary evidence for atypical frontal cortex functioning in the infant broader autism phenotype.     

Neurocomputational mechanisms of reinforcement-guided learning in humans: A review

Adapting decision making according to dynamic and probabilistic changes in action-reward contingencies is critical for survival in a competitive and resource-limited world. Much research has focused on elucidating the neural systems and computations that underlie how the brain identifies whether the consequences of actions are relatively good or bad. In contrast, less empirical research has focused on the mechanisms by which reinforcements might be used to guide decision making. Here, I review recent studies in which an attempt to bridge this gap has been made by characterizing how humans use reward information to guide and optimize decision making. Regions that have been implicated in reinforcement processing, including the striatum, orbitofrontal cortex, and anterior cingulate, also seem to mediate how reinforcements are used to adjust subsequent decision making. This research provides insights into why the brain devotes resources to evaluating reinforcements and suggests a direction for future research, from studying the mechanisms of reinforcement processing to studying the mechanisms of reinforcement learning.     

Relations between dynamics of parent-infant interactions and baseline EEG functional connectivity

Parent-infant interactions are one of the most critical and enduring aspects of infants’ experience. Qualities of parent-infant interactions are related to social-emotional and cognitive developmental outcomes, yet how parent-infant interactions shape the functional organization of the brain is only beginning to be understood. Functional connectivity provides information about how brain regions communicate. Patterns of functional connectivity, thus far understudied in infants, have emerged as markers of abnormalities in the organization of the brain in at-risk infants as well as individuals with neurodevelopmetnal and neurodegenerative disorders. The current study sought to inform our understanding of relations between qualities of parent-infant interactions and functional connectivity. We report relations between responsiveness, reciprocity, and emotional tone and functional connectivity in theta, alpha, beta, and gamma in infants ranging from 6 to 11 month of age (N = 51). Results showed frontal-posterior connectivity in theta was inversely related to all three dimensions of parent-infant interactions. Gamma and alpha connectivity were positively associated with responsiveness and emotional tone, respectively. Results are discussed in the context of the experience-dependent nature of brain development, emphasizing how parent-infant interactions might be leveraged to structure early organization of the brain to foster healthy social-emotional and cognitive developmental outcomes.     

The Robot in the Crib: A Developmental Analysis of Imitation Skills in Infants and Robots

Interesting systems, whether biological or artificial, develop. Starting from some initial conditions, they respond to environmental changes, and continuously improve their capabilities. Developmental psychologists have dedicated significant effort to studying the developmental progression of infant imitation skills, because imitation underlies the infant's ability to understand and learn from his or her social environment. In a converging intellectual endeavour, roboticists have been equipping robots with the ability to observe and imitate human actions because such abilities can lead to rapid teaching of robots to perform tasks. We provide here a comparative analysis between studies of infants imitating and learning from human demonstrators, and computational experiments aimed at equipping a robot with such abilities. We will compare the research across the following two dimensions: (a) initial conditions-what is innate in infants, and what functionality is initially given to robots, and (b) developmental mechanisms-how does the performance of infants improve over time, and what mechanisms are given to robots to achieve equivalent behaviour. Both developmental science and robotics are critically concerned with: (a) how their systems can and do go 'beyond the stimulus' given during the demonstration, and (b) how the internal models used in this process are acquired during the lifetime of the system.     

依恋的神经生理机制

在动物社会依恋的神经生物学研究基础上,研究者对人类依恋的神经生理机制进行了初步探讨,一致的结论是无论婴儿还是成人,不安全依恋个体的心率、皮质醇水平高于安全依恋的个体。而在依恋系统激活时婴儿和成人的脑电活动和大脑的功能定位研究却发现了不一致：较之安全依恋婴儿,不安全依恋婴儿的左侧前额大脑区域显示了较少的活动;成人依恋类型的脑机制研究并无定论。所有这些研究多为相关研究,今后有待于在神经生物水平上对依恋的基本理论问题如内部工作模式的意识和无意识性、母婴依恋与成人依恋的关系（特别是一般依恋表征和特殊依恋表征）以及母婴依恋对婴幼儿大脑发育的影响等问题展开深入研究     

Baby babbling at five months linked to sex hormone levels in early infancy

Gender-dependent differentiation of the brain at morphological, neurochemical and functional levels of organization have been shown to be primarily controlled by sex differences in gonadal hormone concentrations during pre- and early postnatal development. Indeed, previous studies have reported that pre- and perinatal hormonal environments influence brain development and, consequently, affect sex specific long-term language outcomes.Herein, we investigated whether postnatal surges of estrogen (estradiol) and androgen (testosterone) may predict properties of pre-speech babbling at five months. This study is the first attempt to investigate a possible correlation between sex hormones and infants’ articulatory skills during the typical postnatal period of extended hormonal activity known as ‘mini-puberty.’ A hierarchical, multiple regression approach revealed a significant, robust positive relationship between 4-week concentrations of estradiol and individual articulatory skills. In contrast, testosterone concentrations at five months negatively correlated with articulatory skills at the same age in both boys and girls. Our findings reinforce the assumption of the importance of sex hormones for auditory–vocal development towards language in human infants.     

国外婴儿动词习得的两种研究范式

通过介绍国外婴儿动词习得的研究范式, 一是习惯化研究(Habituation paradigm), 二是多通道优先注视范式(IPLP), 来揭示婴儿语言前概念形成的认知心理。国外的研究表明, 婴儿的动词习得晚于名词学习; 动词的成分习得(路径成分或是方式成分)在婴儿周岁前也有时间先后; 动词完整意义的获得还与母语的输入有密切关系。综述说明, 采用这两种研究范式研究语前婴儿的语言认知是较为经济和有效的。