Grace Iarocci and Stephen A. Petrill
This chapter provides an overview of the current evidence on the behavioral genetic etiology of mental retardation. It begins with a history of the two-group approach and the need to differentiate between organic and nonpathological forms of mental retardation. Then, it presents evidence that genetic and environmental factors that contribute to variation in IQ in the general population may also lead to low IQ in persons with familial mental retardation. The chapter continues with a review of the new behavioral genetic work to identify DNA markers for intelligence. It outlines methodological challenges, with particular emphasis on how these issues pertain to the search for an etiological link between familial mental retardation and normal variation in general cognitive ability. It concludes with a discussion of familial mental retardation within the broader scope of the reciprocal relation between genetic and environmental influences.
Brain-based Methods in the Study of Developmental Disabilities: Examples from Event-related Potentials and Magnetic Resonance Imaging Research
Alexandra P.F. Key and Tricia A. Thornton-Wells
Numerous technologies are available for studying the brain basis of developmental disabilities, each of which has its advantages and disadvantages. These include electroencephalography (EEG), event-related potentials (ERP), magnetoencephalography (MEG), near-infrared optical tomography (NIROT), positron emission tomography (PET), magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRspect). This chapter focuses on two technologies—ERP and MRI—which are increasingly being used in research on developmental disabilities. It discusses how each methodology works and what kinds of research questions each is well suited to answer. It illustrates the application of these methods in four specific genetic disorders: Down syndrome, Prader-Willi syndrome, Williams syndrome, and fragile X syndrome. Finally, the chapter discusses gaps in current research, issues of experimental design, and suggests directions for future studies.
Michael I. Posner, Mary K. Rothbart, and M. Rosario Rueda
This chapter views attention as an organ system consisting of three brain networks with their own unique anatomy, connectivity, neuromodulators, and functions. These networks underlie the functions of attention including: obtaining and maintaining the alert state, orienting to sensory events, and voluntary control of responses. It traces the development of these attentional networks from infancy to adulthood. All three networks are present in infancy, but their functions and connectivity change in development. The change of control from the orienting to the executive network that takes place between infancy and childhood underlies the increasing role of voluntary control of emotions and thoughts. It examines how genes and environment influence this development and suggests avenues for further understanding of how attention develops.
Dyadic Interaction Between Mothers and Children with Down Syndrome or Williams Syndrome: Empirical Evidence and Emerging Agendas
Penny Hauser-Cram, Angela N. Howell-Moneta, and Jessica Mercer Young
This chapter highlights the theoretical foundations that have guided research on mother—child interaction. It discusses the physical and behavioral characteristics of children with Down syndrome (DS) that influence their social interactions, then reviews research findings on mother—child interaction in these dyads. It discusses research conducted during the past decade since the review in the last Handbook of Mental Retardation (Marfo, Dedrick, & Barbour, 1998) and proposes an agenda for future research. The chapter also describes the behaviors and processes related to Williams syndrome that are likely to be relevant to mother—child interaction. It proposes a research agenda that both builds on and is distinct from that related to children with DS.
Emergence of Higher Cognitive Functions: Reorganization of Large-Scale Brain Networks During Childhood And Adolescence
Pedro M. Paz-Alonso, Silvia A. Bunge, and Simona Ghetti
In the present chapter, we first provide an overview of neurodevelopmental changes in brain structure and function, which have implications for the development of higher cognitive functions as well as for other areas of research within developmental cognitive neuroscience. Second, we highlight neuroimaging evidence regarding the development of working memory and cognitive control processes, and the main neural mechanisms and brain networks supporting them. Third, we review behavioral and neuroimaging research on the development of memory encoding and retrieval processes, including episodic memory and mnemonic control. Finally, we summarize important current and future directions in the study of the neurocognitive mechanisms supporting the development of higher cognitive functions, noting that multidisciplinary approaches, different level of analyses, and longitudinal designs are needed to shed further light on the emergence and trajectories of these functions over development.
James P. Morris and Jessica J. Connelly
Every cell within a given organism contains the same DNA blueprint; in the case of humans, this means that the same DNA code can give rise to hundreds of different cell types with very diverse functions. The genome accomplishes this feat by organizing the DNA into domains that are transcriptionally active or inactive given the particular cell type and function. This occurs by modification of the DNA and the proteins bound to it; methylation of cytosine residues, DNA methylation, is one such “epigenetic” modification and is the focus of this chapter. The role of epigenetic influences on cultural diversity is poorly understood. Given the natural links between environment and biological function, epigenetic processes are poised to play a critical role in new approaches to understanding the biological underpinnings of culture.
This chapter aims to contribute to an improved understanding of the social brain and the rising tide of psychological health in children. It challenges certain misperceptions affecting scientific research and child-oriented policies, and it presents a “play and display” hypothesis that holds that spontaneous communication, play, and performance (social displays), uniquely developed in humans, are a major reason for our enlarged brains and are essential to the development of self/other-awareness, brain maturation, human culture, and healthy child development. The hypothesis is linked to pivotal theories in the social sciences, notably social mirror theory, ritual/speech coevolution theory, and the theory of anti-structure. Implications for child health are discussed, and the argument is supported by evidence relating to epigenesis, brain development, developmental psychology, paleoanthropology, neuroimaging research, and the culture-ready brain. The chapter concludes with some pointers for future child development policy.
Robin S. Chapman and Elizabeth Kay-Raining Bird
This chapter summarizes the strengths and weaknesses of the emerging language profile in children, adolescents, and young adults with Down syndrome (DS). It reviews in detail studies of expressive language skill in vocabulary, speech—motor skill, syntax, and pragmatics, and includes a section on studies of receptive language skill in vocabulary and syntax. Finally, the chapter considers proposed causes of the behavioral language phenotype and individual variation in its expression, and discusses the implications of the findings.
Language Development in Fragile X Syndrome: Syndrome-specific Features, Within-syndrome Variation, and Contributing Factors
Leonard Abbeduto, Andrea McDuffie, Nancy C. Brady, and Sara T. Kover
This chapter reviews what is known about the language problems of individuals with fragile X syndrome (FXS). The chapter is organized into four major sections. The first section provides a comprehensive characterization of the language problems typically associated with FXS, describing the extent and profile of delays and impairments and, where possible, the syndrome-specific features of the linguistic profile. The second section describes within-syndrome variation in the linguistic profile, emphasizing the relationship between language and gender and autism status. The third section considers the genetic and environmental factors that lead to the syndrome-specific features of, and within-syndrome variation in, the linguistic phenotype of FXS. The final section identifies important gaps in our knowledge of the language problems of FXS and suggests some directions for future research.
Laura Ferreri, Aline Moussard, Emmanuel Bigand, and Barbara Tillmann
In a society that is getting considerably older, it becomes important to identify potential mechanisms promoting successful aging to prevent, limit, and rehabilitate cognitive and emotional impairments typical of normal or pathological aging. Music is a powerful stimulus able to modulate widespread brain activations. Recent research has increasingly considered music as a promising, stimulating training and rehabilitation tool for improving cognition and promoting well-being and social connection. This chapter provides an overview of recent research investigating music and aging. It first focuses on the effects of music in normal aging, both in terms of musical expertise and simple musical exposure, with an additional section being devoted to the underlying brain processes. The chapter then considers the principal music-based therapeutic approaches used in pathological aging. Finally, the chapter underlines the main limitations and open questions arising from the existing literature, and discusses possible future directions for research on music and the aging brain.
Most sensory systems (auditory, tactile, olfactory, gustatory, motor, vestibular, proprioceptive) begin to function long before birth. The fetus is also capable of basic cognition (attention, memory, association, pattern recognition) and sensitive to emotion (biochemical and behavioral correlates). Abilities and behaviors that are based on these sensations, cognitions, and emotions have prenatal origins. Can prenatal psychology explain the origins of music? From about 20 weeks’ gestation, the fetus perceives the internal sounds of the mother’s body and her body movements. These behavioral patterns correlate with changes in hormone concentrations reflecting maternal physical and emotional states. The fetus may connect behavioral stimuli with biochemical stimuli by classical conditioning, motivated by the adaptive value of the mother schema—the baby’s multisensory perception of its mother. This theory can explain why music evokes strong emotions and why infants have adult-like sensitivity to musical structures, although music has no clear survival or reproductive value.
Laurel J. Trainor and Susan Marsh-Rollo
Many biological processes have rhythmic organization, including the perception and production of music. Rhythms organize information that unfolds over time; they aid in parsing that information into meaningful hierarchical groupings; and the regularities of rhythms enable prediction of, and preparation for, when important information will occur in the future. Expressive deviations from isochronous timing convey emphasis, emotion, and meaning. Young infants are sensitive to timing and rhythm in music but these abilities become much more sophisticated during childhood. In the beginning, timing characteristics of infant-directed singing relate to the communication of emotional information. Through development, children become enculturated to the rhythmic structures in their environment, develop the oscillatory brain processes to link auditory and motor aspects of entrainment, become able to entrain movements to auditory rhythms, and use the synchronicity of movements between people to help make judgments about social relationships and who to trust and befriend.
Anthony Brandt, L. Robert Slevc, and Molly Gebrian
Language and music are readily distinguished by adults, but there is growing evidence that infants first experience speech as a special type of music. By listening to the phonemic inventory and prosodic patterns of their caregivers’ speech, infants learn how their native language is composed, later bootstrapping referential meaning onto this musical framework. Our current understanding of infants’ sensitivities to the musical features of speech, the co-development of musical and linguistic abilities, and shared developmental disorders, supports the view that music and language are deeply entangled in the infant brain and modularity emerges over the course of development. This early entanglement of music and language is crucial to the cultural transmission of language and children’s ability to learn any of the world’s tongues.
Daphne Maurer, Laura C. Gibson, and Ferrinne Spector
This chapter provides a review of the hypothesis that synesthetic-like perception is present in infants and toddlers. Infants and very young children exhibit evidence of functional hyperconnectivity between the senses, much of which is reminiscent of the cross-sensory associations observed in synaesthetic adults. As most of these cross-sensory correspondances cannot be easily explained by learning, it is likely that these represent natural associations between the senses. In average adults, these 'natural associations' (e.g., large = loud) are felt only intuitively rather than explicitly. These observations have led to the proposal of the 'neonatal synaesthesia hypothesis', which purports that all individuals are born synaesthetic, with explicit conscious perception of these natural cross-modal associations dissipating over development in typical individuals. This dissipation is likely the result of experience-dependent synaptic pruning and/or inhibition of cross-sensory neural connections. At the same time, cross-modal associations matching those common in the environment might be assumed to be learned. This hypothesis is re-evaluated in light of recent research findings, and is examined in the context of current evolutionary models of neuronal recycling and emerging evidence of longitudinal changes in children with synaesthesia.
Julia Simner and Edward Hubbard
This chapter looks at synaesthesia in school aged children from approximately 5-6 years onwards. We examine how synaesthesia develops from its earliest roots both behaviourally and neurologically, and describe how this development can be affected by literacy and learning. We present evidence showing that synaesthesia emerges over time undergoing stages of 'growth' from an immature to more mature form. We also discuss the prevalence of childhood synaesthesia and the methodologies available for testing this. Next we consider how the condition can have an effect on a child's schooling experience and consider both its psychological and social impact. We show where the condition has costs and benefits for synaesthetic individuals and offer suggestions for parents and educators in their approach to dealing with the synaesthetic child.