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This chapter presents an overview of mutations in the mouse that have improved our understanding of structural myelin proteins. Mouse genetics, in combination with molecular cell biology and morphology, has provide important insights into the process of myelination. For some myelin proteins, a specific function in the architecture of myelin can be demonstrated. In other cases, a more complex picture has emerged from overlapping loss-of-function and aberrant gain-of-function effects. The latter is a recurrent feature of natural point mutations with autosomal dominant (or X-linked recessive) inheritance.

This chapter reviews recent studies that suggest that it is no longer tenable to consider glial cells as passive support cells. These studies have shown that interactions between neurons and glial cells control neurogenesis, myelination, node of Ranvier formation, synapse formation, and maybe even neuronal signaling. It is argued that the development, structure, and function of the brain all depend on an intimate neuron-glia partnership. A full understanding of nearly all neurobiological processes must include consideration of the role of glial cells.

In parallel with the development of neuronal transplantation, glial cell transplantation has rapidly evolved as an experimental technique to study cellular interactions during glial development, and as a potential strategy for repair to remyelinate areas of persistent demyelination in clinical conditions. An important feature of all glial cell transplantation models is that the host environment into which cells are transplanted must contain non-myelinated axons of an appropriate diameter for myelination. Such environments can arise for a variety of reasons, and many have been used as host environments in transplantation studies, such as the non-myelinated axons of the retina or during development before myelination is complete. However, the majority of transplantation studies have been undertaken using one of two models.

At birth, an infant's brain and central nervous system contain all the components found in all adult brain, just as the newborn's body has all the parts in the right places, but the growth and development over infancy and childhood are as remarkable for the brain as for the body. Understanding the development of brain structure and function is critical to understanding the development of cognitive abilities. This chapter first reviews the basic physiological maturation of the brain and then links these changes with some examples of cognitive development. It discusses the physiological measures of brain development, myelination, maturation of white matter and gray matter, functional measures of neural development over childhood, experience and developmental changes, functional changes with development, neural correlates of the development of face processing, neural correlates of the development of language skills, and changes in brain structure and function across the lifespan.

Chapter 3 covers the basic neural mechanisms by which the brain undergoes an extreme makeover during adolescence. It starts with the proposition that the nervous system has only so many tools in the toolbox to accomplish this makeover and these tools can be categorized as either progressive or regressive. Progressive tools include neurogenesis, migration, axon outgrowth, and synapse formation. Regressive tools include programmed cell death and experience-dependent synapse elimination. Two analogies are used to help readers understand this process: house remodeling and gardening. These analogies are woven into the concepts of progressive and regressive developmental events, and they can be imagined as mechanisms that result in either gain or loss of function (e.g., a house addition might equal new neurons or new projections) or maximize efficiency and success (pruning of seedlings might equal programmed cell death). Research on increased myelination during adolescence is also discussed.

Chapter 4 focuses on research based primarily on imaging studies of the human adolescent brain. It highlights the extent of changes that occur, as well as the protracted nature of these changes, which take place over the second and third decades of life. Major themes of this chapter include (a) spatial and temporal differences in the adolescent development of particular brain regions; (b) puberty (i.e., gonadal hormones influence some, but not all, aspects of adolescent brain development); and (c) the timing and rate of developmental changes are critically important. Research on adolescent changes in white matter and connectivity is reviewed. The chapter also addresses aspects of adolescent development that are typical versus atypical, as well as the limitations of imaging approaches to understanding adolescent brain development.

Abstract: This chapter informs the reader of the discovery of nerve growth factor, how it plays an important role in bioprinting by directing the growth of the axons of nerve cells along specific paths to repair peripheral nerve injuries, and of the nascent efforts in bioprinting spinal cord scaffolds that may aid in the repair of spinal cord injuries. The chapter apprises the reader of the glial family of cells that provide myelination (insulation) for nerves in the central nervous system. Glial cells are as numerous in the central nervous system (i.e., the brain and spinal cord) as neurons (nerve cells). The chapter also explains fluorescently tagged calcium ion flow within bioprinted nerve tissue. Intracellular calcium—calcium within cells—controls key cellular functions in all types of neurons. For example, nerve cells cause a release of calcium ions that initiate muscle contraction.

The brain undergoes enormous changes from conception to age 18. Explosive growth, directed by genetic instructions and life experiences, is later counterbalanced by deletion of cortical connections through neural pruning. From the last trimester before birth throughout childhood, music plays a significant role in this process of development. Natural maturation leads to some improvements in music processing, while everyday living, including passive listening to music, brings about other changes. Informal music-making and formal musical training lead to further significant changes. Intensive and extensive music practice during childhood leads to specific changes in brain structure and function that persist through adulthood. Some of these changes have effects on learning in nonmusical domains, such as language. Important concepts from neuroscience, including myelination, plasticity, and optimal periods, are reviewed in relation to musical learning.