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The Great Brain Debate

The Great Brain Debate: Nature or Nurture?

John E. Dowling
Copyright Date: 2004
Pages: 200
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  • Book Info
    The Great Brain Debate
    Book Description:

    Whether our personality, intelligence, and behavior are more likely to be shaped by our environment or our genetic coding is not simply an idle question for today's researchers. There are tremendous consequences to understanding the crucial role that environment and genes each play. How we raise and educate our children, how we treat various mental diseases or conditions, how we care for our elderly--these are just some of the issues that can be informed by a better understanding of brain development.

    InThe Great Brain Debate, the eminent neuroscience researcher John Dowling looks at these and other important issues. The work that is being done on the connection between the brain and vision, as well as the ways in which our brains help us learn new languages, are particularly revealing. From this groundbreaking new research, Dowling explains startling new insights into how the brain functions and how it can (or cannot) be molded and changed. By studying the brain across the spectrum of our lives, from infancy through adulthood and into old age, Dowling shows the ways in which both nature and nurture play key roles over the course of a human lifetime.

    eISBN: 978-1-4008-4138-7
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
    (pp. 1-4)

    The United States Congress designated the 1990s as the Decade of the Brain, but some suggest that the twenty-first century will be the century of the brain, when the last great frontier in biology —an understanding of the most complex biological system, the human brain—will be breached. Already the considerable advances made in neuroscience over the past 50-100 years are being called upon to explain many things about human behavior. Interdisciplinary programs are appearing in our colleges and universities asking what various disciplines and fields can learn from neuroscience and vice versa. At Harvard, I have been associated with...

  4. Part I The Developing Brain

      (pp. 7-32)

      Understanding how the brain forms is one of biology’s greatest challenges. From a relatively few undifferentiated cells in the young embryo, all of the neurons and glial (supporting) cells arise. The adult human brain contains about 100 billion neurons (a conservative estimate) and perhaps 10 times as many glial cells. Because virtually all neurons and most glial cells form before we are born, an embryo would generate approximately 250,000 cells per minute in the womb if brain cell generation were constant over the nine-month gestation period. However, most neurons are generated in the first four months of gestation, so the...

      (pp. 33-56)

      In the first chapter I described how the brain is formed—how precursor cells become specified as neurons, how these nascent neurons migrate to appropriate positions in the embryonic brain and then differentiate into specific neuronal subtypes. I discussed how axons find their way to their targets and, finally, how synapses are formed. These events establish the framework of the brain, and clearly they depend on genetically specified molecular mechanisms. Thus, what I have described so far depends mainly on nature.

      Next, I’ll discuss the maturation of the brain, brain circuitry, and behavior, and here experience—nurture—plays a critical...

      (pp. 57-80)

      In the last chapter I described the maturation of the brain and how experience molds it, primarily by pruning. Dendritic and axonal fields of neurons are refined, synapses rearranged, and neurons even lost. There are critical periods for much of this plasticity, sensitive times early in life when various aspects of brain structure and function are particularly susceptible to alterations. In this chapter I explore examples of higher brain function development, and many of the notions described in the previous chapter hold here as well. I also discuss some new facets of brain development.

      Language is certainly one of the...

  5. Part II The Adult Brain

      (pp. 83-110)

      The previous two chapters emphasized the point, certainly correct, that the young developing brain is much more plastic than the adult brain. Indeed, in language and birdsong development as well as sound localization in owls, puberty or sexual maturation seems to be the point when critical developmental abilities are lost. And it is common experience that motor skills—riding a bicycle or even swinging a golf club—are much more easily learned as a youngster before puberty. And once these skills are learned as a youngster they tend to stay with us for the rest of our lives.

      The view...

      (pp. 111-136)

      The previous chapter described various ways cortical circuitry can be modified—from simply altering the strength of synapses to neurons extending new branches and making new synapses. It deftly avoided one of the most contentious questions of the day: Can new neurons be generated in the adult mammalian brain? New neurons can be generated in nonmammalian brains, as I shall describe below, but what about the mammalian brain? This is a hotly debated issue that has implications not only for understanding the adult mammalian brain, but perhaps even more so for the aging brain. It has implications too for the...

  6. Part III The Aging Brain

      (pp. 139-160)

      We have all witnessed the deterioration of our parents or grandparents as they aged. Too often, it is a sad deterioration with a loss of quality of life as they fail mentally. At the same time, we read about the marvelous advances in medicine that are supposed to make us healthier and live longer. What is going on? Are people living longer? And if so, what are the consequences? Is it likely that we could live to be 150 or even 200 years old, and what would it take for us to achieve that goal if, indeed, this is something...

    (pp. 161-174)

    Neurobiological studies of the developing brain provide much information on how the brain initially forms in the fetus. At first glance, we might conclude that early brain development depends strictly on nature—intrinsic genetic directives—and Chapter 1 appears to support this view. But it is important to recognize that environment and nurture can also play a role in early brain development. I use the term ʺenvironmentʺ here and in the rest of this discussion on brain development very broadly. Essentially, I mean nongenetic factors, of which environment is only one, although perhaps the major one. As I discussed in...

    (pp. 175-176)
    (pp. 177-178)
  10. INDEX
    (pp. 179-190)