book “is to lay out many of the neurobiological facts we have about the
developing, adult, and aging brain.” (p. 3) The author is an eminent
neuroscientist who is ...
Book Review
The Great Brain Debate: Nature or Nurture? John E. Dowling. Washington, DC: Joseph Henry Press, 2004. 189 pages. ISBN 0-309-09223-X Reviewed by David A. Goss, OD, PhD, FAAO, FCOVD-A, Indiana University, Bloomington, IN The title of this book implies that it might provide within its pages some definitive answers to one of the biggest scientific questions: the relative influences of inheritance and environment. However, the author does not make such a big promise when he states in the introduction that the purpose of the book “is to lay out many of the neurobiological facts we have about the developing, adult, and aging brain.” (p. 3) The author is an eminent neuroscientist who is highly recognized for his research on the retina. The book consists of three parts The Developing Brain, The Adult Brain, and The Aging Brain. Rather than present a comprehensive review of brain science, the author selects a few example areas of research and summarizes how the research suggests that either inheritance or environment plays the major role in resultant structure or function. Dowling starts in Chapter 1 , “ B u i l d i n g a Brai n,” with emb r y o l o g i c a l development , d isc u ssi n g h ow neural cells p r o l i f er a t e, how neurons differentiate, and how axons reach their intended locations. The author notes that much of the initial development is dependent upon Volume 37/Number 2/2006
“genetically specified molecular mechanisms.” Next, in Chapter 2, the author discusses maturation of the circuitry of the brain in development, using development of the visual pathways and visual cortex as an example. Visual deprivation experiments are used to introduce the concept of critical periods. Examples of developing behaviors in Chapter 3 are l e a rning la ngua ge s, the development of birdsong, and sound localiz a tion in ow ls. The se examples are used to suggest that certain abilities must be learned before maturity if they are going to be learned completely. Chapters 4 and 5 (Part II) deal with the adult brain. Experiments demonstrating cortical plasticity are described. Mechanisms by which the strength of synapses can be modifie d a nd by w hic h ne w synapse s c a n be forme d a re discussed. One of the riddles of adult brains that Dowling struggles with is that humans have greater plasticity at the perceptual level, but appear to have less plasticity at the neurona l le ve l, tha n low e r vertebrates. The author also considers the relation of inheritance and environment in IQ. Here he appears to come down more on the side of nature when he states that “…it is the most deprived children whose IQs can be raised most by environmental intervention. The IQs of children raised in solidly supportive and caring environments are less environmentally related….” (p. 134) In Chapter 6 (Part III), neuronal and cognitive changes with age are discussed. Much of the chapter deals
w ith the c e llula r c hanges i n Alzheimer’s disease, Parkinson’s disease, and retinitis pigmentosa. A concluding chapter reiterates some of the points made throughout the book. Dowling observes that “…genetic directives are clearly most critical in brain building, although the environment can also pla y some role , wher eas environmental factors play the fundamental role during brain maturation, although there is genetic restraint.” (p. 165) The material in the book is clearly presented. It provides insight into how inherent mechanisms direct early neural development and how experience can refine neuronal circuitry. Although there are no definitive global answers to the great nature or nurture brain debate, it offers good examples of how inheritance and environment can affect neural function. A list of twelve books for further reading and an index are included, but reference citations to the primary literature are not listed. A few figures in each chapter are used to good advantage in illustrating principles discussed in the book. This book makes for some interesting reading and can yield a gre a te r a ppre c ia tion f or t he complexities of the nature vs. nurture debate.
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