Nature and nurture  pg. 2

Fluorescence microscope image of neurons (nerve cells) in the cerebral cortex, or outer portion of the brain, which is involved in conscious experience, including perception, emotion, thought and language.  The round center of each neuron represents the cell body, and the extensions are the dendrites that receive connections from other neurons.  The neurons are colored with different dyes.
Courtesy of Gregg Stanwood and Pat R. Levitt, Vanderbilt University
If genes were the sole force in brain development, it would be difficult to explain the profound difference between the mind of human beings and the nervous system of the worm, C. elegans, which serves as a model system for studies of the development of neuronal “wiring.” The worm has 19,000 genes, only about 11,000 fewer than human beings, yet the 302 neurons of the worm are far outnumbered by the trillions of nerve cells in the human brain.

What, beyond the sheer number of genes, could explain the quantum leap in neurobiological complexity between a human being and a worm? One key lies in how these genes are “packaged” in human versus worm nuclei. The human genome includes long stretches of non-coding DNA that regulate gene expression cell to cell. This extra genetic material provides an organized, highly complex and flexible molecular network capable of driving the computational genius of human brain circuitry, and capable of responding to extrinsic cues (sounds, sights, touch, food, light, drugs, toxins, cruelty, abuse) perhaps in a more limitless fashion than in simpler species.

In 2002, the opportunity to build new research relationships led me from the University of Pittsburgh, where I was chair of the Department of Neurobiology, to Nashville to direct the Vanderbilt Kennedy Center for Research on Human Development. The center has a rich history of embracing interdisciplinary approaches to study brain disorders. Nicholas Hobbs, Lloyd Dunn, Susan Gray and their colleagues at the Peabody College believed that they could create assessment tools to describe better the nature of a particular brain disorder and through this improved characterization, develop cutting-edge strategies for intervention and treatment. These visionaries imagined the possibilities of doing bio-behavioral research and intervention at a time when technologies had not caught up with their imaginations.

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