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ON THE SHELF - Reviewed by Robin Tatu

ON THE SHELFSecrets of the Mind

Nerve patterns may be more revealing than genetic structure.

Connectome: How the Brain’s Wiring Makes Us Who We Are

by Sebastian Seung, Houghton Mifflin Harcourt 2012, 359 pages

Given the emergence of biomedical as a rapidly growing engineering discipline, it should come as no surprise that researchers in this field are making inroads into a crucial yet still mysterious part of the human body – the brain. In recent months, Harvard and Massachusetts Institute of Technology engineers have announced success in producing 3-D brain tissue in the lab, while at Brown University engineers are teaming with physicists to create more precise maps of our gray matter. For readers intrigued by such developments, Sebastian Seung’s Connectome: How the Brain’s Wiring Makes Us Who We Are serves as an excellent primer on past, present, and future brain research.

A professor of computational neuroscience in the departments of Physics and Brain and Cognitive Sciences at MIT, Seung believes that the key to unlocking the brain’s secrets lies in its neural connections, collectively known as the connectome. In the past, emphasis was placed on classifying regions of the brain to determine their functions – most of us remember the biology class exercise of labeling the cerebrum’s left and right hemispheres into the frontal, parietal, and temporal lobes, for example. Today, aided by increasingly sophisticated technology, Seung and others are shifting their attention to not only individual neural cells of the brain but also the complex patterns of their connections.

For readers hazy about the specifics of that biology class, Seung devotes early chapters to reviewing the basics, including how neural synaptic firings, refirings, and reweightings form the links of this intricate map. The theory of connectomics recognizes the importance of the brain’s structure but emphasizes that each person’s neural map develops in unique ways, based on his or her experiences. Those differences can provide more information than basic genetic structure, Seung argues. And if researchers can successfully locate, and track, and understand the connectome, it will enable them to tackle neurological disorders, improve everyday functions, and perhaps one day lead to supercharged versions of ourselves.

The author acknowledges in no uncertain terms the enormity of the work ahead. A pilot study to map the nervous system of the lowly earthworm – a creature possessing a mere 300 uniform neurons and 7,000 standardized synaptic connections – required 12 years. With 100 billion neurons, each forming multiple and far less uniform connections, the human brain presents a formidable, some would say impossible, undertaking. Indeed, mapping the human connectome is only the first step; the much greater work will involve analyzing its functions. “Connectomes are like vast books written in letters that we barely see,” he writes, “in a language that we do not yet comprehend. Once our technology makes the writing visible, the next challenge will be to understand what it means.”

Seung is nonetheless optimistic about future research, arguing that technology will provide much-needed assistance. The machines used to image the brain are becoming much more precise, producing slices “tens of thousands of times thinner than your typical prosciutto,” he writes. Moreover, computer programs now being developed can analyze enormous tracts of information that would have taken years, if not decades, if handled solely by humans. Discussion of these technologies may be of particular interest to Prism readers, who will most likely agree with Seung that “connectomics will ride on the back of the computer industry.”

The chapters in the latter sections of the book elaborate upon connectome theory, underscoring Seung’s conviction that these synaptic chains will reveal the “memory,” or record of past activity, with crucial information about how the brain and the body work. Comparing commonalities and differences will help identify abnormalities linked to neurological disorders, while the next steps will be to determine how to rewire and reweight problematic connections. The closing chapters of the book, which delve into futuristic possibilities of preserved brains and merging human brains with computers, may strike some readers as far too speculative. Overall, however, most will enjoy Sebastian Seung’s exuberant presentation of this cutting-edge research.


Robin Tatu is Prism’s senior editorial consultant.


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