"Worthwhile things that have never been done can only be done by means that have never yet existed," Sebastian Seung tells us in CONNECTOME. Mapping the 100+ billion neurons in the human brain is certainly one such project, and we are far from having the means to do so.
But already, with the mapping and study of the 300 neurons in the C.elegans roundworm and ongoing development in imaging technology (such as the automated ultramicrotome), we are making strides toward understanding the structure and function of diverse neurons, and how their interactive network operates.
Author Seung is a professor of neuroscience at MIT, and a leading researcher on neural networks and the still-theoretical connectome. The term connectome, first coined in 2005, refers to the totality of connections between neurons. The field of neuroscience involves learning how neurons are strengthened, weakened, weighted and eliminated and how they connect and reconnect, rewire, and regenerate.
The first half of his book begins with chapters about: 1) the structure and role of neurons; 2) connectomes and their interconnectivity; 3) how memories are impressed and stored; 4) and genes. The next sections cover the development of imaging technologies and the lifelong task of reading and interpreting the voluminous data acquired.
Unfortunately, at this point, Seung comes across less as a scientist and more as a science fiction writer as he resorts to speculation about cryonics (brain and body preservation), uploading brains into computers, and immortality. The book would be much more substantial if he omitted the last few chapters.
Seung, however, is a talented writer with the unique ability to impart scientific theory in understandable language. Obviously possessing a highly associative brain himself, he is skilled at explaining fundamentals of neuroscience through the frequent use of everyday analogies.
He compares the process of dendrites spiking to a weighted voting system influenced by favoritism. All votes must be in before dendrites know they can spike, he tells us, further explaining that some votes count more than others -some neurons and their synapses transport more important signals than others do, and therefore have greater impact.
"If the axons and dendrites in the gray matter are like local streets, the axons of the white matter are like superhighways of the brain," he writes.
In another chapter, he briefly takes us on a "fantastic voyage". "Perhaps you are a protein molecule sitting on a molecular motor car running on a molecular track. You are being transported on the long journey from your birthplace, the cell body, to your destination, the outer reaches of the axon... To find an entire connectome, though, you'd have to explore every passage in the brain's labyrinth."
I was especially pleased that he compared RAM and hard drive memory to short-term and long-term memory in the brain - a comparison I make in computer skills classes I teach.
But I wish that Seung introduced us to the brain as a whole before zeroing in on neurons, and that he provided a detailed, labeled map of the parts of the brain. He included a lot of rough illustrations and diagrams, but few quality photos.
I thought that his discussion of factors contributing to memory was incomplete - he didn't even mention the emotional intensity of a learning experience, multi-sensory involvement, and mindful attention and intention, all factors I found to be critical during graduate training in education and psychology, as well as my personal brain fitness "workouts".
My primary criticism of the book, however, is that Seung doesn't differentiate enough between proven facts, generally accepted theories, his own personal theories, and pure speculation.
Nevertheless, his often chatty and informal yet highly informative writing style is enjoyable. His numerous and sometimes humorous analogies help us envision neural activity, understand the intricacies of the connectome, and appreciate the immense accomplishments and challenges of neuroscience. I rate CONNECTOME 4 stars.