97 of 101 people found the following review helpful
This is a very good book with a very strange name. "Connectome" means the entire collection of our brain's neuronal connections, the totality of how we are wired together. The subtitle "How the Brain's Wiring Makes Us Who We Are" is a fairly accurate representation of what the book is about. I believe this is the author Sebastian Seung's first book and he demonstrates quite a talent for explaining complex topics to a general popular audience.
What I particularly like about this book was the material was not at all the usual popular neuroscience stuff. This book covered new ground for me and I think will for most other readers. Seung spends a decent amount of time in the beginning explaining some basics about neurons and how the brain works, but it is when you get into the central ideas of the book that it gets really interesting.
One thing I really liked about the book was how the author explained the technologies and challenges required to actually create a connectome of even simple brains much less a human. According to Seung we don't have computers powerful enough or the tools to even analyze a cubic millimeter of a bird brain's connectome, much less a complete human brain a million times that size.
The whole book was compelling and informative and I can easily recommend it to others. One thing to keep in mind however, is that it is very futuristic in a sense. Seung's ideas are very plausible to me but still unproven and speculative. The technology to validate them is not going to be available for many years.
46 of 51 people found the following review helpful
I loved this absorbing book about neuroscience that took me through the past, present and future of the human brain. Though I'm not a scientist, I easily understood the challenges, clearly laid down by Dr. Seung, of finding connectomes. His very eclectic approach made it that much more interesting, as he argued from "first principles," and questioned all of his beliefs.
Prior to reading "Connectome," I had never heard the term, originally coined by Olaf Sporns and his colleagues in a 2005 paper. "A connectome is the totality of connections between the neurons in a nervous system. ... It is all of the connections." (xiii) "You may have heard of the $30 million Human Connectome Project, which was announced in 2010 by the U.S. National Institutes of Health (NIH). Most people don't realize that this project is only about regional connectomes, and has nothing to do with neuronal connectomes." (181) While Dr. Seung concedes that "in the immediate future, a regional connectome seems like the most useful kind for psychologists and neurologists" he is forward thinking to a day that all 100 billion neurons in the human brain are named, given a characteristic location and shape and are diagrammed. "To find connectomes, we will have to create machines that produce clear images of neurons and synapses over a large field of view." (140)
This is an ambitious goal. "We still don't know how many types [of neurons] there are, though we know the number is large. The brain is more like a tropical rainforest, which contains hundreds of species, than a coniferous forest with perhaps a single species of pine tree. One expert has estimated that there are thousands of neuron types in the cortex alone." (176) The connectome of a small roundworm (C. elegans) took seven years to "map" even though it has only 300 neurons scattered throughout its body. (xi) Seung imagines the human connectome could be completed by the end of this century thanks to rapid advances in technology for imaging the brain and slicing brain tissue, and high-speed computers to crunch the data.
This is all very fascinating and futuristic, but aside from connectome, this book is full of interesting information about intelligence, the effect of drugs on the brain, how the brain repairs itself after injury or stroke, as well as history and philosophy. For instance:
"Other animal species, such as lizards, are able to regenerate large parts of their nervous systems after injury. And human children regenerate better than adults do. In the 1970s, when physicians realized that children's fingertips regenerate like lizards' tails, they stopped attempting to reattach severed fingertips through surgery; now, they simply let the fingertips grow back. Hidden powers of regeneration might lie dormant in adults, and the new field of regenerative medicine seeks to awaken them." (221)
"Neurons continue to grow branches well after birth. This process is called the "wiring" of the brain, since axons and dendrites resemble wires. Axons have to grow the most, since they are much longer than dendrites. Imagine the tiny growing tip of an axon, known as a "growth cone" for its roughly conical shape. If a growth cone were blown up to human size, its travels would take it to the other side of a city. How is the growth cone able to navigate such long distances? Many neuroscientists study this phenomenon, and they've found that the growth cone acts like a dog sniffing its way home. The surfaces of neurons are coated with special guidance molecules that act like scents on the ground, and the interstitial spaces between neurons contain drifting guidance molecules that act like scents in the air. Growth cones are equipped with molecular sensors and can "smell" the guidance molecules to find their destination. The production of guidance molecules and sensors for these molecules is under genetic control. That's how genes guide the wiring of the brain." (106)
For some inexplicable reason, I found the following most interesting:
"The need for inhibition might be the chief reason why the brain relies so heavily on synapses that transmit chemical signals. There is actually another kind of synapse, one that directly transmits electrical signals without using neurotransmitter. Such electrical synapses work more quickly, since they eliminate time-consuming steps of converting signals from electrical to chemical and then back to electrical, but there are no inhibitory electrical synapses, only excitatory ones. Perhaps because of this and other limitations, electrical synapses are much less common than chemical ones." (56)
Any reader interested in preserving his or her brain in hopes of achieving immortality will want to read the chapter, "To Freeze or to Pickle?" Cryobiology is examined scientifically as well as from ethical and philosophical points of view.
35 of 39 people found the following review helpful
"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.
77 of 94 people found the following review helpful
Sebastian Seung is a man on a mission. Far from denying that our genomes play a big part in shaping who we are (and become), he is equally convinced that it is a very incomplete picture. Seung aims to convince us (and his peers in neuroscience) that the other big part of the "how we become who we become" picture will be found in the new science of connectomics (pronounced connect-ow-miks). While the book is a very fascinating read, and Seung does a good job explaining how and why the brain's 'wiring' (the connectome) forms as it does, I believe the book is a bit premature. Much of what Seung says is either already well-known (at least, from other popular books I've read) or so conjectural that Seung is hypothesizing more than arguing.
The first section deals with the history of brain science, from eugenics to what Seung calls our current "neo-eugenics". Eugenics was the late 19th and early 20th century "science" that measured people's abilities by the size and shape of their brain. Particularly, different areas of the brain were believed to have different functions; the larger your brain was in a certain area, the more brain power you were said to have in the skill that area was said to control. While modern science has learned that much of eugenics was wrong (from what eugenicists said was each brain section's domain, to overestimating how much brain size relates brain function), Seung is not satisfied that our modern neuroscience has gotten completely over eugenics. Yes, we know that each brain has areas and each area has different functions. And we know that brain size (and brain area size) LOOSELY correlates to brain function. But we are missing what seems like a big piece of the puzzle. And that piece is studying not only brain areas and their size, but also what the connectome looks like in those areas.
The next several sections are devoted to discussing how the brain's connectome forms, and how much (or how little) genes seem to play in directing it. The conventional view is that neural connections form when something is learned, and connections grow stronger or weaker based on how much those connections are used. Seung's hypothesis is a bit different: he believes that connections more likely form randomly, and the ones that aren't used then disappear (while the ones that are used grow stronger). Seung also describes some of the computer technology that could be used to look more closely at the connectome in much the same way as we've used computer technology to decipher the human genome. (While Seung is a pretty good writer, this particular chapter might benefit from an edit, as I waded through about ten pages recounting the history of how technology has enhanced science to get to Seung's point).
Part IV focuses on Seung's arguments about how examining the connectome may offer good insight into why people become how they become. What causes autism, why there is variance in populations in IQ, why different people are good at different things, etc. Much of the contemporary literature chalks a good amount of these answers to genetics and looks for correlations between genetic markers and specific traits. Seung doesn't deny the fruitfulness of this approach, but he is curious about whether there are neural connections that correlate with particular behavioral traits. If so, it is quite possible that we can figure out what induces neural connections to form, and whether or not the brain can alter its connectome. Unlike genomics, which has a very deterministic feel - you can't change your genome, after all - connectomics may offers us not only a richer understanding of our brains, but maybe learn that some of our traits are more plastic as research now suggests.
The final section is a very speculative section on whether the future might see us able to preserve brains for future study, etc.
While I did learn quite a bit from this book, and while Seung is a pretty decent popular writer, I came away a little less than impressed. First, I am not sure I buy Seung's depiction of much modern neuroscience as unduly neo-eugenic. Now, I am a lay reader in neurscience, but I seriously doubt whether contemporary neurscientists would really DENY that the connectome likely contributes a great deal to human development. I suspect - again, as a layreader - that Seung's plea for a new science of connectomics is probably not that different from where others in the field want to go.
Secondly, it seems like a lot of Seung's argument - and he admits this, to his credit - is speculative. Not that there is anything at all wrong with hypothesizing, but if convincing people to test (or find out how to test) new hypotheses about the brain is the goal, then the lay public is probably the last audience one should be aiming for.
So, while the book was quite interesting and Seung does reasonably well at explaining very abstract neuroscience to a lay audience, he might have waited a few years to write this book. That way, rather than writing a book largely consisting of hypotheses (which as yet often can't be substantiated or falsified), he might have been able to write a more concrete book detailing what actually HAS been and IS being found out about the brain.
7 of 7 people found the following review helpful
on March 18, 2012
In so far as this is a book about the neural wiring of the brain, it provides a fairly good narrative for the layman about a fascinating topic. Seung has a simple, informal style, and introduces some interesting personal anecdotes. His digressions also tend to be interesting, such as his explanation for why Prozac may work, by encouraging the formation of synapses. My main complaint is that he devotes a bit too much time to science which is known to be incorrect such as 19th century phrenology, and sometimes even presents material he knows is wrong, but does not tell the reader until later. A good example of that is his treatment of the relationship of the Broca and Wernicke regions and their role in speech, comprehension and what used to be called "conduction aphasia" (p. 180). I knew enough to be confused, to run to the internet, only to have Seung later discredit what he had reported.
One thing I particularly liked about Seung's approach is that he conveys the scientific method very well. He shows how new advances in understanding often depend on new advances in instrumentation and has a good narrative on the advances which have been made in the instrumentation for capturing what the neural connections are. He explains how the controversy about the plasticity, or lack thereof, of the adult brain, will be resolved by being more specific on what the adult brain can and cannot do as regards "rewiring" (p.128).
In so far as "Connectome" is a advocating a particular approach to neuroscience, it is neither convincing nor particularly interesting, so I would recommend just reading chapters 1-9. Incidentally, Seung is not up on the role of epigenetics in explaining the differences in identical twins (p.202).
7 of 7 people found the following review helpful
on June 1, 2013
I expected Sebastian Sung's book to teach me the latest information about the brain. But the author's intent was to make the text accessible to the general public and to tell a story more than to teach useful facts. The text is largely about historical brain theories going back to Aristotle. Professor Seung presents some facts but largely hypothesizes and postulates about what could be next steps in research, or what could be the brain's mechanisms - in other words, a lot of what-if scenarios. His stated goal (p. 277) was to empty his cup so that it could be filled, but he seemed to empty the cup over and over again, repeating the same information. And yet, he did not supply a basic helpful tool such as a drawing of an axon versus a dendrite.
I felt he could have made his points in 20 pages; I took only a half-page of notes on an almost 300 page book. I expected a more academic treatment, but even though he includes a lengthy bibliography, he makes no actual citations, so i can't easily reference the original sources. By background, Professor Seung is a theoretical physicist, but in "Connectome" he seems to be a non-practicing theoretical neuroscientist. Why should we care.
9 of 10 people found the following review helpful
The author describes and puts in context the nature and value of the Connectome; a comprehensive (down to microscopic detail) map of all nerve cell connections in the brain. He begins with a clear (to the lay public) description of the last few hundred years of accomplishment in understanding the human brain and the nervous system. He then describes his own unique research with the goal of mapping all nerve cell interconnections including the root-like processes known as dendrites. He fully admits that this is a difficult and evolving process but points to a methodology by which it will be eventually accomplished. He describes the exciting implications of this process in terms of mapping and understanding all human memory and "the engram". He speculates how the accomplishment of a complete neural map of a living human being might lead to a form of synthetic immortality.
The author Sebastian Seung is a professor of computational neuroscience at MIT, and an investigator in the Howard Hughes Medical Institute. He has been widely cited in the New York Times, Technology Review and the Economist magazines, and gave an exciting and widely viewed video lecture at a TED symposium.
4 of 4 people found the following review helpful
First, these recurring terms need to be abundantly clear to the reader to grasp the concepts in the book. As straight forward as they may sound, it was a challenge to fully understand the mechanism of each component of brain information exchange. I had to look up these definitions from numerous sources outside of the book as many were too technical and vague to the lay person.
Neuron: Brain cells that number in the billions in humans. Their function is to process, transmit to and receive information from other neurons by chemical or electrical signaling. Each neuron is connected to thousands of other neurons via synapses.
Synapse: The juncture at which information is exchanged between two neurons.
Axon: The branched threadlike extension of a neuron that transmits impulses away from the neuron to another (transmitter).
Dendrite: The branched threadlike extension of a neuron that receives impulses from another neuron (receiver).
Connectome: The map of the neural connections in the brain (wiring).
Connectomics is the process of creating this map, just as genomics is the process of mapping the DNA. Through Connectomes we hope to better understand the underlying mechanics of the brain to first explain why every brain is so unique, and second to harness this understanding to cure brain maladies such as schizophrenia or autism, and lastly, to enhance the capacities of the brain. According to Mr. Seung, the wiring of the brain is what sets apart one individual from another, and the connectome is essentially what makes you who you are. The problem is, our current understanding of the wiring of the brain is too primitive. We do not have the means to map even the simplest of the connectomes of one area of the human brain. Technology must advance far beyond what is available currently to facilitate this effort. So much of this book dabbles in the theoretical world with little empirical evidence, owing to the vast complexities of the brain. And some of the material is drab, and not very gripping to those readers who have a casual interest in the inner workings of the brain. The last couple of chapters breathe life back into the book with some philosophical discussions pertaining to how connectome can benefit our state of affairs. For example, we could conceivably upload our connectome into a computer and have our consciousness replicated without the need for our physical bodies.
Connectome calls to attention a field of neuroscience that is in its infancy, but ultimately, the effort proves futile as nothing concrete in connectomics surfaces. Perhaps a decade from now there will be discoveries worthy of revisiting the subject.
By the way, if you view the book cover from a distance, you may notice the resemblance with the Author's face.
9 of 11 people found the following review helpful
I LOVE LOVE LOVE this book.
99% of my reading material is fiction. I've often come across non-fiction that was far too "dry" or dumb-ed down to keep my interest. Sebastian Seung has written this wonderfully! It will easily appeal to fans of non-fiction and fiction alike, is a fascinating topic anyone would find engrossing, and manages to keep you hooked.
You do not need to be a neuroscientist to enjoy "Connectome." The first person viewpoint in which Seung writes often makes the book feel like a conversation or a lecture. (I can certainly believe he is a professor!) Without dumb-ing the book down (my pet peeve), Seung succinctly covers a vast amount of information using a mixture of concrete examples, studies, relevant metaphors, and occasional images. This is one of those books you will want to re-read or add those colorful Post-it Flags for marking specific pages to reference later.
Nearly every page of this book is a "conversation piece." I would literally have to put down the book to call my boyfriend and discuss what I'd just read; luckily he was equally interested and more than happy to discuss it. (He is borrowing my copy to read next.)
I strongly encourage everyone to read "Connectome." Even if sitting down and reading an entire book isn't your thing, even skimming through and reading snip-its will be well worth your time & undoubtedly fascinating. As an avid reader I do not say this lightly, but this is a book not to miss.
10 of 13 people found the following review helpful
on February 8, 2012
For those interested in understanding the current state of knowledge on how the brain creates consciousness, this book is a perfect complement to Dr. Michael Gazzaniga's recent Who's in Charge?: Free Will and the Science of the Brain. Gazzaniga describes the functioning of the brain at the smallest level of the neuron and at the largest level of how the brain as a whole creates consciousness. This book focuses on the middle-ground in between --- on how neurons network to assemble the biological circuitry responsible for the thoughts, associations, and memories that create consciousness. Dr. Seung calls this neural circuitry "the connectome."
I approach this topic from the perspective of wanting to know how the brain is able to store a seemingly infinite amount of information. We seem to be able to store and recall every sensation of our lives. Our ability to learn seems to be unlimited. Scientists are able to use their brains to discern the nature of the entire universe from its smallest subatomic particle to its largest megastructures.
Then comes the speculative part: if we learn how the human brain stores and processes information so as to create consciousness what will we be able to do next? Will we be able to synthesize higher intelligences? Will we learn to immortalize our beings by uploading our brains to undying machines? How about uploading our consciousness to a thousand machines, creating a thousand replicas of ourselves? Will we be able to do the "Vulcan mind meld" of integrating our conscious minds with those of other people and machine intelligences? Providing speculative answers to these kinds of questions are found at the end of the book.
But first we have to learn how the human brain does its thing. Here is what I took away from the book:
* The brain's "connectome" is extremely dense. Those hundred billion neurons in our brains are like miniature redwood trees. Each one makes thousands of connections with other neurons. Some neurons span the entire brain, making connections with every part of it.
* The connections themselves are variable. Some are strong and some are weak. Some are influenced by connections with OTHER neutrons. The process is dynamic. As experiences enter our consciousness some connections are strengthened while others are weakened or dropped.
* The complexity of the brain is unfathomable --- a hundred billion neurons; seven thousand connections per neuron; variable strength in the connections; and connections that may be activated by OTHER connections of other neurons in other parts of the brain.
* The brain constantly regenerates by creating new connections between neurons and by destroying connections that are not used. Destruction is necessary to prevent memories of lesser importance from "drowning out" memories of higher importance.
* We've learned some of methods by which the neural networks in our brains parse incoming data. Studies reveal that there is a specific neuron in each test subject's brain that recognizes a picture of Jenifer Aniston. Another specific neuron recognizes Tom Cruise. It seems that these particular neurons sit at the apex of networks that parse images of people. When the right combination of characteristics filter up from lower levels in the net, either the "Jenifer Aniston" or "Tom Cruise" neuron is triggered to recognize that particular combination of characteristics.
* This book is also delightful for what it DOESN'T talk about. I decided right off the bat that it would be worth at least three stars when I searched for "free will" and found no instances of that annoying topic.
After describing the current state of knowledge about the connectome, Seung addresses the speculative questions of whether we can amplify or copy human intelligence and consciousness. As a practical matter, immortalization of consciousness means "Is it worthwhile to pay somebody $25,000 to freeze my head when I die?" Here again there are questions to be asked.
The primary question is "Completeness" --- how complete does the restoration of the connectome have to be in order to bring a deceased brain back to conscious life? Is consciousness wholly defined by the neural connections or might it be defined lower down by the "ion channels" and perhaps even the quantum states of atoms within the neurons? Might each neuron be infinitely diverse and therefore impossible to duplicate by artificial means?
At this point it would be amusing to mention all the science fiction stories about people being revived by cryonics hundreds of years in the future, like the poor fellow whose frozen brain was revived in the 25th century only to be sold to a bootleg electronics contractor who installed it as a thermostat in a space station. These sorts of speculations have been staples of scifi for my entire life. But now it does seem that we have at least learned to ask the right QUESTIONS about how to use our knowledge of the connectome to amplify or immortalize our intelligence in limited ways.
We also seem to have learned how to mimic the brain's neural networks in more mundane applications. For example, the knowledge of how the connectome processes an image in order to trigger the "Jen Aniston" or "Tom Cruise" neuron would have obvious implications for computerized pattern recognition. It also raises the prospect of mind-reading. If the same neurons fire the same way in everybody's brains, then we would be able to tell who is thinking about "Jen Aniston" or "Tom Crusise" or eventually anything else by examining the firing of particular neurons. Perhaps a person's memories can be scanned out of their brains by examining the patterns of their neurons firing.
This book succeeds on two counts:
1. It provides a solid grounding into the anatomy of the brain at its intermediate level of neural networks.
2. It sounds an early warning into the scientific and ethical issues that future brain, mind, and cybernetic researches are likely to open up. The ethical issues of stem cell research will seem like small controversies compared to the question of whether we should be cloning our minds into machine intelligence.
The book is most enjoyable for a layperson. I felt that some of the details were over-described, but then Seung is also writing for a professional audience. It was only an occasional page or two of detail that I really felt compelled to skim past. I came away feeling that I am up to speed on the current state of brain/mind/consciousness research.