The Root of Thought: Unlocking Glia--the Brain Cell That Will Help Us Sharpen Our Wits, Heal Injury, and Treat Brain Disease 1st Edition

While the idea of uncovering the cellular basis for thought and consciousness is one of the most compelling areas in neuroscience, this book falls short of its title's promises. The thought that glia may be the neural cells of ultimate importance is, as Andrew Koob writes, a truly refreshing take on a science dominated by the study of neurons. However, this claim remains only superficially supported by the text of the book. For the lay reader, Koob's review of glial significance is easy to understand, requiring very little background knowledge of the nervous system, and may in fact be quite convincing and thought-provoking. Anyone with a background in science, however, will quickly note that this book often lacks in convincing technical details and instead fills in much of its space with indirect evidence and what appears to be largely speculation.

Synopsis

Koob begins his book with a lengthy review of the history of neuroscience. Over about a fifth of the book, he discusses the early days of neuroscience, rooted in electrophysiology and competition between the most prominent scientists of the day, whom Koob portrays as egotistical, "controlling," and capable of the "despicable act" of falling prey to others' unscientific persuasion. These forerunners of the field decided almost cursorily, that neurons, which make up a mere 10% of the brain, were the only important cells. It was neurons that were thought to be the power behind thinking, learning, moving, and even unconscious body function. Meanwhile, the glia, which comprised the other 90% of the brain, were thought to serve roles as unimportant as holding neurons together, cushioning them during movement, or tidying up the brain space. As a result of this "Neuron Doctrine," scientists focused their attention to neurons and left glia unstudied for over 60 years.

After discussing the historical reasons for the neglect of glia in neuroscience, Koob provides an overview of glial structure and function. In particular, the most abundant type of glial cell, the astrocyte, is highlighted as the true center of the brain. In the metaphor developed by Koob, the astrocytes are cities which are connected and supported by the neuronal highways. As he puts it another way, "Neurons have no reason to exist except to support astrocytes. Mature neurons cannot function alone, whereas mature astrocytes have no difficulty existing without neurons." Like neurons, astrocytes also communicate with one another through electrochemical signaling. Waves of calcium ions, flowing in and out of astrocytes, serve to process, integrate, and transmit information from one astrocyte to the next. Since astrocytes ultimately monitor neural synapses, releasing the calcium waves and absorbing neurotransmitters, this activity implies that astrocytes directly modulate synaptic activity and may even contribute to long-term potentiation in synapses in the form of memory. Perhaps most remarkably, the random nature of the astrocytes' calcium waves suggests that astrocytes, not neurons, are the source of high-level cognition, thought, and even creativity.

Following his explanation of astrocyte function, Koob turns his attention to a host of recent studies, which have implicated astrocytes and other glia in critical functions from providing immune defense to regulating blood flow to aiding in myelination of neurons. Each chapter provides a different topic, and over the last third of the book, Koob spans subjects such as learning and memory, dreaming, neurodegenerative diseases, traumatic brain injuries, and brain tumors. Despite being neglected in research for almost a century, glia have now been shown to play an important role in all these areas of neuroscience. Throughout the latter portion of the book, Koob provides several interesting anecdotes of the studies which first identified the importance of glia in these capacities. The brains of canaries learning to sing even in adulthood showed the generation of new neural cells, notably both neurons and glia, in the areas of the brain responsible for song learning. In the 1950s, scientists studied the brain of Albert Einstein, a man renowned for his imaginative thought, which eventually resulted in arguably the most important discovery in modern physics. As Koob puts it more straightforwardly, "this is the kind of man who used his glia." Not surprisingly, Einstein had significantly greater number of astrocytes in his left parietal cortex, an area associated with higher thought, mathematics, and spatial learning. Such stories and more abound in Koob's final chapters, and all of them serve to support his overarching hypothesis that it is glia, not neurons, which act as the intelligent centers of our brains by modulating neuron communication at the synapse. It is glia, thanks to their random calcium waves, which are responsible for higher cognition and the random thought that distinguishes human beings from our less sophisticated animal counterparts. Overall, Koob argues that the recent discovery of glial importance is one that should be expanded in future research.

Review Opinion

Overall, reading this book was mostly enjoyable, and Koob provides an abundance of interesting historical anecdotes, a sprinkling of popular culture references, and a fair amount of, albeit sometimes overstated, humor. At its heart this book is a well-woven collection of stories surrounding neuroscience, both in the early days of the study and in more recent research surrounding glia. By structuring these stories around a larger story of the rise of glia, Koob is able to craft a well-organized summary that guides the reader through his proposal. Koob also does all this without requiring much, if any, of a previous knowledge of neuroscience from the reader. Perhaps the book's greatest strength, though, is its unique premise. It is true that glia have long been neglected as a critical brain component, and Koob provides many ideas that indicate this has been an unfortunate mistake, as glia have now been implicated in several of the most important areas of neuroscience.

Especially for such a unique hypothesis, however, it is expected that Koob would support his claims with plenty of evidence. Unfortunately, this is not the case. Too much of the book is consumed by a description of the history of neuroscience, which provides no evidence for the importance of glia and instead is read as an almost-angry rant in which Koob expresses his disdain for the oversight of neuroscience's pioneers and their abandonment of glial research. Even in the latter half of the book, when Koob describes the function of astrocytes and their role in thought, most of his claims are backed by indirect evidence and seem to be largely speculation. For instance, Koob compares the ratio of astrocytes to neurons in a spectrum of animals, from the primitive earthworm to the mouse to the human being and notes that more intelligent animals have a higher ratio of astrocytes to neurons. Still, this is hardly robust support for his claim that it is this ratio that creates our most complex behavior, the generation of thought and creativity. Although this is certainly an interesting statement, Koob fails to adequately validate it over and over again throughout the book. He fails to propose any sort of hypothetical mechanism for this creation of thought beyond purely random calcium flux, and ultimately, the book's title, "The Root of Thought," becomes misrepresentative of the information Koob is able to objectively present. The central idea that neurons exist to support glia and not vice versa is also never explained with the results of any modern research. On the whole, it seems the conclusions Koob draws are extrapolated far beyond the results of any of the scientific studies he does cite.

Koob's passion for his hypothesis is evident throughout the book, though his style of expression creates something that is part neuroscience and part outburst against the scientists who left glia in the dust for so long. Koob's anger over this historical circumstance fails to consider the fact that though biased by the popular topic of electricity, early neuroscientists did not sinisterly or intentionally misguide the future of their field for half a century. Unfortunately, this is the impression given to the reader, and that detracts greatly from the overall argument Koob tries to make.

Stylistically, Koob's writing also has several limitations. As other reviewers have mentioned, his metaphors are overdone and at times borderline absurd. The book also lacks some of the finer elements of writing and even some basic proofreading, indicating that Koob is first and foremost a scientist and not a writer.

For the casual reader, the aforementioned shortcomings may not undermine the unique hypothesis Koob presents and his engaging explanation of glia's importance through historical and modern anecdotes. To such a reader, the book would be recommended as an interesting survey of neuroscience with a unique focus on glia. However, to anyone trained in science or critical analysis, Koob's evidence simply does not fully support his hypothesis, and the book is disappointing as an argument at large. For now, readers may have to wait for a more scientifically supported explanation of the critical role of glia, which is certainly an interesting premise worth further exploration.

I am a "brain/mind enthusiast". I am a science teacher of 13 years whose main study was in physics, but who also enjoyed biology. I am just coming around to secular study of A&P.

The large 2-star review was extensive and detailed. The reviewer felt the author premature in making many of his conclusions without more evidence to support them.

I say, THAT is the only way advancement is ever made: someone looking at the status quo with curious doubt, who sets up initial experiments, records results, and makes an "erroneous" claim.

Before I read this book, I thought the brain was only composed of neurons; I didn't have human anatomy/physiology, opting for Zo and Botany classes in general to complete my degree. Besides, nothing is ever said "commercially" about any other cell. I found it shocking that the statement "only 10% of our brain is used" was based on the ratio of glial to neural cells; shouldn't we know by now that Nature doesn't do anything without purpose? Why would 90% of our brain be "inactive"? I also found it shocking that "our" reliance on neurons as the progenitors of thought is based on an earlier-than-19th-century paradigm of electrical stimuli.

Why shouldn't the main function, THOUGHT, be carried out in the main structure, GLIAL cells?

To this, I tell all doubting researchers of academia: DUH! Get out of your boneheaded paradigm and use a little imagination. It's not hard to put it together.

Read the book. It's hilarious at the right times, too.

A gem that should be read by everyone.

The Root of Thought is Andrew Koob's book about the emerging research suggesting that the glial cells in our brain ("the other 90% of our brain") may serve more of a vital role in thought processing and other brain functions than was ever previously understood. Koob is a brain scientist, and it is clear from the very beginning of his work that it was written by a researcher and not someone more classically trained in literature. The book seems to have been written without an intended audience in mind because it is this reviewer's opinion that it is not nearly accessible enough to be enjoyed by the casual reader yet oversimplified for the neuroscience aficionado. As a reader, it was difficult to become engaged with the text because it seemed to assume a fair bit of neuroscience fluency that the average individual does not possess. As a college biomedical engineering major I found myself frustrated by a lack of detail at times and at other times inundated with references to brain physiology that were unfamiliar to me. I did not find the book to be an enjoyable read; however, the science upon which the book is written is fascinating.

The first quarter of the book is devoted to the history of brain research from the beginnings of electrophysiology up until the recent decades when the importance of glia has begun to emerge. It summarizes that glial cells were thought to merely be insulators for neurons without serving any other functional purpose, and that the only important cells in the brain were neurons (Neuron Doctrine). Consequently, the research conducted over the nearly 100 years that followed focused almost exclusively on neurons. These three history chapters could (and probably should) be condensed into one short chapter that gives the reader a basic understanding of the Neuron Doctrine and explains why science is only just beginning to understand the importance of glial cells. The history section as it is currently written is overly drawn out, references entirely too many studies that most readers are surely unfamiliar with, and includes several unnecessary and inappropriate personal references from the author revealing his frustrations with the pioneering brain scientists responsible for the establishment of the Neuron Doctrine.

The subsequent chapters discuss the functional mechanism of glia (more specifically astrocytes), their possible role in intelligence and thought generation, their connection to dreams, and their potential to be used to treat brain diseases. These sections are better than the first, but require too much effort by the reader to identify conclusions and determine what is important.

Astrocytes communicate to themselves as well as neurons using calcium waves, and it is hypothesized that these calcium waves are the roots of our thoughts. The calcium waves may be the mechanism by which we store information in our cortex and how we can think about what we have experienced. Astrocytes help to form neuronal synapses which help to increase intelligence by increasing the speed at which we can process information, but astrocytes are also capable of spontaneous firing without neurons, which may be the source of inspiration and imagination. It has been shown that having a higher glia-to-neuron ratio correlates with higher intelligence, and since humans have the highest ratio of any animal, this may explain our intellectual dominance over the animal kingdom. Koob also mentions that "Einstein had a [significantly] higher astrocyte-to-neuron ratio in the area of the left parietal cortex" as compared to "normal" brains, which may explain his increased ability in mathematics and spatial thinking (104).

Astrocytes are thought to be more active at night, doing most of their regeneration during this time. Koob suggests "the rapid eye movements seen in REM sleep could be glia experimenting with the neuronal firing to make sure their connections are solid" (112). The astrocytes respond to a day's worth of sensory input by growing new astrocytes in the regions that were most commonly used. It is thought that this glial activation during the night may be the source of dreaming, and since it is easier to instigate calcium waves in cells that have been previously activated, it seems that our dreams are the direct result of our recent experiences.

Another key function of astrocytes is the maintenance of neurons, mainly in the form of removing cellular waste such as glutamate. There is evidence to suggest that several of the common brain degenerative diseases may be the indirect result of gliadegeneration. It is hypothesized that with fewer astrocytes available to remove the cellular waste, the neurons themselves begin to degenerate. Additionally, it is thought that astrocytes serve to prevent secondary neurodegeneration following a head injury. Much of the research regarding brain injury focusses on the possibility of injecting astrocytes into the damaged brain area to see it will help to maintain the health of the neurons. Koob states, "In the event of a gunshot wound to the head, astrocyte therapy may be the only avenue to regrow areas of the brain" (137).

As was mentioned in a previous review, most of what Koob discusses in this book is purely speculation at this point as the research in this field is only in its infancy. I question whether Koob is justified in making several of the claims that he does regarding the importance of glia without more concrete studies to support such statements. It appears he may be falling into a similar trap as the Neuron Doctrine by focusing so exclusively on glia. The reader is cautioned not to take Koob's writing as fact, but merely as speculation as to the potential functions of glia. Overall, the science that Koob discusses in his book is really quite fascinating, which makes it a shame that it is written so poorly. The average reader with an interest in the subject should pursue an abbreviated outline of the text that summarizes the interesting points rather than the text itself as it is not accessible to those without at least a minor familiarity with the subject matter.