Neuropedia: A Brief Compendium of Brain Phenomena

Neuropedia

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Preface

Mientras nuestro cerebro sea un arcano, el universo, reflejo de su estructura, será un arcano también.

(As long as our brain is a mystery, the universe, the reflection of the structure of the brain, will also be a mystery.)

—SANTIAGO RAMÓN Y CAJAL (1922)¹

The words of pioneering neuroscientist Santiago Ramón y Cajal (1852–1934) reflect the thoughts of many scientists and philosophers who over the centuries have tried to unravel the workings of the brain. Using the most advanced tools and technologies available in their time, these men and women have figuratively and literally probed the brain, seeking treatments and cures for neurological disease, and searched for the underlying cause of what makes us human.

Scientists take many different pathways to the field of brain research and come from diverse academic backgrounds. A neuroscientist may enter the field with a medical degree or a doctoral degree in neuroscience, biology, chemistry, physics, bioengineering, physiology, or a related field. Others approach neuroscience from outside the natural or physical sciences, for example, graduating from college with a major in music or philosophy. For me, neuroscience was not on my list of career aspirations until my last years of college. As a kid, I grew up in Los Angeles (California), Kuala Lumpur (Malaysia), and Kobe (Japan). Whether it was riding my bike along the concrete and asphalt streets of Southern California, searching the monsoon drains surrounding my house in Southeast Asia, or climbing the hills behind my school in Kobe, I tried to get outside as much as possible. Perhaps my love of the outdoors is why my high school career aptitude test determined that I was best suited to become a forester.

Both of my parents were teachers and, although neither of them had any background in science, they always encouraged me to follow my interests regardless of the subject. In high school, my interests were mainly sports. But during my senior year of high school, I took a marine biology class where students were taught about the invertebrates, birds, fish, and mammals that live in and around the ocean. This class sparked my curiosity about nature and motivated me to learn more about marine life. On weekends, I would drive thirty minutes to the beach in Los Angeles—not to sit on the sand, but to explore the tide pools. Each day there revealed something new and unexpected. I spent hours turning over rocks (and carefully putting them back in place) to see the invertebrate life that lived hidden at the intersection of sand and sea. These days I check the tide tables and get out to the tide pools of Puget Sound several times a year.

When I entered college at the University of California, Los Angeles (UCLA), in 1976, I thought that I would become an oceanographer. My favorite course, invertebrate biology, included trips to the bays around Los Angeles, where students would board a boat and dredge the ocean floor for moon snails, sea cucumbers, worms, and other animals. We would take our catch back to the lab to study our specimens. During class, the professor entertained students with stories of how he spent his research time studying shrimp in warm South Pacific Ocean waters. This sounded like a great career: to get paid for something I would do for free.

My academic pathway took a new direction at the start of my junior year at UCLA when I enrolled in an introductory psychology class. The instructor of the class was Dr. John Liebeskind (1935–1997), who introduced himself as a physiological psychologist but these days would be called a neuroscientist. I didn’t know it at the time, but Dr. Liebeskind was an innovative researcher who was making important discoveries about the brain’s own pain inhibitory system. After one lecture about the brain, Dr. Liebeskind invited students to follow him back to his lab for a short tour. I joined a small group of three or four students who took him up on his offer and followed the professor to his lab in the basement of the psychology building. At the end of the brief tour, Dr. Liebeskind said that any of us students could join his lab if we showed up the following day. I was the only student who returned the next day and was put to work quickly by the graduate students and postdoctoral researchers. There was no undergraduate neuroscience major at UCLA until 1992, so instead I switched my major to psychobiology. I worked in the Liebeskind lab as a volunteer undergraduate researcher until I graduated in 1980 with my bachelor’s degree in psychobiology. I then went on to pursue a master’s degree and a doctorate degree before taking a research position at the National Institutes of Health in Bethesda, Maryland, where I studied how the brain processes information related to touch and pain. I ultimately landed at the University of Washington, where I’ve been since 1991.

Neuroscience is important not only for researchers in labs and physicians in clinics, but for everyone. We are all likely to know someone affected by a neurological disorder. Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, depression, autism, stroke, schizophrenia—the list of neurological and psychiatric disorders goes on and on. These diseases take a tremendous emotional and economic toll on patients, family members, and caregivers. If we all knew more about the brain, perhaps we could better empathize with people affected by these disorders, reduce stigma attached to neurological diseases, and help people cope with their conditions. Beyond a better understanding of disease and disorders, the rapid advances in neuroscience make it imperative that everyone has a basic understanding of brain research to read articles in magazines, newspapers, and websites. It is difficult nowadays to read through popular media without seeing a story discussing the brain. Unfortunately, there is also a considerable amount of misinformation and misunderstanding about the brain. For example, a commonly held belief is that we use only a small portion of the brain; we actually use all of the brain. People with an understanding of brain research should be better equipped to analyze information in the media more critically. Further, new neuroscientific discoveries are impacting many segments of society, including our courtrooms, classrooms, and companies. Lawyers are using brain imaging to sway juries, teachers are looking to neuroscience for help to improve educational practices, and industry is developing new methods to enhance brain function. A neuroscientific-literate society will be better prepared to debate how such advances should be developed and disseminated.

In this book, I hope readers will enjoy learning about concepts, terms, structures, and people associated with the field of neuroscience. A complete catalog and detailed description of every neuroscientific phrase, brain structure, and influential neuroscientist is not possible in these pages, but I have tried to include entries that will stimulate your curiosity, help you become more familiar with neuroscience, and motivate you to learn more about the brain. Knowing neuroscientific facts and figures is only a small part of learning about the brain, and neuroscientists do not claim to fully understand how the brain works. Rather than just listing facts and figures, this book should provide you with a basic understanding of how neuroscientists have built theories about the brain and how the field has progressed over time.

Neuroscientific research has provided new treatments and even cures for some brain diseases, but effective therapies for many neurological diseases remain elusive, and the underlying mechanisms of some basic neurological functions (e.g., consciousness) are still not known. Don’t get me wrong. Researchers have made monumental progress in our understanding of the nervous system in health and disease and have provided exquisite detail about the anatomy and physiology of the nervous system, in thousands of papers published every year. These publications provide the pieces of the puzzle to a better understanding of ourselves and our place in nature—but many pieces are still missing.

I hope this book will answer some questions you have about the brain and nervous system. My intention is to open a window to the process of discovery that occurs in research laboratories every day. Answers to the mysteries about the brain are core to who we are as human beings.

Students often ask me what I like about being a neuroscientist. My response to this question is the same as why I turn over rocks in tide pools: you never know what you will find. Although we know an incredible amount about how the brain works, there is still so much more to learn. I hope Neuropedia will motivate you to turn over some rocks.

Neuropedia

A

ction Potential

Electrical signal that is the basic unit of communication for transmitting information throughout the nervous system. Capable of traveling at speeds faster than 250 mph, action potentials whisk electrochemical messages from neurons to muscles, organs, and other neurons to control our movements, emotions, perceptions, thoughts, and actions.

Particles in our body that are electrically charged are called ions. To set up an action potential, positively charged sodium ions and potassium ions and negatively charged chloride ions and protein molecules are arranged so there are different amounts of these ions on different