Moheb Costandi - Neuroplasticity

Neuroplasticity

The MIT Press Essential Knowledge Series

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Neuroplasticity

Moheb Costandi

The MIT Press Cambridge, Massachusetts London, England

2016 Massachusetts Institute of Technology

All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher.

Library of Congress Cataloging-in-Publication Data

Names: Costandi, Moheb.

Title: Neuroplasticity / Moheb Costandi.

Description: Cambridge, MA : The MIT Press, 2016. | Series: The MIT Press

essential knowledge series | Includes bibliographical references and index.

Identifiers: LCCN 2016002722 | ISBN 9780262529334 (pbk. : alk. paper)

Subjects: LCSH: Neuroplasticity. | Neural transmission. | Nervous

systemPhysiology.

Classification: LCC QP364.5 .C67 2016 | DDC 573.854dc23 LC record available at http://lccn.loc.gov/2016002722 ISBN: 978-0-262-52933-4

EPUB 3.0

Contents

Series Foreword

The MIT Press Essential Knowledge series offers accessible, concise, beautifully produced pocket-size books on topics of current interest. Written by leading thinkers, the books in this series deliver expert overviews of subjects that range from the cultural and the historical to the scientific and the technical.

In todays era of instant information gratification, we have ready access to opinions, rationalizations, and superficial descriptions. Much harder to come by is the foundational knowledge that informs a principled understanding of the world. Essential Knowledge books fill that need. Synthesizing specialized subject matter for nonspecialists and engaging critical topics through fundamentals, each of these compact volumes offers readers a point of access to complex ideas.

Bruce Tidor

Professor of Biological Engineering and Computer Science

Massachusetts Institute of Technology

Preface

In recent years, researchers have made major advances in their understanding of how the brain works. Neuroscience offers both promises and perils, so public interest in it has grown enormously, because of the potential and promises that it offers, and one neuroscientific concept in particular has captured the public imagination: neuroplasticity, or change in the nervous system.

Sixty years ago, the idea that nervous tissue can change was anathema to neuroscience. It was widely believed that the mature brain is a fixed structure and, therefore, that you cant teach an old dog new tricks. This dogma has since been overturned by a huge body of research which shows not only that the brain can change, but also that it changes continuously throughout life, in one way or another, in response to everything we do and every experience we have.

Neuroplasticity is a catch-all term referring to the many different ways in which the nervous system can change. It is ill-defined by neuroscientists, who use it to describe a wide variety of phenomena. Among the general public, the concept is generally misunderstood, and misconceptions about what neuroplasticity is, and what it is capable of, are rife.

This book summarizes essential knowledge about neuroplasticity for the general reader, focusing on key experimental findings and the methods and technologies used to obtain them, and on how our thinking about the brain has evolved over time.

Each chapter of the book is devoted to research into one particular mode of neuroplasticity. After offering a historical perspective, it describes the changes that occur during brain development; the changes that occur in the brains of blind and deaf people; the mechanisms of synaptic plasticity that underlie learning; the formation of new cells in the adult brain; how different types of training, such as learning to play a musical instrument or speak a foreign language, alter the brain; how neuroplasticity goes awry in addiction and pain states; and the key brain changes associated with different stages of life. The concluding chapter summarizes key points, describes several newly discovered forms of plasticity, and explores some of the many questions that remain to be answered.

The mechanisms of neuroplasticity are so many, and so diverse, that one could not hope to cover the whole subject in such a small book. Nevertheless, this volume should give the reader a good overview of what we know about neuroplasticity, as well as a solid understanding of some key neuroscientific principles, knowledge of important historical developments in the field, and some insight into the scientific process.

1 INTRODUCTION

If you query Google about rewiring your brain, its autocomplete function will give you a list of the most popular search terms using that phrase. You can, according to the results of such a search, rewire your brain for love and for happiness, to become more successful at work, and even to find meaning in your life. Scrolling down the search results brings up yet more options: rewire your brain to think positively, cultivate self-confidence, sleep better, and avoid procrastination. If the Internet is to be believed, you can rewire your brain to improve just about any aspect of your behavior, and so the power to transform your life lies in your ability to consciously change that 1.4-kilogram lump of meat inside your head.

But what does rewiring your brain actually mean? It refers to the concept of neuroplasticity, a very loosely defined term that simply means some kind of change in the nervous system. Just 50 years ago, the idea that the adult brain can change in any way was heretical. Researchers accepted that the immature brain is malleable, but also believed that it gradually hardens, like clay poured into a mold, into a permanently fixed structure by the time childhood has ended. It was also believed that we are born with all the brain cells we will ever have, that the brain is incapable of regenerating itself, and, therefore, that any damage or injuries it sustains cannot be fixed.

In fact, nothing could be further from the truth. The adult brain is not only capable of changing, but it does so continuously throughout life, in response to everything we do and every experience we have. Nervous systems evolved to enable us to adapt to the environment and determine the best course of action in any given situation, based on what has been learned from past experiences. This is the case not just for humans, but for all organisms that have a nervous system. That is to say, nervous systems evolved to change, and so neuroplasticity is an intrinsic and fundamental property of all nervous systems.

The adult brain is not only capable of changing, but it does so continuously throughout life, in response to everything we do and every experience we have.