Who's in Charge?
eBook - ePub

Who's in Charge?

Michael S. Gazzaniga

Share book
  1. 272 pages
  2. English
  3. ePUB (mobile friendly)
  4. Available on iOS & Android
eBook - ePub

Who's in Charge?

Michael S. Gazzaniga

Book details
Book preview
Table of contents
Citations

About This Book

"Big questions are Gazzaniga's stock in trade."
— New York Times

"Gazzaniga is one of the most brilliant experimental neuroscientists in the world."
—Tom Wolfe

"Gazzaniga stands as a giant among neuroscientists, for both the quality of his research and his ability to communicate it to a general public with infectious enthusiasm."
—Robert Bazell, Chief Science Correspondent, NBC News

The author of Human, Michael S. Gazzaniga has been called the "father of cognitive neuroscience." In his remarkable book, Who's in Charge?, he makes a powerful and provocative argument that counters the common wisdom that our lives are wholly determined by physical processes we cannot control. His well-reasoned case against the idea that we live in a "determined" world is fascinating and liberating, solidifying his place among the likes of Oliver Sacks, Antonio Damasio, V.S. Ramachandran, and other bestselling science authors exploring the mysteries of the human brain.

Frequently asked questions

How do I cancel my subscription?
Simply head over to the account section in settings and click on “Cancel Subscription” - it’s as simple as that. After you cancel, your membership will stay active for the remainder of the time you’ve paid for. Learn more here.
Can/how do I download books?
At the moment all of our mobile-responsive ePub books are available to download via the app. Most of our PDFs are also available to download and we're working on making the final remaining ones downloadable now. Learn more here.
What is the difference between the pricing plans?
Both plans give you full access to the library and all of Perlego’s features. The only differences are the price and subscription period: With the annual plan you’ll save around 30% compared to 12 months on the monthly plan.
What is Perlego?
We are an online textbook subscription service, where you can get access to an entire online library for less than the price of a single book per month. With over 1 million books across 1000+ topics, we’ve got you covered! Learn more here.
Do you support text-to-speech?
Look out for the read-aloud symbol on your next book to see if you can listen to it. The read-aloud tool reads text aloud for you, highlighting the text as it is being read. You can pause it, speed it up and slow it down. Learn more here.
Is Who's in Charge? an online PDF/ePUB?
Yes, you can access Who's in Charge? by Michael S. Gazzaniga in PDF and/or ePUB format, as well as other popular books in Biological Sciences & Neuroscience. We have over one million books available in our catalogue for you to explore.

Information

Publisher
Ecco
Year
2011
ISBN
9780062096838
Chapter One
The Way We Are
THERE IS THIS PUZZLE ABOUT EVERYDAY LIFE: WE ALL FEEL like unified conscious agents acting with self-purpose, and we are free to make choices of almost any kind. At the same time everyone realizes we are machines, albeit biological machines, and that the physical laws of the universe apply to both kinds of machines, artificial and human. Are both kinds of machines as completely determined as Einstein, who did not believe in free will, said, or are we free to choose as we wish?
Richard Dawkins represents the enlightened science view that we are all determined mechanistic machines and immediately points out an implication. Why do we punish people who engage in antisocial behavior? Why don’t we simply view them as people who need to be fixed? After all, he argues, if our car stalls and fails us, we don’t beat it up and kick it. We fix it.
Switch out the car for a horse that bucked you off. Now what do we do? The thought of a good poke does pop into the mind more than a trip to the barn for repairs. Something about animate flesh calls upon a seemingly vibrant set of responses that are part of us humans and pull along with them a host of feelings and values and goals and intentions and all those human mental states. In short, there is something about the way we are built, and presumably our brains, that appears to be governing a lot of our everyday behavior and cognition. We seem to have a lot of complexity in our makeup. Our very own brain machine runs on its own steam, even though we think we are in charge. Now that is a puzzle.
Our brains are a vastly parallel and distributed system, each with a gazillion decision-making points and centers of integration. The 24/7 brain never stops managing our thoughts, desires, and bodies. The millions of networks are a sea of forces, not single soldiers waiting for the commander to speak. It is also a determined system, not a freewheeling cowboy acting outside the physical, chemical forces that fill up our universe. And yet, these modern-day facts do not in the least convince us there is not a central “you,” a “self” calling the shots in each of us. Again, that is the puzzle, and our task is to try and understand how it all might work.
The accomplishments of the human brain are one good reason we are convinced of our central and purposeful self. The modern technology and know-how of humans is so crazy-amazing that a monkey with a neural implant in North Carolina can be hooked up to the Internet, and, when stimulated, the firing of his neurons can control the movements of a robot in Japan. Not only that, the nerve impulse travels to Japan faster than it can travel to that monkey’s own leg! Closer to home, take a look at your dinner. If you are lucky, tonight you might have a locally grown salad with sliced pears from Chile and an amazingly tasty gorgonzola from Italy, a lamb chop from New Zealand, roasted potatoes from Idaho, and red wine from France. How many different creative and innovative people cooperated in both scenarios to pull them off? Tons. From the person who first thought about growing his own food, and the one who thought the old grape juice was a bit interesting, to Leonardo, who first drew a flying machine, to the person who took the first bite of that moldy-looking cheese and thought they had a winner, to the many scientists, engineers, software designers, farmers, ranchers, vintners, transporters, retail dealers, and cooks who contributed. Nowhere in the animal kingdom does such creativity or cooperation between unrelated individuals exist. Perhaps even more amazing is that there are people who do not see much difference in the abilities of humans and that of other animals. In fact, they are pretty sure that their darling dog with the big, sad eyes is just a hair’s breadth away from getting his self-help article published: “How to Manipulate Your Human Housemate Without Even Getting Off the Couch.”
Humans have spread across the world and live in hugely varying environments. Meanwhile, our closest living relatives, the chimps, are endangered. You have to ask why humans have been so wildly successful, while our closest living relations are barely hanging on. We can solve problems that no other animal can solve. The only possible answer is that this came about because we have something that they do not. Yet we find this difficult to accept. As we are perched here at the beginning of the twenty-first century, we have more information to help answer some of these questions, information that was not available to the curious and inquiring minds of the past. And curious were those who have gone before us: Human interest in what and who we are is at least as old as history. Etched in the walls of the seventh-century B.C. Temple of Apollo in Delphi is the advice KNOW THYSELF. Man has always been intrigued with the nature of the mind, self, and the human condition. Where does this curiosity come from? That is not what your dog is thinking about on the couch.
Today, neuroscientists are exploring the brain by poking it, recording from it, stimulating it, analyzing it, and comparing it with those of other animals. Some of its mysteries have been revealed and theories abound. Before we get all impressed with our modern selves, we need to keep our egos in check. Hippocrates, in the fifth century B.C., wrote as if he were a modern neuroscientist: “Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations. And by this . . . we acquire wisdom and knowledge, and see and hear, and know what are foul and what are fair, what are bad and what are good, what are sweet and what unsavory. . . . And by the same organ we become mad and delirious, and fears and terrors assail us. . . . .”1 His mechanisms of action were sketchy, but he had the principles down.
So I guess that leaves science to explain the mechanisms, and in doing so we best take the advice of Sherlock Holmes, who was known for his scientific method: “The difficulty is to detach the framework of fact—of absolute undeniable fact—from the embellishments of theorists and reporters. Then, having established ourselves upon this sound basis, it is our duty to see what inferences may be drawn and what are the special points upon which the whole mystery turns.”2
This impulse, just nothing but the facts, is a way to start solving a puzzle, and early brain scientists started in that spirit. What is this thing? Let’s get a corpse, open up the skull, and take a look. Let’s make holes in it. Let’s study people with stroke. Let’s try to record electrical signals from it. Let’s see how it hooks itself up during development. As you will see, those are the sort of simple questions that motivated early scientists and still motivate many today. As I go through our story, however, it will become evident that without actually studying the behavior of organisms or knowing what our evolved mental systems were selected to do, settling the question of “self” versus machine becomes a hopeless goal. As the great brain scientist David Marr observed, there is no way to understand how a wing of a bird works by studying its feathers. As the facts accumulate, we need to give them functional context and then examine how that context may, in fact, constrain the underlying elements that generate the function. Let’s begin.
Brain Development
Something short and snappy-sounding like “brain development” should be simple to study and understand, but in humans development ranges far; it takes in not only the neural, but also the molecular, and not only cognitive change over time, but also the influence of the external world. It turns out not to be simple at all: Oftentimes detaching the framework of fact from the theorizing is a long and arduous process with many detours, and such was the fate of unraveling the basics of how the brain develops and works.
Equipotentiality
The early twentieth century had suffered such a detour, the repercussions of which, both in the scientific and lay worlds, are still plaguing us in the form of the nature-versus-nurture question. In 1948, at my alma mater, Dartmouth College, two of Canada’s and America’s great psychologists, Karl Lashley and Donald Hebb, came together to discuss the following question: Is the brain a blank slate and largely what we call today “plastic,” or does the brain come with constraints and is it somewhat determined by its structure?
At the time, the blank slate theory had reigned for the previous twenty years or so, and Lashley had been one of its early proponents. He was one of the first researchers to employ physiological and analytical methods to study brain mechanisms and intelligence in animals; he had carefully induced damage to the cerebral cortex in rats and quantified it, measuring their behavior before and after he made the lesions. While he found that the amount of cortical tissue he removed affected learning and memory, the location of it did not. This convinced him that the loss of skills was related to the volume of excised cortex rather than its location. He did not think that a specific lesion would result in the loss of a specific ability. He proposed the principles of mass action (the action of the brain as a whole determines its performance) and equipotentiality (any part of the brain can carry out a given task, thus no specialization).3
Lashley, while doing his graduate studies, had come under the influence, and became a good friend, of John Watson, the director of the psychological laboratory at Johns Hopkins University. Watson, an outspoken behaviorist and “blank-slater” famously said in 1930, “Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select—doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors.”4 Lashley’s principles of mass action and equipotentiality fit well within the framework of behaviorism.
More evidence for this idea of equipotentiality came from one of the first developmental neurobiologists, Paul Weiss. He also thought that the brain was not that specific in its development and coined the famous phrase, “function precedes form,”5 based on the results of his experiments in which he grafted an additional limb onto a newt, an amphibian in the salamander family. The question was, Did the nerves grow out to the limb specifically or did the nerves grow out randomly and then through the use of the limb become adapted to be limb neurons? He had found that transplanted salamander limbs would become innervated and capable of learning movement that was fully coordinated and synchronized with the adjacent limb. Roger Sperry, Weiss’s student and later my mentor, summarized Weiss’s widely accepted resonance principle as “a scheme in which the growth of synaptic connections was conceived to be completely nonselective, diffuse, and universal in downstream contacts.”6 So at the time it was thought that “anything went” in the nervous system—(neuron to neuron) there was no structured system. Lashley started it, the behaviorists pushed it, and the greatest zoologist of the time agreed.
Neuronal Connections and Neurospecificity
But Donald Hebb was not convinced. Although he had studied with Lashley, he was an independent thinker and started to develop his own model. He began to think that it was how specific neuronal connections worked that was important and shied away from the ideas of mass action and equipotentiality. He had already rejected the ideas of Ivan Pavlov, the great Russian physiologist, who had seen the brain as one big reflex arc. He was convinced that the operations of the brain explained behavior, and that psychology and biology of an organism could not be separated, a well-accepted idea now, but unusual at the time. Contrary to the behaviorists who thought that the brain merely reacted to stimuli, he recognized that the brain was always running, even when there was no stimulus present. He strove for a framework that captured that fact with the limited data on brain function that was available in the 1940s.
Hebb set about to postulate how this occurred based on his research. The death knell for strict behaviorism and the return to an earlier idea of neural connectivity’s being of great importance came in 1949 with the publication of Hebb’s book The Organization of Behavior: A Neuropsychological Theory. He wrote: “When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.”7 Colloquially this is known in neuroscience as “Neurons that fire together, wire together” and forms the basis of Hebb’s proposals for learning and memory. He proposed that groups of neurons that fire together make up what he called a cell assembly. Neurons in the assembly can continue to fire after an event that has triggered them, and he suggested that this persistence is a form of memory and that thinking is the sequential activation of assemblies. In short, Hebb’s ideas pointed out the centrality of the idea of the importance of connectivity. It remains a central topic of study in neuroscience today.
Hebb focused his attention on neural networks and how they might work to learn information. While he did not focus on how those networks came to be, one of the implications of his theory is that thinking affects the development of the brain. In fact, in earlier experiments on rats published in 1947, Hebb had shown that experience can affect learning.8 Hebb understood that his theory would undergo revision as more discoveries about brain mechanisms were made, but his insistence on combining biology with psychology marked the path that in little more than a decade led to the new field of neuroscience.
It was beginning to be understood that once information was learned and stored, specific brain areas had used that information in different, particular ways. The question remained, however, how did the networks form? In short, how does the brain develop?
The foundational work that became the backbone of modern neuroscience and emphasized the importance of neurospecificity was done by Paul Weiss’s student Roger Sperry. How the connectivity, or wiring, took place was the question that fascinated him. He was skeptical of Weiss’s explanation of nerve growth, where functional activity played a predominant role in the formation of neural circuitry. In 1938, the year that he began his research, other rumblings against the doctrine of the functional plasticity of the nervous system came from two Johns Hopkins Medical School physicians, Frank R. Ford and Barnes Woodall, when they recounted their experiences with clinical patients whose disorders of function, after nerve regeneration, persisted for years without improvement.9 Sperry set out to investigate functional plasticity in rats by seeing what the behavior effects were of changing nerve connections. He switched the nerve connections between the opposing flexor and extensor muscles in each rat’s hind foot, which resulted in reversing the movement of the ankle, to see if the animals could learn to move the foot correctly, as was predicted by Weiss’s functionalist view. He was surprised to find that the rats never adjusted, even after long hours of training.10 For example, while climbing a ladder their foot went up when it should have gone down and vice versa. He had assumed new circuits would be established and normal function would return, but it turned out that motor neurons were not interchangeable. Next he tried the sensory system, transposing the skin nerves from one foot to another. Once again the rats continued to have false reference sensations: when the right foot was shocked, they would lift the left one; when the right foot had a sore, they would lick the left one.11 Both their motor and sensory systems lacked plasticity. Unfortunately, Weiss had made a poor choice in picking the salamander to use as a model for the human in his experiments; regeneration of the nervous system is exhibited only by the lower vertebrates, that is, fishes, frogs, and salamanders. Sperry was returning to the idea that a type of chemotaxis regulated the growth and termination of nerve fibers, first proposed early in the twentieth century by one of the greatest neuroscientists of all time, Santiago Ramón y Cajal.
Sperry thought that the growth of nerve circuits was the result of a highly specific genetic coding for nerve contacts. He performed dozens of clever experiments to make his point. In one, he simply took a frog and surgically turned the eye upside down. Afterwards, when the frog was shown a fly, his tongue went for it in the opposite direction. Even after the eye had been in this position for months, the frog continued to search for it in the wrong direction. There was specificity to the system: it was not plastic and could not adapt. He then took a goldfish and cut parts of the retina. As the nerves regenerated, he watched where they would grow in the part of the midbrain that receives input from the eyes, the optic tectum. It turned out that they would grow very specifically. If they were growing from the back of the retina, they would grow to the front of the tectum, and if they were from the front of the retina, they grew to the back of the tectum. In other words, there was a specific location that they grew to, no matter their starting position. Sperry concluded that “Whenever central fiber systems were disconnected and transplanted or just scrambled by rough surgical section, regrowth always led to orderly functional recovery and under conditions that precluded re-educative adjustments.”12 A bit later in the 1960s, nerve growth was actually observed and photographed, revealing that the grow...

Table of contents