Foundations of behavioral neuroscience

524 Pages·122.996 MB·English

by  Carlson, Neil R

Foundations of Behavioral Neuroscience
Neil R. Carlson
Ninth Edition
ISBN 10: 1-292-02196-9
ISBN 13: 978-1-292-02196-6
Pearson Education Limited
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ISBN 10: 1-292-02196-9
ISBN 13: 978-1-292-02196-6
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A catalogue record for this book is available from the British Library
Printed in the United States of America
1112222332580360369371111757357311
P E A R S O N C U S T O M L I B R AR Y
Table of Contents
1. Origins of Behavioral Neuroscience
Neil R. Carlson 1
2. Structure and Functions of Cells of the Nervous System
Neil R. Carlson 21
3. Structure of the Nervous System
Neil R. Carlson 51
4. Psychopharmacology
Neil R. Carlson 81
5. Methods and Strategies of Research
Neil R. Carlson 107
6. Vision
Neil R. Carlson 135
7. Audition, the Body Senses, and the Chemical Senses
Neil R. Carlson 167
8. Sleep and Biological Rhythms
Neil R. Carlson 203
9. Reproductive Behavior
Neil R. Carlson 235
10. Emotion
Neil R. Carlson 267
11. Ingestive Behavior
Neil R. Carlson 293
12. Learning and Memory
Neil R. Carlson 331
13. Human Communication
Neil R. Carlson 371
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444503705735
14. Neurological Disorders
Neil R. Carlson 405
15. Autistic, Attention-Deficit, Stress, and Substance Abuse Disorders
Neil R. Carlson 437
16. Schizophrenia, Affective Disorders, and Anxiety Disorders
Neil R. Carlson 473
Index 505
II
OUTLINE
■ Understanding Human
Consciousness: A Physiological
Origins of Behavioral
Approach
Split Brains
Neuroscience
■ The Nature of Behavioral
Neuroscience
The Goals of Research
Biological Roots of Behavioral
Neuroscience
■ Natural Selection and
Evolution
Functionalism and the
Inheritance of Traits
Evolution of the Human Brain
■ Ethical Issues in Research
with Animals
■ Careers in Neuroscience
■ Strategies for Learning
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LEARNING OBJECTIVES N
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1. Describe the behavior of people with split brains and explain what 5. Describe the evolution of the human species.
study of this phenomenon contributes to our understanding of 6. Discuss the value of research with animals and ethical issues
self-awareness. concerning their care.
2. Describe the goals of scientific research. 7. Describe career opportunities in neuroscience.
3. Describe the biological roots of behavioral neuroscience.
4. Describe the role of natural selection in the evolution of behavioral
traits.
From Chapter 1 of Foundations of Behavioral Neuroscience, Ninth Edition. Neil R. Carlson. Copyright © 2014 by Pearson Education, Inc.
All rights reserved.
1
PROLOGUE | René’s Inspiration
René, a lonely and intelligent young man of eighteen years, had an imposing statue of Neptune rose in front of him, barring the way
secluded himself in Saint-Germain, a village to the west of Paris. He with his trident.
had recently suffered a nervous breakdown and chose the retreat René was delighted. He had heard about the hydraulically oper-
to recover. Even before coming to Saint-Germain, he had heard of ated mechanical organs and the moving statues, but he had not
the fabulous royal gardens built for Henri IV and Marie de Médicis, expected such realism. As he walked back toward the entrance to
and one sunny day he decided to visit them. The guard stopped the grotto, he saw the plates buried in the ground that controlled
him at the gate, but when he identified himself as a student at the the valves operating the machinery. He spent the rest of the after-
King’s School at La Flèche, he was permitted to enter. The gardens noon wandering through the grottoes, listening to the music and
consisted of a series of six large terraces overlooking the Seine, being entertained by the statues.
planted in the symmetrical, orderly fashion so loved by the French. During his stay in Saint-Germain, René visited the royal gardens
Grottoes were cut into the limestone hillside at the end of each again and again. He had been thinking about the relationship be-
terrace; René entered one of them. He heard eerie music accompa- tween the movements of animate and inanimate objects, which
nied by the gurgling of water but at first could see nothing in the had concerned philosophers for some time. He thought he saw in
darkness. As his eyes became accustomed to the gloom, he could the apparently purposeful, but obviously inanimate, movements of
make out a figure illuminated by a flickering torch. He approached the statues an answer to some important questions about the rela-
the figure, which he soon recognized as that of a young woman. tionship between the mind and the body. Even after he left Saint-
As he drew closer, he saw that she was actually a bronze statue Germain, René Descartes revisited the grottoes in his memory.
of Diana, bathing in a pool of water. Suddenly, the Greek goddess He even went so far as to name his daughter Francine after their
fled and hid behind a bronze rosebush. As René pursued her, designers, the Francini brothers of Florence.
T
he last frontier in this world—and perhaps the greatest one—lies within us. The human
nervous system makes possible all that we can do, all that we can know, and all that we
can experience. Its complexity is immense, and the task of studying it and understanding
it dwarfs all previous explorations our species has undertaken.
One of the most universal of all human characteristics is curiosity. We want to explain what
makes things happen. In ancient times, people believed that natural phenomena were caused by
animating spirits. All moving objects—animals, the wind and tides, the sun, moon, and stars—
were assumed to have spirits that caused them to move. For example, stones fell when they were
dropped because their animating spirits wanted to be reunited with Mother Earth. As our ances-
tors became more sophisticated and learned more about nature, they abandoned this approach
(which we call animism) in favor of physical explanations for inanimate moving objects. But they
still used spirits to explain human behavior.
From the earliest historical times, people have believed that they possessed something intan-
gible that animated them—a mind, a soul, or a spirit. This belief stems from the fact that each of
us is aware of our own existence. When we think or act, we feel as though something inside us is
thinking or deciding to act. But what is the nature of the human mind? We have physical bodies
with muscles that move them and sensory organs such as eyes and ears that perceive information
about the world around us. Within our bodies the nervous system plays a central role, receiving
information from the sensory organs and controlling the movements of the muscles. But what is
the mind, and what role does it play? Does it control the nervous system? Is it a part of the ner-
vous system? Is it physical and tangible, like the rest of the body, or is it a spirit that will always
remain hidden?
Behavioral neuroscientists take an empirical and practical approach to the study of human
nature. Most of us believe that the mind is a phenomenon produced by the workings of the ner-
vous system. We believe that once we understand the workings of the human body—especially
the workings of the nervous system—we will be able to explain how we perceive, how we think,
how we remember, and how we act. We will even be able to explain the nature of our own self-
awareness. Of course, we are far from understanding the workings of the nervous system, so only
time will tell whether this belief is justified.
2
Origins of Behavioral Neuroscience
Scientists and engineers have developed research methods that enable neuroscientists to study activity of
the human brain.
AJ Photo/Photo Researchers, Inc.
Understanding Human Consciousness:
A Physiological Approach
How can behavioral neuroscientists study human consciousness? First, let’s define our terms. The
word consciousness can be used to refer to a variety of concepts, including simple wakefulness. Thus,
a researcher may write about an experiment using “conscious rats,” referring to the fact that the rats
were awake and not anesthetized. By consciousness, I am referring to something else: the fact that we
humans are aware of—and can tell others about—our thoughts, perceptions, memories, and feelings.
We know that brain damage or drugs can profoundly affect consciousness. Because con-
sciousness can be altered by changes in the structure or chemistry of the brain, we may hypoth-
esize that consciousness is a physiological function, just as behavior is. We can even speculate
about the origins of this self-awareness. Consciousness and the ability to communicate seem to go
hand in hand. Our species, with its complex social structure and enormous capacity for learning,
is well served by our ability to communicate: to express intentions to one another and to make
requests of one another. Verbal communication makes cooperation possible and permits us to
establish customs and laws of behavior. Perhaps the evolution of this ability is what has given rise
to the phenomenon of consciousness. That is, our ability to send and receive messages with other
people enables us to send and receive our own messages inside our own heads—in other words,
to think and to be aware of our own existence. (See Figure 1.) FIGURE 1 Studying the Brain.
Will the human brain ever completely
Split Brains understand its own workings? A sixteenth-
century woodcut from the first edition of De
Studies of humans who have undergone a particular surgical procedure demonstrate dramatically humani corporis fabrica (On the Workings of
how disconnecting parts of the brain that are involved with perceptions from parts involved with the Human Body) by Andreas Vesalius.
verbal behavior also disconnects them from consciousness. These results suggest that the parts of National Library of Medicine.
the brain involved in verbal behavior may be the ones responsible for consciousness.
The surgical procedure is one that has been used for people with very severe epilepsy that cannot corpus callosum (core pus ka low
be controlled by drugs. In these people, nerve cells in one side of the brain become overactive, and sum) A large bundle of nerve fibers that
the overactivity is transmitted to the other side of the brain by a structure called the corpus callosum. connects corresponding parts of one side
of the brain with those of the other.
The corpus callosum is a large bundle of nerve fibers that connects corresponding parts of one side
of the brain with those of the other. Both sides of the brain then engage in wild activity and stimulate split-brain operation Brain surgery
that is occasionally performed to treat
each other, causing a generalized epileptic seizure. These seizures can occur many times each day,
a form of epilepsy; the surgeon cuts the
preventing the person from leading a normal life. Neurosurgeons discovered that cutting the corpus
corpus callosum, which connects the two
callosum (the split-brain operation) greatly reduced the frequency of the epileptic seizures. hemispheres of the brain.
3
Origins of Behavioral Neuroscience
Figure 2 shows a drawing of the split-brain operation. We see the brain
being sliced down the middle, from front to back, dividing it into its two sym-
Cutting device metrical halves. A “window” has been opened in the left side of the brain so
that we can see the corpus callosum being cut by the neurosurgeon’s special
knife. (See Figure 2.)
Sperry (1966) and Gazzaniga and his associates (Gazzaniga and LeDoux,
Top 1978; Gazzaniga, 2005) have studied these patients extensively. The largest part
of the brain consists of two symmetrical parts, called the cerebral hemispheres,
Corpus callosum
which receive sensory information from the opposite sides of the body. They
also control movements of the opposite sides. The corpus callosum enables the
two hemispheres to share information so that each side knows what the other
side is perceiving and doing. After the split-brain operation is performed, the
Front
two hemispheres are disconnected and operate independently. Their sensory
mechanisms, memories, and motor systems can no longer exchange informa-
tion. The effects of these disconnections are not obvious to the casual observer,
for the simple reason that only one hemisphere—in most people, the left—
controls speech. The right hemisphere of an epileptic person with a split brain
appears to be able to understand verbal instructions reasonably well, but it is
incapable of producing speech.
Because only one side of the brain can talk about what it is experiencing,
FIGURE 2 The Split-Brain Operation. A “window” has been people who speak with a person with a split brain are conversing with only one
opened in the side of the brain so that we can see the corpus
hemisphere: the left. The actions of the right hemisphere are more difficult to
callosum being cut at the midline of the brain.
detect. Even the patient’s left hemisphere has to learn about the independent
existence of the right hemisphere. One of the first things that these patients
say they notice after the operation is that their left hand seems to have a “mind of its own.” For
example, patients may find themselves putting down a book held in the left hand, even if they
have been reading it with great interest. This conflict occurs because the right hemisphere, which
controls the left hand, cannot read and therefore finds the book boring. At other times, these
cerebral hemispheres The two
symmetrical halves of the brain; they patients surprise themselves by making obscene gestures (with the left hand) when they do not
constitute the major part of the brain. intend to. A psychologist once reported that a man with a split brain had attempted to beat his
wife with one hand and protect her with the other. Did he
really want to hurt her? Yes and no, I guess.
Left
hand One exception to the crossed representation of sen-
chooses sory information is the olfactory system. That is, when a
a rose
Perfume with person sniffs a flower through the left nostril, only the left
Left nostril aroma of rose
brain receives a sensation of the odor. Thus, if the right
is plugged is presented
to right nostril nostril of a patient with a split brain is closed, leaving
Person only the left nostril open, the patient will be able to tell us
denies Olfactory what the odors are (Gordon and Sperry, 1969). However,
smelling information if the odor enters the right nostril, the patient will say that
anything
he or she smells nothing. But, in fact, the right brain has
Control of
perceived the odor and can identify it. To show this, we
speech
ask the patient to smell an odor with the right nostril and
then reach for some objects that are hidden from view by
Control a partition. If asked to use the left hand, controlled by the
of left
hemisphere that detected the smell, the patient will select
hand
the object that corresponds to the odor—a plastic flower
for a floral odor, a toy fish for a fishy odor, a model tree
for the odor of pine, and so forth. But if asked to use the
right hand, the patient fails the test because the right hand
Left hemisphere Right hemisphere is connected to the left hemisphere, which did not smell
the odor. (See Figure 3.)
The effects of cutting the corpus callosum reinforce
Corpus callosum the conclusion that we become conscious of something
has been cut only if information about it is able to reach the parts of
FIGURE 3 Smelling with a Split Brain. Identification of an object occurs in response the brain responsible for verbal communication, which
to an olfactory stimulus by a person with a split brain. are located in the left hemisphere. If the information does
4
Origins of Behavioral Neuroscience
not reach these parts of the brain, then that information does not reach the consciousness associ-
ated with these mechanisms. We still know very little about the physiology of consciousness, but
studies of people with brain damage are beginning to provide us with some useful insights.
SECTION SUMMARY
Understanding Human Consciousness: A Physiological Approach
The concept of the mind has been with us for a long time—probably from Thought Questions
the earliest history of our species. Modern science has concluded that the 1. Could a sufficiently large and complex computer ever be pro-
world consists of matter and energy and that what we call the mind can be grammed to be aware of itself? Suppose that someone someday
explained by the same laws that govern all other natural phenomena. Studies claims to have done just that. What kind of evidence would you
of the functions of the human nervous system tend to support this position, need to prove or disprove this claim?
as the specific example of the split brain shows. Brain damage, by discon- 2. Is consciousness found in animals other than humans? Is the abil-
necting brain functions from the speech mechanisms in the left hemisphere, ity of some animals to communicate with each other and with
reveals that the mind does not have direct access to all brain functions. humans evidence for at least some form of awareness of self and
When sensory information about a particular object is presented only others?
to the right hemisphere of a person who has had a split-brain operation, 3. Clearly, the left hemisphere of a person with a split brain is conscious
the person is not aware of the object but can, nevertheless, indicate by of the information it receives and of its own thoughts. It is not con-
movements of the left hand that the object has been perceived. This phe- scious of the mental processes of the right hemisphere. But is it pos-
nomenon suggests that consciousness involves operations of the verbal sible that the right hemisphere is conscious too, but is just unable to
mechanisms of the left hemisphere. Indeed, consciousness may be, in talk to us? How could we possibly find out whether it is? Do you see
large part, a matter of us “talking to ourselves.” Thus, once we understand some similarities between this issue and the one raised in the first
the language functions of the brain, we may have gone a long way to question?
understanding how the brain can be conscious of its own existence.
The Nature of Behavioral Neuroscience
The modern history of behavioral neuroscience has been written by psychologists who have com-
bined the experimental methods of psychology with those of physiology and have applied them to
the issues that concern all psychologists. Thus, we have studied perceptual processes, control of
movement, sleep and waking, reproductive behaviors, ingestive behaviors, emotional behaviors,
learning, and language. In recent years we have also begun to study the physiology of pathological
conditions, such as addictions and mental disorders.
The Goals of Research
The goal of all scientists is to explain the phenomena they study. But what do we mean by ex-
plain? Scientific explanation takes two forms: generalization and reduction. Most psychologists
deal with generalization. They explain particular instances of behavior as examples of general
laws, which they deduce from their experiments. For instance, most psychologists would explain
a pathologically strong fear of dogs as an example of a particular form of learning called classi-
cal conditioning. Presumably, the person was frightened earlier in life by a dog. An unpleasant
stimulus was paired with the sight of the animal (perhaps the person was knocked down by an
exuberant dog or was attacked by a vicious one), and the subsequent sight of dogs evokes the
earlier response: fear. generalization Type of scientific
Most physiologists deal with reduction. They explain complex phenomena in terms of sim- explanation; a general conclusion
based on many observations of similar
pler ones. For example, they may explain the movement of a muscle in terms of the changes in
phenomena.
the membranes of muscle cells, the entry of particular chemicals, and the interactions among
reduction Type of scientific explanation;
protein molecules within these cells. By contrast, a molecular biologist would explain these events
a phenomenon is described in terms
in terms of forces that bind various molecules together and cause various parts of the molecules of the more elementary processes that
to be attracted to one another. In turn, the job of an atomic physicist is to describe matter and underlie it.
5