NEUROSCIENCE: Third Edition
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Library of Congress Cataloging-in-Publication Data
Neuroscience / edited by Dale Purves ... [et al.].— 3rd ed.
p. ; cm.
Includes bibliographical references and index.
ISBN 0-87893-725-0 (casebound : alk. paper)
1. Neurosciences.
[DNLM: 1. Nervous System Physiology. 2. Neurochemistry.
WL 102 N50588 2004] I. Purves, Dale.
QP355.2.N487 2004
612.8—dc22 2004003973
Contributors
George J. Augustine, Ph.D.
Dona M. Chikaraishi, Ph.D.
Michael D. Ehlers, M.D., Ph.D.
Gillian Einstein, Ph.D.
David Fitzpatrick, Ph.D.
William C. Hall, Ph.D.
Erich Jarvis, Ph.D.
Lawrence C. Katz, Ph.D.
Julie Kauer, Ph.D.
Anthony-Samuel LaMantia, Ph.D.
James O. McNamara, M.D.
Richard D. Mooney, Ph.D.
Miguel A. L. Nicolelis, M.D., Ph.D.
Dale Purves, M.D.
Peter H. Reinhart, Ph.D.
Sidney A. Simon, Ph.D.
J. H. Pate Skene, Ph.D.
James Voyvodic, Ph.D.
Leonard E. White, Ph.D.
S. Mark Williams, Ph.D.
UNIT EDITORS
UNIT I: George J. Augustine
UNIT II: David Fitzpatrick
UNIT III: William C. Hall
UNIT IV: Anthony-Samuel LaMantia
UNIT V: Dale Purves
Contents in Brief
1. Studying the Nervous Systems of Humans and Other Animals 1
UNIT I NEURAL SIGNALING
2. Electrical Signals of Nerve Cells 31
3. Voltage-Dependent Membrane Permeability 47
4. Channels and Transporters 69
5. Synaptic Transmission 93
6. Neurotransmitters, Receptors, and Their Effects 129
7. Molecular Signaling within Neurons 165
UNIT II SENSATION AND SENSORY PROCESSING
8. The Somatic Sensory System 189
9. Pain 209
10. Vision: The Eye 229
11. Central Visual Pathways 259
12. The Auditory System 283
13. The Vestibular System 315
14. The Chemical Senses 337
UNIT III MOVEMENT AND ITS CENTRAL CONTROL
15. Lower Motor Neuron Circuits and Motor Control 371
16. Upper Motor Neuron Control of the Brainstem and Spinal Cord 393
17. Modulation of Movement by the Basal Ganglia 417
18. Modulation of Movement by the Cerebellum 435
19. Eye Movements and Sensory Motor Integration 453
20. The Visceral Motor System 469
UNIT IV THE CHANGING BRAIN
21. Early Brain Development 501
22. Construction of Neural Circuits 521
23. Modification of Brain Circuits as a Result of Experience 557
24. Plasticity of Mature Synapses and Circuits 575
UNIT V COMPLEX BRAIN FUNCTIONS
25. The Association Cortices 613
26. Language and Speech 637
27. Sleep and Wakefulness 659
28. Emotions 687
29. Sex, Sexuality, and the Brain 711
30. Memory 733
APPENDIX A THE BRAINSTEM AND CRANIAL NERVES 755
APPENDIX B VASCULAR SUPPLY, THE MENINGES, AND THE VENTRICULAR SYSTEM 763
Contents
Chapter 1 Studying the Nervous Systems
of Humans and Other Animals 1
Overview 1
Genetics, Genomics, and the Brain 1
The Cellular Components of the Nervous System 2
Neurons 4
Neuroglial Cells 8
Cellular Diversity in the Nervous System 9
Neural Circuits 11
Overall Organization of the Human Nervous
System 14
Neuroanatomical Terminology 16
The Subdivisions of the Central Nervous System 18
Organizational Principles of Neural Systems 20
Functional Analysis of Neural Systems 23
Analyzing Complex Behavior 24
BOX A Brain Imaging Techniques 25
Summary 26
Unit I NEURAL SIGNALING
Chapter 2 Electrical Signals
of Nerve Cells 31
Overview 31
Electrical Potentials across Nerve Cell Membranes 31
How Ionic Movements Produce Electrical Signals 34
The Forces That Create Membrane Potentials 36
Electrochemical Equilibrium in an Environment with
More Than One Permeant Ion 38
The Ionic Basis of the Resting Membrane Potential 40
BOX A The Remarkable Giant Nerve Cells
of Squid 41
The Ionic Basis of Action Potentials 43
BOX B Action Potential Form
and Nomenclature 44
Summary 45
Chapter 3 Voltage-Dependent Membrane
Permeability 47
Overview 47
Ionic Currents Across Nerve Cell Membranes 47
BOX A The Voltage Clamp Method 48
Two Types of Voltage-Dependent Ionic Current 49
Two Voltage-Dependent Membrane Conductances 52
Reconstruction of the Action Potential 54
Long-Distance Signaling by Means of Action
Potentials 56
BOX B Threshold 57
BOX C Passive Membrane Properties 60
The Refractory Period 61
Increased Conduction Velocity as a Result
of Myelination 63
Summary 65
BOX D Multiple Sclerosis 66
Chapter 4 Channels and Transporters 69
Overview 69
Ion Channels Underlying Action Potentials 69
BOX A The Patch Clamp Method 70
The Diversity of Ion Channels 73
BOX B Expression of Ion Channels in Xenopus
Oocytes 75
Voltage-Gated Ion Channels 76
Ligand-Gated Ion Channels 78
Stretch- and Heat-Activated Channels 78
The Molecular Structure of Ion Channels 79
BOX C Toxins That Poison Ion Channels 82
BOX D Diseases Caused by Altered Ion
Channels 84
Active Transporters Create and Maintain Ion
Gradients 86
Functional Properties of the Na+/K+ Pump 87
The Molecular Structure of the Na+/K+ Pump 89
Summary 90
Chapter 5 Synaptic Transmission 93
Overview 93
Electrical Synapses 93
Signal Transmission at Chemical Synapses 96
Properties of Neurotransmitters 96
BOX A Criteria That Define a
Neurotransmitter 99
Quantal Release of Neurotransmitters 102
Release of Transmitters from Synaptic Vesicles 103
Local Recycling of Synaptic Vesicles 105
The Role of Calcium in Transmitter Secretion 107
BOX B Diseases That Affect the Presynaptic
Terminal 108
Unit II SENSATION AND SENSORY PROCESSING
Chapter 8 The Somatic Sensory System 189
Overview 189
Cutaneous and Subcutaneous Somatic Sensory
Receptors 189
Mechanoreceptors Specialized to Receive Tactile
Information 192
Differences in Mechanosensory Discrimination across
the Body Surface 193
BOX A Receptive Fields and Sensory Maps
in the Cricket 195
BOX B Dynamic Aspects of Somatic Sensory
Receptive Fields 196
Mechanoreceptors Specialized for Proprioception 197
Active Tactile Exploration 199
The Major Afferent Pathway for Mechanosensory
Information: The Dorsal Column–Medial Lemniscus
System 199
The Trigeminal Portion of the Mechanosensory
System 202
BOX C Dermatomes 202
The Somatic Sensory Components of the Thalamus 203
The Somatic Sensory Cortex 203
Higher-Order Cortical Representations 206
BOX D Patterns of Organization within the
Sensory Cortices: Brain Modules 207
Summary 208
Chapter 9 Pain 209
Overview 209
Nociceptors 209
Transduction of Nociceptive Signals 211
BOX A Capsaicin 212
Central Pain Pathways 213
BOX B Referred Pain 215
BOX C A Dorsal Column Pathway for Visceral
Pain 218
Sensitization 220
BOX D Phantom Limbs and Phantom Pain 222
Descending Control of Pain Perception 224
The Placebo Effect 224
The Physiological Basis of Pain Modulation 225
Summary 227
Chapter 10 Vision:The Eye 229
Overview 229
Anatomy of the Eye 229
The Formation of Images on the Retina 231
BOX A Myopia and Other Refractive Errors 232
The Retina 234
Phototransduction 236
BOX B Retinitis Pigmentosa 239
Functional Specialization of the Rod and Cone
Systems 240
BOX C Macular Degeneration 243
Anatomical Distribution of Rods and Cones 244
Cones and Color Vision 245
BOX D The Importance of Context in Color
Perception 247
Retinal Circuits for Detecting Luminance
Change 249
BOX E The Perception of Light Intensity 250
Contribution of Retinal Circuits to Light
Adaptation 254
Summary 257
Chapter 11 Central Visual Pathways 259
Overview 259
Central Projections of Retinal Ganglion Cells 259
BOX A The Blind Spot 262
The Retinotopic Representation of the Visual Field 263
Visual Field Deficits 267
The Functional Organization of the Striate Cortex 269
The Columnar Organization of the Striate Cortex 271
BOX B Random Dot Stereograms and Related
Amusements 272
Division of Labor within the Primary Visual
Pathway 275
BOX C Optical Imaging of Functional Domains in
the Visual Cortex 276
The Functional Organization of Extrastriate Visual
Areas 278
Summary 281
Chapter 12 The Auditory System 283
Overview 283
Sound 283
The Audible Spectrum 284
A Synopsis of Auditory Function 285
BOX A Four Causes of Acquired Hearing Loss 285
BOX B Music 286
The External Ear 287
The Middle Ear 289
The Inner Ear 289
BOX C Sensorineural Hearing Loss and Cochlear
Implants 290
BOX D The Sweet Sound of Distortion 295
Hair Cells and the Mechanoelectrical Transduction of
Sound Waves 294
Two Kinds of Hair Cells in the Cochlea 300
Tuning and Timing in the Auditory Nerve 301
How Information from the Cochlea Reaches Targets in
the Brainstem 303
Integrating Information from the Two Ears 303
Monaural Pathways from the Cochlear Nucleus to the
Lateral Lemniscus 307
Integration in the Inferior Colliculus 307
The Auditory Thalamus 308
The Auditory Cortex 309
BOX E Representing Complex Sounds in the
Brains of Bats and Humans 310
Summary 313
Chapter 13 The Vestibular System 315
Overview 315
The Vestibular Labyrinth 315
Vestibular Hair Cells 316
The Otolith Organs: The Utricle and Saccule 317
BOX A A Primer on Vestibular Navigation 318
BOX B Adaptation and Tuning of Vestibular Hair
Cells 320
How Otolith Neurons Sense Linear Forces 322
The Semicircular Canals 324
How Semicircular Canal Neurons Sense Angular
Accelerations 325
BOX C Throwing Cold Water on the Vestibular
System 326
Central Pathways for Stabilizing Gaze, Head, and
Posture 328
Vestibular Pathways to the Thalamus and Cortex 331
BOX D Mauthner Cells in Fish 332
Summary 333
Chapter 14 The Chemical Senses 337
Overview 337
The Organization of the Olfactory System 337
Olfactory Perception in Humans 339
Physiological and Behavioral Responses to
Odorants 341
The Olfactory Epithelium and Olfactory Receptor
Neurons 342
BOX A Olfaction, Pheromones, and Behavior in
the Hawk Moth 344
The Transduction of Olfactory Signals 345
Odorant Receptors 346
Olfactory Coding 348
The Olfactory Bulb 350
BOX B Temporal “Coding”of Olfactory
Information in Insects 350
Central Projections of the Olfactory Bulb 353
The Organization of the Taste System 354
Taste Perception in Humans 356
Idiosyncratic Responses to Tastants 357
The Organization of the Peripheral Taste System 359
Taste Receptors and the Transduction of Taste
Signals 360
Neural Coding in the Taste System 362
Trigeminal Chemoreception 363
Summary 366
Unit III MOVEMENT AND ITS CENTRAL CONTROL
Chapter 15 Lower Motor Neuron Circuits
and Motor Control 371
Overview 371
Neural Centers Responsible for Movement 371
Motor Neuron–Muscle Relationships 373
The Motor Unit 375
The Regulation of Muscle Force 377
The Spinal Cord Circuitry Underlying Muscle Stretch
Reflexes 379
The Influence of Sensory Activity on Motor Behavior
381
Other Sensory Feedback That Affects Motor
Performance 382
BOX A Locomotion in the Leech and the Lamprey
384
Flexion Reflex Pathways 387
Spinal Cord Circuitry and Locomotion 387
BOX B The Autonomy of Central Pattern
Generators: Evidence from the Lobster
Stomatogastric Ganglion 388
The Lower Motor Neuron Syndrome 389
BOX C Amyotrophic Lateral Sclerosis 391
Summary 391
Chapter 16 Upper Motor Neuron Control
of the Brainstem and Spinal
Cord 393
Overview 393
Descending Control of Spinal Cord Circuitry:
General Information 393
Motor Control Centers in the Brainstem: Upper Motor
Neurons That Maintain Balance and Posture 397
BOX A The Reticular Formation 398
The Corticospinal and Corticobulbar Pathways:
Upper Motor Neurons That Initiate Complex
Voluntary Movements 402
BOX B Descending Projections to Cranial Nerve
Motor Nuclei and Their Importance
in Diagnosing the Cause of Motor
Deficits 404
Functional Organization of the Primary Motor Cortex
405
BOX C What Do Motor Maps Represent? 408
The Premotor Cortex 411
BOX D Sensory Motor Talents and Cortical
Space 410
Damage to Descending Motor Pathways: The Upper
Motor Neuron Syndrome 412
BOX E Muscle Tone 414
Summary 415
Chapter 17 Modulation of Movement by
the Basal Ganglia 417
Overview 417
Projections to the Basal Ganglia 417
Projections from the Basal Ganglia to Other Brain
Regions 422
Evidence from Studies of Eye Movements 423
Circuits within the Basal Ganglia System 424
BOX A Huntington’s Disease 426
BOX B Parkinson’s Disease: An Opportunity for
Novel Therapeutic Approaches 429
BOX C Basal Ganglia Loops and Non-Motor
Brain Functions 432
Summary 433
Chapter 18 Modulation of Movement by
the Cerebellum 435
Overview 435
Organization of the Cerebellum 435
Projections to the Cerebellum 438
Projections from the Cerebellum 440
Circuits within the Cerebellum 441
BOX A Prion Diseases 444
Cerebellar Circuitry and the Coordination of Ongoing
Movement 445
Futher Consequences of Cerebellar Lesions 448
Summary 449
BOX B Genetic Analysis of Cerebellar Function 450
Chapter 19 Eye Movements and Sensory
Motor Integration 453
Overview 453
What Eye Movements Accomplish 453
The Actions and Innervation of Extraocular Muscles
454
BOX A The Perception of Stabilized Retinal
Images 456
Types of Eye Movements and Their Functions 457
Neural Control of Saccadic Eye Movements 458
BOX B Sensory Motor Integration in the
Superior Colliculus 462
Neural Control of Smooth Pursuit Movements 466
Neural Control of Vergence Movements 466
Summary 467
Chapter 20 The Visceral Motor System 469
Overview 469
Early Studies of the Visceral Motor System 469
Distinctive Features of the Visceral Motor System 470
The Sympathetic Division of the Visceral Motor
System 471
The Parasympathetic Division of the Visceral Motor
System 476
The Enteric Nervous System 479
Sensory Components of the Visceral Motor System 480
Central Control of Visceral Motor Functions 483
BOX A The Hypothalamus 484
Neurotransmission in the Visceral Motor System 487
BOX B Horner’s Syndrome 488
BOX C Obesity and the Brain 490
Visceral Motor Reflex Functions 491
Autonomic Regulation of Cardiovascular Function 491
Autonomic Regulation of the Bladder 493
Autonomic Regulation of Sexual Function 496
Summary 498
Unit IV THE CHANGING BRAIN
Chapter 21 Early Brain Development 501
Overview 501
The Initial Formation of the Nervous System:
Gastrulation and Neurulation 501
The Molecular Basis of Neural Induction 503
BOX A Stem Cells: Promise and Perils 504
BOX B Retinoic Acid:Teratogen and Inductive
Signal 506
Formation of the Major Brain Subdivisions 510
BOX C Homeotic Genes and Human Brain
Development 513
BOX D Rhombomeres 514
Genetic Abnormalities and Altered Human Brain
Development 515
The Initial Differentiation of Neurons and Glia 516
BOX E Neurogenesis and Neuronal Birthdating
517
The Generation of Neuronal Diversity 518
Neuronal Migration 520
BOX F Mixing It Up: Long-Distance Neuronal
Migration 524
Summary 525
Chapter 22 Construction of Neural
Circuits 527
Overview 527
The Axonal Growth Cone 527
Non-Diffusible Signals for Axon Guidance 528
BOX A Choosing Sides: Axon Guidance at the
Optic Chiasm 530
Diffusible Signals for Axon Guidance:
Chemoattraction and Repulsion 534
The Formation of Topographic Maps 537
Selective Synapse Formation 539
BOX B Molecular Signals That Promote Synapse
Formation 542
Trophic Interactions and the Ultimate Size of Neuronal
Populations 543
Further Competitive Interactions in the Formation of
Neuronal Connections 545
Molecular Basis of Trophic Interactions 547
BOX C Why Do Neurons Have Dendrites? 548
BOX D The Discovery of BDNF and the
Neurotrophin Family 552
Neurotrophin Signaling 553
Summary 554
Chapter 23 Modification of Brain Circuits
as a Result of Experience 557
Overview 557
Critical Periods 557
BOX A Built-In Behaviors 558
The Development of Language:
Example of a Human Critical Period 559
BOX B Birdsong 560
Critical Periods in Visual System Development 562
Effects of Visual Deprivation on Ocular Dominance 563
BOX C Transneuronal Labeling with Radioactive
Amino Acids 564
Visual Deprivation and Amblyopia in Humans 568
Mechanisms by which Neuronal Activity Affects the
Development of Neural Circuits 569
Cellular and Molecular Correlates of Activity-
Dependent Plasticity during Critical Periods 572
Evidence for Critical Periods in Other Sensory
Systems 572
Summary 573
Chapter 24 Plasticity of Mature Synapses
and Circuits 575
Overview 575
Synaptic Plasticity Underlies Behavioral Modification
in Invertebrates 575
BOX A Genetics of Learning and Memory in the
Fruit Fly 581
Short-Term Synaptic Plasticity in the Mammalian
Nervous System 582
Long-Term Synaptic Plasticity in the Mammalian
Nervous System 583
Long-Term Potentiation of Hippocampal Synapses 584
Molecular Mechanisms Underlying LTP 587
BOX B Dendritic Spines 590
Long-Term Synaptic Depression 592
BOX C Silent Synapses 594
Changes in Gene Expression Cause Enduring
Changes in Synaptic Function during LTP and
LTD 597
Plasticity in the Adult Cerebral Cortex 599
BOX D Epilepsy:The Effect of Pathological
Activity on Neural Circuitry 600
Recovery from Neural Injury 602
Generation of Neurons in the Adult Brain 605
BOX E Why Aren’t We More Like Fish and
Frogs? 606
Summary 609
Unit V COMPLEX BRAIN FUNCTIONS
Chapter 25 The Association Cortices 613
Overview 613
The Association Cortices 613
An Overview of Cortical Structure 614
Specific Features of the Association Cortices 615
BOX A A More Detailed Look at Cortical
Lamination 617
Lesions of the Parietal Association Cortex: Deficits of
Attention 619
Lesions of the Temporal Association Cortex:
Deficits of Recognition 622
Lesions of the Frontal Association Cortex: Deficits of
Planning 623
BOX B Psychosurgery 625
“Attention Neurons” in the Monkey Parietal Cortex 626
“Recognition Neurons” in the Monkey Temporal
Cortex 627
“Planning Neurons” in the Monkey Frontal Cortex 630
BOX C Neuropsychological Testing 632
BOX D Brain Size and Intelligence 634
Summary 635
Chapter 26 Language and Speech 637
Overview 637
Language Is Both Localized and Lateralized 637
Aphasias 638
BOX A Speech 640
BOX B Do Other Animals Have Language? 642
BOX C Words and Meaning 645
ADramatic Confirmation of Language Lateralization
646
Anatomical Differences between the Right and Left
Hemispheres 648
Mapping Language Functions 649
BOX D Language and Handedness 650
The Role of the Right Hemisphere in Language 654
Sign Language 655
Summary 656
Chapter 27 Sleep and Wakefulness 659
Overview 659
Why Do Humans (and Many Other Animals) Sleep?
659
BOX A Styles of Sleep in Different Species 661
The Circadian Cycle of Sleep and Wakefulness 662
Stages of Sleep 665
BOX B Molecular Mechanisms of Biological
Clocks 666
BOX C Electroencephalography 668
Physiological Changes in Sleep States 671
The Possible Functions of REM Sleep and Dreaming
671
Neural Circuits Governing Sleep 674
BOX D Consciousness 675
Thalamocortical Interactions 679
Sleep Disorders 681
BOX E Drugs and Sleep 682
Summary 684
Chapter 28 Emotions 687
Overview 687
Physiological Changes Associated with Emotion 687
The Integration of Emotional Behavior 688
BOX A Facial Expressions: Pyramidal and
Extrapyramidal Contributions 690
The Limbic System 693
BOX B The Anatomy of the Amygdala 696
The Importance of the Amygdala 697
BOX C The Reasoning Behind an Important
Discovery 698
The Relationship between Neocortex and Amygdala
701
BOX D Fear and the Human Amygdala:
A Case Study 702
BOX E Affective Disorders 704
Cortical Lateralization of Emotional Functions 705
Emotion, Reason, and Social Behavior 707
Summary 708
Chapter 29 Sex, Sexuality, and the Brain 711
Overview 711
Sexually Dimorphic Behavior 711
What Is Sex? 712
BOX A The Development of Male and Female
Phenotypes 714
Hormonal Influences on Sexual Dimorphism 715
BOX B The Case of Bruce/Brenda 716
The Effect of Sex Hormones on Neural Circuitry 718
BOX C The Actions of Sex Hormones 718
Other Central Nervous System Dimorphisms
Specifically Related to Reproductive Behaviors 720
Brain Dimorphisms Related to Cognitive Function 728
Hormone-Sensitive Brain Circuits in Adult Animals 729
Summary 731
Chapter 30 Memory 733
Overview 733
Qualitative Categories of Human Memory 733
Temporal Categories of Memory 734
BOX A Phylogenetic Memory 735
The Importance of Association in Information Storage
736
Forgetting 738
BOX B Savant Syndrome 739
Brain Systems Underlying Declarative Memory
Formation 741
BOX C Clinical Cases That Reveal the Anatomical
Substrate for Declarative Memories 742
Brain Systems Underlying Long-Term Storage of
Declarative Memory 746
Brain Systems Underlying Nondeclarative Learning
and Memory 748
Memory and Aging 749
BOX D Alzheimer’s Disease 750
Summary 753
Appendix A The Brainstem and Cranial
Nerves 755
Appendix B Vascular Supply, the Meninges,
and the Ventricular System 763
The Blood Supply of the Brain and Spinal Cord 763
The Blood-Brain Barrier 766
BOX A Stroke 767
The Meninges 768
The Ventricular System 770
Glossary
Illustration Source References
Index
Molecular Mechanisms of Transmitter Secretion 110
Neurotransmitter Receptors 113
BOX C Toxins That Affect Transmitter
Release 115
Postsynaptic Membrane Permeability Changes during
Synaptic Transmission 116
Excitatory and Inhibitory Postsynaptic Potentials 121
Summation of Synaptic Potentials 123
Two Families of Postsynaptic Receptors 124
Summary 126
Chapter 6 Neurotransmitters and Their
Receptors 129
Overview 129
Categories of Neurotransmitters 129
Acetylcholine 129
BOX A Addiction 134
BOX B Neurotoxins that Act on Postsynaptic
Receptors 136
Glutamate 137
BOX C Myasthenia Gravis: An Autoimmune
Disease of Neuromuscular Synapses 140
GABA and Glycine 143
BOX D Excitotoxicity Following Acute Brain
Injury 145
The Biogenic Amines 147
BOX E Biogenic Amine Neurotransmitters and
Psychiatric Disorders 148
ATP and Other Purines 152
Peptide Neurotransmitters 153
Unconventional Neurotransmitters 157
BOX F Marijuana and the Brain 160
Summary 161
Chapter 7 Molecular Signaling within
Neurons 165
Overview 165
Strategies of Molecular Signaling 165
The Activation of Signaling Pathways 167
Receptor Types 168
G-Proteins and Their Molecular Targets 170
Second Messengers 172
Second Messenger Targets: Protein Kinases and
Phosphatases 175
Nuclear Signaling 178
Examples of Neuronal Signal Transduction 181
Summary 184
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